Perception and Neuroscience

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  • Created by: megs543
  • Created on: 26-02-19 16:19
PSYCHOPHARMACOLOGY OF REWARD
PSYCHOPHARMACOLOGY OF REWARD
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What does the synapse consist of?
Dendrites, cell body, axon termials, axons.
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What is synaptic transmission?
Important means of cells communicating with each other in the nervous sytstem. One neuron releases neurotransmitter molecules onto another. The neurotransmitter molecules bind to and activate receptors on the target cell.
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The activated receptor then activate target molecules in the cell. Other receptors act as ion channels that tranduce the chemical signals into an electrical signal.
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Paracrine signalling? (other form of chemical communication)
In paracrine signalling a cell releases paracrine molecules that activate nearby target cells with appropriate receptors. Paracrine signallin acts at a longer distance than sypnatic transmission.
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Endocrine signalling? (other form of chemical comunication)
Refers to the secretion of hormones into the blood stream (capiliary). The hormones reach tissues throughout the body. Those cells with appropriate receptors become activated.
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What components does chemical signalling require?
A mollecular signal that transmits information from one cell to another, A receptor molecule that tranduces information provided by the sigal. A target molecule that mediates the cellular response.
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What is intracellular signal transduction?
The part of the chemical signalling that takes place in the cell.
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Signal transuction- where the cell is amplified?
The receptor protein combined to the neurotransmitter (norepinephrine). The activation of a receptor by norephinephrine can lead to the activation of multiple G-proteins inside cells. This is the 1st amplification step.
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These activated proteins combine to other signalling molecules, such as the enzyme Adenylyl cyclase. This way asenylyl cyclase becomes activated. Each activated enzyme creates a large number of cAMP and ATP molecules.
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cAMP production (Cyclic adenosine monophosphate) is the 2nd amplification step. cAMP binds to and activates another family of enzymes; protein kinase. They phospholylate many target proteins. This is the 3rd amplification step.
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What does this produce overall?
Although, not all steps involves amplification. The cascade results in a tremendous increase in the potency of the initial signal.
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Give examples of small molecule neurotransmitters?
Acetylcholine (excitatory)  aminobutyric acid (GABA) (inhibitory) Glycine (inhibitory) Glutamate (excitatory) Aspartate (excitatory), Dopamine (excitatory) Noradrenaline (excitatory) Serotonin (excitatory) Histamine (excitatory).
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Give examples of neuropeptide neurotransmitters?
Corticotropin releasing hormone Corticotropin (ACTH) Beta-endorphin Substance P Neurotensin Somatostatin, Bradykinin Vasopressin Angiotensin II.
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What is substance p?
linked to affective disorders incl pain-related, thought to be associated with chronic inflammation- increasingly linking to mental health conditions like depression.
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What is beta endorphin?
opiod peptide not unlike enkephalin which will be discussed later- painkillers, recreational drugs like heroin.
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What is norephinephrine?
action, closely related to the body, preparing the body for action, effects on the periphery.
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What is serotonin?
anti-depressants (e.g. Prozac), strongly related to mood and mental disorders, projected widely in the brain, the raphe nuclei is the source of serotonin.
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What is dopamine?
action and attention.
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What is acetylcholine?
finds it source in the pontine nuclei, widely projected along the brain.
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First stage of brain reward circuitry?
Anterior Bed Nucleus of the Medial Forebrain Bundle -> Ventral Tegmental Area .These projections use a variety of different neurotransmitters. Focus on reward circuitry, complex area with large variety of neurotransmitters.
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Animal research involving rewards?
has identified a brain reward circuitry that we summarise here. Reward neurons are particularly present in subcortical areas of the brain depicted here (animal brain).
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Where do they originate?
First stage reward neurons originate in the anterior bed nucleus of the medial forebrain bundle and project to the ventral tegmental area. These projections use a variety of different neurotransmitters.
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Second stage of brain reward circuitry?
Second stage reward neurons project from the ventral tegmental area to the nucleus accumbens. This is often considered the critical step in the reward pathway and these projections use dopamine as their primary neurotransmitter.
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Third stage of brain reward circuitry?
Finally third stage neurons project from the nucleus accumbens back to the ventral pallidum and the anterior bed nucleus of the MFB. One very important neurotransmitter used here is enkephalin, an endogenous opioid neurotransmitter.
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First stage origination?
First stage reward neurons originate in the anterior bed nucleus of the medial forebrain bundle and project to the ventral tegmental area. These projections use a variety of different neurotransmitters.
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Second stage?
Second stage reward neurons project from the ventral tegmental area to the nucleus accumbens. This is often considered the critical step in the reward pathway and these projections use dopamine as their primary neurotransmitter.
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Third stage?
Finally third stage neurons project from the nucleus accumbens back to the ventral pallidum and the anterior bed nucleus of the MFB. One very important neurotransmitter used here is enkephalin, an endogenous opioid neurotransmitter.
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Dopamine and wanting?
Brain DA systems Activated by ‘wanted’ incentive stimuli Role in acquisition & direction of reward Activity in DA systems increased by Presence of natural rewards Stimuli that predict reward availability Appetitive aspects of reward.
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Activation of the 2nd stage dopaminergic fibres? Old views?
Until relatively recently, the activation of the 2nd-stage dopaminergic fibres, and the subsequent release of dopamine within the nucleus accumbens, were considered to directly mediate reward, or the experience of pleasure.
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Example?
For example, many drugs of abuse cause dopamine release within the nucleus accumbens, as does food in a hungry animal.
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Recent view as other view untenable?
Instead, we now consider that dopamine fibres are activated by wanted incentive stimuli and have an essential role in the acquisition and direction of natural reward- and drug-seeking behavior.  
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What do electrophysiological and microdialysis studies show?
DA system activity is increased by the presence of natural rewards (food, water, sexual mates, etc), or stimuli that predict their availability (or are associated with the rewards through conditioning) – rather than by consummatory behaviour (eating)
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Wanting (and not liking) study?
Pecina et al (2003) used a genetic approach where a mutation in the dopamine transporter (DAT) meant that levels of DAT were significantly reduced and leads to mutant mice having 70% elevated levels of synaptic dopamine.
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What did they examine?
They examined the consequences of the elevated synaptic dopamine on (1) spontaneous food intake, (2) incentive motivation and learning to obtain a palatable sweet reward in a runway task, and (3) affective “liking” reactions elicited sucrose taste.
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What were the results?
Food intake of DAT knockdown mutant mice was slightly higher than that of wild-type mice over a 4 week period. Mutant mice ate 21% more chow pellets/d on average than wild-type mice.
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As might be expected from their higher food consumption, DAT knockdown mutant mice had slightly but consistently heavier body weights.
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All mice gained 5% body weight over a 1 month period at similar rates of ascent and mutants were always 6% heavier than wild-type mice at every week throughout the month.
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Runaway paradigm?
Runway learning and performance for a food reward is a traditional behavioral paradigm, which generates acquisition learning curves, as well as running speed and approach trajectory measures of incentive motivation and performance if the task is lear
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Example?
measures of wanting. The runway apparatus consisted of three compartments: a start box, a central runway and a goal box.
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What was the task?
put sweet breakfast cereal (Froot Loops!) in box as reward, measure running speed, number of times rats will run. Link to ‘wanting’.
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Session 1-3?
Sessions 1-3 were habituation sessions to the apparatus. Animals were placed in the goal box and allowed to eat the treat.
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Session 4-6?
Sessions 4-6 were training sessions to running. Start box placed increasingly further away from goal box over 3 sessions.
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Session 7-11?
Sessions 7-11 had reward in goal box (Fruit loop).
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Results?
DAT knockdown mutant mice showed enhanced acquisition and incentive performance for a sweet reward in the runway task. The enhancement was especially evident during the incentive training phase when mice were learning the task.
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Initially?
mice from both strains reached the goal slowly before learning, during goal box pre-exposure sessions. DAT knockdowns reached the reward more quickly than wild types each day during the training phase (sessions 8–11).
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DAT knockdown mice did not appear to “like” the taste of sucrose more than wild-type mice in the taste reactivity test, despite their higher incentive motivation or “wanting” for a sweet reward and higher food intake.
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Hyperdopaminergic mutant mice?
displayed no more positive hedonic reactions to sucrose at low and medium concentrations, and mutants actually displayed fewer liking reactions at the highest sucrose concentration.
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The final stage of reward pathway?
running from the nucleus accumbens to the ventral pallidum typically uses the neurotransmitter enkephalin, which is an endogenous or naturally-produced opioid.
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Endogeous opiod release role?
consummatory aspects of reward. It has been proven that there is a significant role for opioids to enhance liking reactions: opioid agonists suppress aversive reactions to bitter tastes and potentiate hedonic reactions to sweet taste.
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Evidence beyond taste reactivity?
strongly supports a crucial role for endogenous opioid systems in food reward, in particular evidence is consistent in supporting a role in liking rather than wanting.
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Example?
For example, opioid receptor blockers (such as naloxone) reduce food intake by shortening meals, and subjects report that previously palatable foods taste less pleasant.
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What is the first study to show morphine is linked to increased liking?
Rideout & Parker (1996)- The ability of morphine to modify sucrose palatability was assessed by the taste reactivity test.
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Experiment 1?
rats were injected with morphine (0.0, 0.5, 2.0, and 10.0 mg/kg, subcutaneously), 30 min before receiving a 10-min intraoral infusion of 2% or 20% sucrose solution.
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What does this figure represent?
presents the mean duration of ingestive reactions elicited by 2% and 20% sucrose solution during each of two 5-min blocks of testing.
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What did the analysis reveal?
significant main effect of concentration with rats spending more time displaying ingestive reactions during an infusion of 20% sucrose than 2% sucrose solution, suggesting that the 20% sucrose is more palatable than 2% sucrose.
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significant main effect of morphine dose with rats administered 2.0 mg/kg spent significantly more time displaying ingestive reactions than did rats in each of the other pretreatment groups.
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Tallett & colleagues study (action of naxolene- an opioid receptor antagonists) in feeding)
In expt 1 they investigated the effects of increasing doses of naloxone on 1-hour free-feeding with a palatable food.
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Results?
Results confirmed that, at doses ≥1.0 mg/kg, naloxone consistently suppresses food consumption and feeding behaviour with reductions of 54%, 61% and 65%, respectively being seen for 1.0, 2.5 and 5.0 mg/kg doses.
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There were no significant differences in the degree of suppression between the lowest and highest doses tested.
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Did anoretic doses of naloxene alter time?
Crucially, the anorectic doses of naloxone did not alter the time taken to find food or to commence feeding, the time spent feeding in the initial phase of testing, or the rate at which food was consumed.
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However?
naloxone did not significantly influence other feeding-related parameters: as latency to locate food source, latency to feed, average length of feeding bouts, and feeding rate were unaffected by naloxone treatment.
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Frequency and naxolene?
Naloxone had no effect on frequency of other behaviours.
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What are neuromodulators?
Substances that do not act like typical neurotransmitters, may affect the action of a neurotransmitter by increasing, decreasing or prolonging its effectiveness, they can diffuse away and influence distant cells. "volume transmission".
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No defining line between neurotransmitters and neuromodulators, the same chemical can act as a neurotransmitter or neuromodulator, schematic of an axon synapsing on dendrite.
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Introduction to dopamine?
Dopamine is also classed as a monoamine neurotransmitter and is concentrated in very specific groups of neurons collectively called the basal ganglia.
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Dopaminergic neurons?
Dopaminergic neurons are widely distributed throughout the brain in three important dopamine systems (pathways): the nigrostriatal, mesocorticolimbic, and the tuberohypophyseal pathways.
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Decrease brain dopamine concentration?
A decreased brain dopamine concentration is a contributing factor in Parkinson’s disease, while an increase in dopamine concentration has a role in the development of schizophrenia.
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What is reinforcement learning?
Classic of pavlovian conditioning (Pavlov), operant or instrumental conditioning (skinner), Rescrla-Wagner's reinforcement learning model- adaption of classical with a maths model, adds elemet of suprise and prediction, predition errors.
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Dopamine and learning?
It has previously been shown that cues predicting a variety of reinforcers including food/water, cocaine or intracranial self-stimulation (ICSS) elicit transient fluctuations in dopamine levels in the shell of the nucleus accumbens (NAc).
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Dopamine and reward?
These dopamine levels have been found to correlate with reward-related learning and are believed to promote reward-seeking behavior. DA therefore acts as a learning signal for reward prediction.
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Olds (1973)?
Olds and Milner observed that a rat with an electrode implanted into particular areas of the brain would repeatedly return to the place in the cage where the electrical stimulation had been applied- as if it was seeking to repeat the experience.
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At the time of this experiment, Olds and Milner were concerned that the electrical stimulation they were routinely giving might be aversive (stimulation at many brain sites is aversive, or punishing).
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Effectively, they had discovered evidence of brain systems that may provide the positive emotional consequences associated with natural rewards.
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They had happened upon a phenomenon that has radically changed our approach to motivational mechanisms.
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Intracranial self-stimulation technique?
developed to show that animals will learn operant contingencies (work) to obtain high frequency, pulsed electrical stimulation of specific brain regions. The brain sites capable of mediating this are called pleasure centres.
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What will rats do?
Rats will press a lever many hundreds of times to obtain ICSS. Whatever your definition of reward, this stimulation is clearly rewarding in the sense that animals will work to obtain it. The phenomenon has been found to occur in a number of species
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Beyene, Carelli & Wightman (2010)?
investigated the effects of varying reinforcer magnitude on cue-evoked dopamine release in the NAc shell in rats performing ICSS. Firstly, animals were trained to press a lever for to receive ICSS.
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During testing?
During testing access to the lever was blocked until 2 seconds after cue delivery. The top panel shows the time line for each trial which began with cue onset (2 s prior to lever extension) and ended with stimulation delivery.
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Trials?
Trials were separated by a random interval of 5 s–25 s (as indicated by the dashed line). Centre panel shows a colour plot from a single trial in a single animal (representative trace).
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It displays the transient dopamine activity observed in response to cue onset and stimulation. Bottom panel shows the dopamine concentration extracted from these data using principal component regression are shown.
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Cue-evoked dopamine?
The amplitude of cue-evoked dopamine release in the Nac reflects the magnitude of the predicted reinforcer. This displays representative average dopamine concentration traces for the low, medium, and high reinforcer magnitude sessions from 1 animal.
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Note...
the amount of dopamine released, both in response to cue onset and the electrical stimulation increases significantly with increasing reinforcer magnitude.
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Prediction errors and learning?
Dopamine electrons that show activity (dots on pictures), when the reward is expected but not given there is a suppression of dopamine. (prediction error) Increase in dopamine when reward is predicted and when reward occurs.
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Dopamine and uncertain rewards?
Dependence of phasic neuronal responses on rewards probability.
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Monkey study?
Partial reinforcement procedure, research in monkeys, reward is juice. Reinforcement time is the number of times the reward is given when expected, e.g. the reinforcement time could be 50%.
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This is edited in the experiment, can be seen above what the reinforcement time is. Response to the cue starts to increase with the increase probability that the cue is coming. More dopamine reaction to the cue relative to the reward. (compared to).
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Sustained activation of dopamine neurons precedes uncertain rewards. When the animal is waiting for the outcome (whether the reward is arriving) there is a more sustained response, this is more sustained when the uncertainty is high.
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Interim summary?
Classic work by the group of Wolfram Schultz resulted in a better understanding of the role of DA in reward learning Response to surprising, unexpected reward Increased transfer of DA response from reward to cue with increased learning.
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Pause in DA response when predicted reward is not presented Fiorillo et al.’s (2003) findings were consistent with this But they added a new finding: Uncertainty was associated with a gradual and sustained increase until reward was delivered.
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Role of dopamine in attention-based learning and risk seeking behavior? This was all done in animals. Does this circuitry play an equally important role in humans?
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Dopamine dependent prediction errors in humans? (Pessiglione et al 2006)
Hard to measure dopamine in the human brain, so it is measured in different ways. They found volunteers to take L-dopa or Haloperidol, another group of participants were given a placebo. Reward was monetary gain. 80% of the time a reward was given.
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What did they find?
They found at first people were involved in trial and error but the longer the study the participants realised if they chose the choice stimuli they would receive a monetary reward.
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The group that took L-DOPA (dopamine enhancing)?
The group that took L-Dopa learnt it quicker and were better at maximising the number of points that they want.
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The group that took Haloperidol (dopamine reducing)?
Those on Haloperidol were more likely to sometimes choose a stimulus that was not associated with reward. Role of dopamine in humans seems to have a similar role to that in animals.
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Activation of the brain in this study?
Activation in putamen and ventral striatum (likely to be the nucleus accumbent- we cannot tell for sure so just say the ventral striatum) Responsivity of the L-Dopa group was stronger than the haloperidol.
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What does this show?
This is showing the importance of the putamen and ventral striatum in reinforcement learning and reward learning.
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DA during reward learning?
Similar findings to what has been found in other studies. People were given a smart phone and had to record what they were doing and how much they liked it over a few days. Study was to link the scanner and what can be seen in scans to day to day.
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DA during reward learning associated with reward in daily life (Kasanova et al 2017)?
DA captured with PET imaging. Responses in right caudate and right VST were associated with reward-orientated behavior as measured by EMA over 6 days.
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Summary?
DA in reward and reward-based learning But not exclusively: see very recent findings from de Jong et al.
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Ventral striatum (and putamen) a crucial area within reward-based learning circuitry Role of DA dysfunction in mental health and disorders.
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NEGATIVE AFFECT AND THE BRAIN
NEGATIVE AFFECT AND THE BRAIN
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Who is Papez (1937)?
Papez was one of the first to develop a theory of the brain and emotion He proposes that emotion is not a function of any specific brain center but of a circuit that involves four basic structures.
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What is sensory information split into?
After leaving the thalamus incoming sensory information is split into three streams: thought, movement, feeling He suggested that a circuit including parts of the “old brain” or subcortex, worked together with the cortex to produce emotion.
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First stream?
Incoming sensory information is routed through the thalamus into three different streams: a stream of thought: goes from the thalamus to sensory cortex for further processing of sensory information.
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Second and third stream?
a stream of movement: goes from the thalamus to the basal ganglia (subcortical structures involved in physical movement- part in blue) a stream of feeling: which goes from the thalamus into the hypothalamus.
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Papez's stream of feeling?
Stream of thought and feeling interacted. In Papez’s view, input from the environment is gated through the thalamus to the hypothalamus/
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From there, emotional information is transmitted in two directions: downstream toward the peripheral nervous system and upstream towards the cortex.
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What is the circuit related to?
This circuit is related to emotional stimuli directly “sparking” emotional behavior. This circuit is related to the cognitive involvement - perceptions, attitudes etc., and plays a primary role in the experience of emotion.
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What does the pathway allow?
This pathway allows the mind to “shape” peripheral reactions Projections from the thalamus to the hypothalamus are going downwards into the peripheral nervous system. Gives us energy to behave in a certain way.
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Papez (1937 ) circuit of emotion?
The Papez circuit theory of the functional neuroanatomy of emotion. Papez argued that sensory messages concerning emotional stimuli that arrive at the thalamus are then directed to both the cortex (stream of thinking) and the hypothalamus (feeling).
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What did Papex propose?
series of connections from the hypothalamus to the anterior thalamus (1) and on to the cingulate cortex (2). Emotional experiences or feelings occur when the cingulate cortex integrates these signals from the hypothalamus with information from the SC
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Output?
Output from the cingulate cortex to the hippocampus (3) and then to the hypothalamus (4) allows top–down cortical control of emotional responses. Modified, with permission.
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MacLean's triune brain (1950s-1960s)?
3 brain systems, each developed in a distinctive phase of evolution: Reptilian brain (“R-complex”) Paleomammalian (“limbic system”) Neomammalian brain (“neocortex”).
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What is the reptilian brain?
oldest brain, includes brain stem and the cerebellum in animals such as reptiles, the brain stem and cerebellum.
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Limbic system and MacLean?
MacLean as the person who introduced “limbic system” MacLean pointed out that emotions are sophisticated, constructed by complex interactions involving the three layers, the three “brains”.
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”. He emphasizes the importance of considering the evolution across species, has a functional view of emotion (cf. Darwin). He introduced the term “limbic system”, his model is largely refuted.
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Note?
Though several structures within limbic system are important for emotion, it is too simple to consider the limbic system as the “seat” of emotion.
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Where is the limbic system?
Area just above the corpus callosum, not everyone agrees with the limbic system and where it is, but they believe in all the other structures in the brain.
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Kluver-Bucy syndrome? (1937)
large lesions inferior temporal lobe affected visual association cortical areas, amygdala, hippocampus Symptoms were manyfold, including a change in emotional behavior- lack of fear, lack of defensive behaviour including aggression.
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LeDoux (1980s onwards)?
Rat put in a cage above a grid, after sound electric shock in grid. Rat would then associate these together. Freezing behaviour shows fear in animals. The freezing behaviour starts to get transferred onto the CS, and rat shows fear to the sound alone
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What happened?
Fear conditioning did not take place when the amygdala was lesioned Furthermore, with simple tone and shock, only the connection between thalamus and amygdala is sufficient for fear learning and fear responses.
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What does this show?
Amygdala lesions abolished fear conditioning, showing amygdala is most likely the site of fear conditioning.
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LeDoux's model (1994)?
Subcortical pathway (“low road”) is crude but fast Cortical pathway (“high road”) is precise but slow.
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Auditory fear conditioning pathways?
CS pathway; CS- auditory thalamus- auditory cortex. US pathway- US- Somatosens Thalamus- Somatosensory cortex. Lateral nucleus of the amygdala: information input. Then transmitted (via basolateral nuclei) to central amygdala for response output.
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What about human studies on the Amygdala? (Adolphs et al 1994)
Patient SM: bilateral amygdala damage, SM 30 years, normal intelligence. Had Urbach-Wiethe disease. Had trouble recognizing facial expressions of fear generating the facial expression of fear drawing an expression of fear.
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Bechara et al (1995)?
SM exposed to conditioning She did not show responses to either CS (as indexed by SCR) But she did show SCR to the US, and could accurately describe the images.
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Inman et al (2018) amygdala stimulation study?
Stimulation of amygdala vs control region: Participants showed increases in SCR amplitude commensurate with voltage of stimulation.
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However?
But only two participants experienced emotional changes, of which one experienced some laughter and also panic during bilateral stimulation.
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One of these two participants reliably showed changes in subjective experience when either left or right amygdala were stimulated (see video in the article).
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How to image the human brain in action?
MR Scanner, Functional magnetic resonance imaging (FMRI or fMRI)
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Whalen (2005) amygdala response to eye whites?
All subjects unaware of seeing eye whites, amygdala activity greater for fearful eye whites than all other conditions.
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Facial expressions?
Facial expressions are complex configural stimuli; this demonstrates a simple rule that could be used ready response systems for the potential outcomes predicted by this rule, think back to LeDoux's 2-road model.
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Amygdala conclusions?
The amygdala also plays a role in emotion perception and expression in humans The amygdala is related to fear/threat, but also with other negative (as well as positive!) affective states.
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LeDoux’s pathways serves as a powerful model of emotion processing Role of the cortex in inhibition? => more next week!
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Gallagher...Role of amygdala in reward, incentive values of goals Current focus more on cognitive ageing.
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SEE SLIDES
FOR MORE QUESTIONS
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EMOTIONAL REGULATION
AND THE PFC
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What is emotion regulation?
Emotion regulation consists of the intrinsic and extrinsic processes responsible for monitoring, evaluating, and modifying emotional reactions, especially their intensive and temporal features, to accomplish one’s goals. Thompson, 1994
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What are some regulation-relevant processes?
Extinction, cognitive change:reappraise the situation, attentional deployment, habituation, distraction through means other than attention.
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Which regions are involved in all this?
PFC- ventromedial PFC, dorsolateral PFC, ventrolateral PFC and amygdala. Dorsolateral PF- involved in working memory.
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Amygdala role?
Key role in detection of significant, potentially threatening information (Davis et al 2001), activation of the sympathetic nervous system (arousal) and responding to negative situations in general, as per FMRI studies.
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What in this studies?
Facial expressions of emotion- fear and surprise particularly, negative pictures.
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What is extinction?
A very basic type of emotion regulation, conditioned fear responses to a tone previously paired with a shock diminish if the tone is repeatedly presented without the shock, a process known as extinction.
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Continued...
Not a process of "unlearning" but of new learning of fear inhibition, conditioned response can return after extinction (e.g. spontaneous recovery, reinstatement, renewal).
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Animal research on (v)mPFC? (Morgan & Ledoux 1995).
Early research in LeDoux's lav shows that the mPFC is involved in modulating emotional response, mPFC lesioned rats show emotional reactivity (freezing) to the CS and contextual; stimuli during both acquisition and extinction phases.
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Update on this?
Exposed animal to classical conditioning, they noticed that animals that have a legion in the (v)mPFC show freezing behaviour more than those without a legion in this area.
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Milad and Quirk 2002- rat study?
Rats given auditory fear conditioning, 30s tone paired with footshock on day 1. Freezing increased during conditioning in day 1 but reduces during extinction. Unit recording electrode in infralimbic cortex (vmPFC).
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What do neurons respond to?
These neurons respond to the tone CS only in the delayed test of extinction. Not during conditioning or initial stages of extinction.
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Extinction of fear learning in humans? Phelps et al. (2004).
One of the first studies to look at the extinction of fear learning in humans. They show a blue square with an electric shock, yellow square was a control. In extinction the blue square was shown without an electric shock.
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Acquisition shows blue square with electric shock showing high skin conductance, lighter grey is yellow square. Day 1 shows the blue square with no electric square, showing a lower skin conductance.
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Day 2?
Day 2 shows the blue square with electric shock to start and then blue square without electric shock.
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Results?
Response in vmPFC during day 2 extinction recall correlated with the success of extinction training on day 1 (measured by skin conductance response SCR). Consistent with a role for the vmPFC in the retention of extinction learning.
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Milad et al. (2005) study on humans?
They found thickness of ventromedial PFC is correlated with extinction memory.
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Amygdala activation?
Acquisition- CS+>CS-, Early extinction: CS->CS+, Extinction retention: no differential activation. During acquisition and early extinction CS+-CS- activity in amygdala correlated with Cr (measured by SCR). (Phelps et al 2004)
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No correlation between subgenual anterior cingulate (vmPFC) response and CR during acquisition or early extinction. Subjects who showed more extinction on day 1 showed more subgenual anterior cingulate activation at the beginning of day 2 extinction.
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What is this consistent with?
Consistent with role in retention of extinction memory.
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mPFC during extinction?
Lesions to vmPFC impair fear extinction (Morgan et al 1993), damage to vmPFC impairs the retention of extinction learning (Milad & Quirk 2000), stimulating vmPFC produces extinction (Milard 7 Quirk).
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vmPFC activation in extinction correlates with extinction success (in humans; Phelps et al., 2004), mPFC- amygdala interactions play a key role in extinction.
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What is the ventromedial prefrontal cortex (vmPFC)?
Involved in fear extinction learning in animals and humans, fear extinction learning suggests correlation between vmPFC and amygdala.
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Continued...
Strongly anatomically connected (Barbas 2002), inverse coupling of vmPFC and amygdala during extinction of conditioned fear response.
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What is reappraisal?
The process where we assign a different stimulus to an object and changed emotional response.
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Experimental work on regulation through reappraisal? (Urry 2006)
Decrease: focus on less intense outcome, objectify the situation. Increase: focus on more intense outcome, personalise the situation. Attend: maintain attention to the slide.
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Amygdala response during explicit regulation?
When people boost emotional response they can enhance amygdala response, compared to when people decrease emotional response the amygdala response inhibits.
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vmPFC during explicit reappraisal?
Negative correlation between vmPFC and amygdala during reappraisal.
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vmPFC- amygdala circuit sufficient?
Emotion regulation involves a lot of processes, not all of which the vmPFC is involved in. Lateral and dorsal PFC are not strongly anatomically connected to the amygdala, but the vmPFC is. The vmPFC is also connected to lateral and dorsal reg of PFC.
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What are the areas in emotion regulation also connected to? (Ochsner et al 2004)
Cognitive control or executive functioning (dIPFC), vIPFC well connected with dILPFC, strong anatomical and functional interactions with other areas of PFC. Those involved in executive functioning are also involved in emotional regulation.
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What is a crucial part in the amygdala?
dIPFC, vIPFC, vmPFC and sensory and association cortex. Encoding of hippocampus is also starting to play a role but is still being highly investigated.
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Conclusions?
Amygdala receives input from a multitude of regions vmPFC has direct anatomical connections with amygdala animal and human research confirm functional connections in regulation.
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Continued...
vmPFC connections with lateral PFC important for goal-directed behaviour and hence (complex) emotion regulation Mediated by the vmPFC.
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SEE SLIDES
FOR QUESTIONS
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PERCEPTION
ATTENTION
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Information processing and the brain- the illusion of vision?
We look around the environment around us and it seems as if everything is clear and well defined, the things we see, feel and touch everything around us. In reality this is not the case, the brain selectively processes sensory information.
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Why?
It does not have capacity to process all information.
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Traditional brain sketch?
Felleman and van Essen (1991)- diagram of wiring of brain, lot of different wires/lines, what was connected to what, what passes information to what and what is processed.
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Flow control and modules?
Air con unit diagram, same is true for the brain just on a different level. Brain is very different to a computer as biological processing system (cortical structure). There are different lobes of the brain/
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Different cortex?
Parietal cortex, occipital cortex, temporal cortex, frontal cortex and cerebellum which is involved in movement.
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What is phrenology- Franz Joseph Gall (1758-1828)?
The idea that specific behavioural attributes can be spatially localised to specific regions of the brain, that the mind can be described in terms of distinct "mental faculities" each localised in a "specific brain organ".
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What does this out of date philosophy suggest?
Suggests lumps and bumps on the head describe shape of brain, however it did suggest that specific areas of the brain do specific things. This is still relevant now.
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Why can't all information be processed?
Physiological constraints- brain is 5% of our body mass, but accounts for 20% of out energy consumption. Energy supplied to the brain is sufficient for 1/60 neurons to be highly active at a given moment in time.
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Another reason?
Processing constraints- the brain simply could not process all of the available sensory information, it is quiet a significant amount of time. Analogous to the limits of processing on a mobile phone. The brain and a computer are both processing info.
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Broadbents (1958) "filter theory" of selective attention?
Information processing in the brain has limited capacity, the brain must be selective about what it processes, this selective processing was termed "filtering". Allows the brain to process only things that are important.
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Explain the method?
Information goes to the left and right ear and through the sensory buffer. the left ear then filters this information, whereas the right does not and it goes into the short term memory.
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Treisman (1969) attenuation model?
Attenuation of information, not all or nothing like Broadbent suggested. We dampen down everything else, but do not completely ignore it. For example, the left ear will not listen at that point but it will still go into our short term memory.
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What is the key point to both models in terms of attention?
Attention acts to reduce the amount of information to be processed.
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Types of attention?
Modal Attention: attention to a specific modality Spatial Attention: attention to a spatial position in the world Temporal Attention: attention captured by things at a specific time point.
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Continued...
Feature Search: in relation to feature integration theory Object-based attention: attention to items which are classed as an object.
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Modal attention; Spence, Nicholls and Driver (2001)?
Auditory, visual or tactile stimuli all randomly interleaved Participants told to expect (1) auditory, (2) visual, (3) touch, or (4) any Participants asked to respond “left” or “right” and reaction times measured.
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Continued...
People have to detect a stimuli on left or right, can be in different forms. Task is always the same. Set up to see if we focus on a particular type of attention like auditory or just general attention.
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Results?
RT’s are improved when responding to a signal in the expected modality relative to to the unexpected This is due to a cost (in terms of time) for responding in the unexpected modality. The type of attention told to focus on has quicker RT.
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What is this due to?
This is due to not boosting attendant, but dampening down process of unexpected modality.
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Spatial attention; inhibition of return experiment?
Fixating in the centre of a screen and different texts on left or right. One of these locations will be cued.
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Results?
The cue facilitates detection of the target at short cue-target-onset-asynchronies- The amount of time between the cue and target appearing (CTOA) But inhibits detection of the target at long cue-target-onset-asynchronies.
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Overall?
Harder to detect stimuli in cued location at shorter times than longer.
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Spatial attention; visual acuity and peripheral vision experiment?
When at approximately normal reading distance, all letters should be equally eligible (like an eye test). This is due to the drop-off of visual acuity with increasingly peripheral vision.
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Spatial attention and "crowding"?
There is a red cross and then the word 'eyes' and then a blue cross and then the letter 'y'. If you fixate on the red cross and see if you can see the Y in EYES it will be very difficult, if not impossible.
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What about the blue cross?
If you fixate on the blue cross and do the same, this will be much easier. Spatial attention i slimited by more than simple acuity.
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Temporal vision and attentional blink experiment?
List of letters one in a different colour, target 1 (that letter) captures attention and the next letter (target 2) is harder to detect.
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What is RSVP?
Rapid serial visual presentation- when an item captures attention e.g. by being a different colour, the subsequent target is harder to detect/ identify.
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However?
Only when the gap between letters is 200-400ms. This is called the "attentional blink". Cause: thought to be competition for resources and inhibitory processes.
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What is feature search and conjunction search? (Williams et al. 2014)
When a target object is specified by a single feature, RTs remain constant regardless of the number of distractors. E.g. a blue cross in a group of red circles and crosses. Looking for blue.
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Conjunction of features?
RTS linearly increase as the number of distractors increases, e.g looking for a blue x in a group of blue circles and red crosses.
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What theory was proposed to explain these results?
Feature intergration theory (Treisman et al)
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What is feature integration theory (FIT)?
Difference (dichotomy) between 1. "pre-attentive" processing of features in parallel (responsible for feature search), 2. "attentive" serial processing requiring focal attention (responsible for conjunction search).
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However?
This distincton does not map cleanly onto the features which are known to process early and late in the brain. Modifications to this theory have been proposed- some maintain the parallel versus serial distinction, others not. This is still debated.
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What are perceptual objects?
A collection of parts or components which are treated as a single object.
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What is object based attention? (Kahneman, Treisman and Gibbs 1992)
They proposed that object-based attention involves the creation of "object files". These are a temporary representation which contains information about the attributes of a given "object", e.g. position, colour, shape, etc.
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What is one way in which object-based attention has been studied?
Multiple object tracking (MOT) (Phlyshyn and Storm 1988). List of instructions and about 85% accuracy when tracking five target disks among 10 identical items.
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What does attention increase in the brain?
Attention increases the firing rate of neurones to a given visual feature (Motter 1993).
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Continued...
Same enhancement is try for other senses e.g. taste and smell. However, as one might expect, given the diverse manifestatins "attention" there is no single brain area resposible for attention.
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What is attention an intergral part of?
Instead, attention is an integral part of sensory processing for all modalities.
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VISION
VISION
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What is so difficult with vision?
The world is 3D, but our eyes only see two 2D projections of the world. The results of projecting from 3D to 2D is a loss of information.
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What does the brain do in the 3D world?
To perceive and act in the 3D world, the brain has to somehow infer the 3D structure of the world from these 2D images and how they change over time.
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How does it do this?
It does this by using “depth cues” in the images These are quasi-separable sources of sensory information which carry information about the 3D structure of the world.
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What are the key goals of vision?
Determine which surface are in front or behind another, estimate the depth between surfaces e.g. size of an object, estimate the distances to points in the scene, estimate the surface shape of objects in the scene. (for perceiving and actingin world)
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What is the summer vision project?
The summer vision project is an attempt to use our summer workers effectively in the construction of a significant part of a visual system.
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Continued...
The primary goal of the project is to construct a system of programs which will divide a vidisector picture into regions such as likely objects, likely background areas and chaos. Still unsolved.
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What is a monocular (pictorial) visual cue?
These are available to each eye independently i.e. close one eye and you still have these cues. Note: you have monocular cues when both eyes are open, they do not disappear.
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What is binocular visual cues?
These cue are only available from the fact that we have two eyes and that parts of the world can be seen by both eyes at the same time.
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Monocular- what is occlusion?
Occlusion provides information about the depth ordering of surfaces, but not the depth between them or their absolute distance.
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Monocular- what is relative size?
If we know the size of objects in the scene, it is possible to infer their distance from the angle subtended at the retina.
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Monocular- what is perspective?
Provides information about distance in the scene, closely related to texture.
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Monocular- what is texture?
. The width and shape of the texture elements changes with distance. The density in the image also increases Texture can provide information about properties such as surface orientation.
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Monocular- what is blue (focus cues)?
Like a camera, the eye has a depth of field. Points laying nearer or further than the focus point appears blurred.
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Monocular- what is shading?
With knowledge about the lighting direction and type of surface the pattern of light and shade on a surface can provide valuable information about surface shape.
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Monocular- what are shadows? Mamassian, Knill and Kersten (1998).
, the motion of the ball in the two instances is identical The only different is the rendering of the shadow.
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What does the ball look like?
In one instance the ball looks as if it is moving laterally across the room but going up/down in the air In the other, that the ball is moving diagonally across the room near to the floor.
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Monocular- light from above?
A key thing to understand is that cues can be ambiguous about the underlying structure of the world. For example our brain assumes that light is coming from above and uses this to interpret the pattern of light and shade.
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Monocular- what is motion parallax?
Motion provide an important cue to 3D properties such as shape This cue can be provided by the object itself moving (as in this demo) or the person who is viewing the scene moving Closely related to “optic flow”.
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Experiment example?
Lots of small blue dots, a few larger yellow dots. Blue dots will move, yellow will not. Yellow dots will occasionally vanish either together or separately. Motion in the background is affecting our perception.
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Monocular- motion induced blindness?
If you make the dots more visible in the image, it makes the allusion easier to see. Fuzzy sensory input- link to attention that not all information visual to the attention system can be used.
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What are pictorial visual allusions?
Strong example of how cues can be manipulated to induce the perception of depth and 3D structure where there is none For example, the street artist is exploiting a number of cues such as perspective, relative size and textural cues.
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What is the artist using these cues to simulate?
A large drop- see slides for image.
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What is the key things with illusions?
They can only be viewed from a specific view point to work. Only work from one angle, the illusion is contingent on a specific viewing position.
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Are there really failures of vision?
Pictorial illusions such as this initially seem like dramatic failures of vision However, the visual system is in fact doing something very sensible here It is exploiting sensory cues, which would in any other situation provide veridical (“correct”).
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Binocular visual cues?
Arise form the fact that we have two eyes with overlapping fields of view Each eye gains a slightly different view of the scene The differences between the eyes views are termed binocular disparities.
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Why are these cues important?
They are considered particularly important as theoretically they can be used to fully estimate the 3D structure of the scene.
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What is Ames room?
Visual illusion dependent on the elimination / weakening of binocular cues.
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Continued...
Setup such that from a given viewpoint monocular cues suggest that the room is rectangular In reality the room is not rectangular and the tiles on the floor are not square Binocular visual cues would tell us the “true” shape of the room.
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Patrick Hughes- reverse prespective art? What is it?
Reverse perspective art is another example of where different types of visual cue can be put into conflict with one another.
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Example?
, perspective and other cue are signally a completely different 3D structure to binocular and motion cues Illusion is so strong that it overrides our assumptions that objects are rigid and do not distort as we move relative to them.
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Cues and domains?
Different cues have different domains of utility (Cutting 1997)- X axis has distance and Y axis had strength of visual cue, occlusion is good.
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Disparity vs Distance?
High disparity (Y axis) is strong and longer distance (x axis) is weaker. Horizontal disparity produced by a 5cm depth object at a range of distances.
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What did Rgers and Gyani (2010) look at in terms of reverse perspective art?
Want to see what properties change the strength of the illusion. First looked at texture, illusion is equally strong in different textures.
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Continued...
Got people to look at art monocularly or binocularly. Also, change distance from art work. Were looking at when the artwork flipped. Regardless of the texture you have to get much further away from the artwork when you have binocular vision vs monocl
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Continued...
for the artwork to go in its illusion state. Further away from the artwork our binocular views become weaker.
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PERCEPTION AND ACTION
PERCEPTION AND ACTION
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What is the dorsal stream?
V1-V2-V3/V3A-MT-MST- Areas of parietal lobe.
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What is the ventral stream?
V1-V2-V4-IT-PIT/AIT-Areas of temporal lobe.
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What is the ventral stream used for?
Processing information that tells us about form, colour and identify of objects. Damage forms deficits.
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What deficits does the ventral stream form?
Prosopagnosia: inability to recognise faces (Bodamer 1947; Kanwisher et al 1997) Achromtopsia: cerebral colour blindness (Pearlman, Birch & Meadows 1979) Visual form agnosia: deficits in object perception (Milner and Goodale 1995).
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What is the dorsal stream used for and deficits?
Processing information about the spatial layout of objects and object motion. Motion blindness: inability to see object motion (Zihl, Von Cramon, Mai 1983) Optic ataxia: intact recognition of objects, but motor problems interacting with them (Mil 95)
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Where are these streams (Cortical visual systems) ?
Dorsal steam: specialisation for spatial vision (“where”) Ventral stream: specialisation for object vision (“what”) Based upon selective deficits in perception that result from damage to areas in each stream (esp. in monkey).
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Subtitle
VENTRAL STREAM PROCESSING
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Subtraction methodology?
One way in which information processing can be studied using brain imaging.
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What is fMRI?
fMRI- way to localise images from the brain. Have to compare two conditions. By taking a contrast we can find out what specific brain regions our related to the processing of our two tasks. This is the subtraction methodology.
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What is the fusiform face area?
Kanwisher et al. (1997)- areas of the brain that focus more on faces than objects (1a) compared to 1b that is areas of the brain focused more on objects than faces. SEE SLIDES. Damage to this area links to prsopagnosia.
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What is prosopagnosia?
Face blindness- may see a face clearly but can not identify them. For example, may not recognise their partner or best friend.
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What else is used rather then fMRI?
In addition to imaging techniques such as fMRI, some of the strongest evidence for functional specialisation comes from analysing function after accidents causing localised brain damage. (Goodale and Milner 2013)
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However?
However, the loss of function after brain damage is one extreme of a natural gradation of function across people. Sections PPA (places), FFA (faces) and area of Localisation is objects.
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Subtitle?
DORSAL STREAM PROCESSING
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What is a widely studied area?
Cortical MT/V5- Damage bilaterally results in a condition where one is unable to see motion.
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Example of this?
patient who suffered bilateral posterior brain damage. Had difficult in life, for example not being able to cross the road. The way she perceived motion, pouring water into a cup and not knowing when to stop as looked like snapshots all the time.
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Explain cortical area MT/V5?
MT studied widely in the macaque monkey and humans Highly motion selective but also highly selective for 3D properties such as depth Columnar structure of motion and depth selectivity, we have functional localisation to specific directions.
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Subtitle?
VISUAL FORM AGNOSIA
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What is it?
Inability to identify objects and object properties such as orientation, intact factial perception. For example, can recognise picture of Albert Einstein but not a scrubbing brush. Although, can recognise they are able to interact with them daily.
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What did Milner and Goodale (1995) propose?
the ventral and dorsal streams could be better classified as for ‘perception’ versus ‘action’.
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Evidence?
Much evidence based on a patient DF who had localised brain damage following carbon monoxide poisoning resulting in ‘visual form agnosia’.
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Is this a good theory?
Hugely influential theory, but very controversial Especially as regards the demonstration (or not) of the disassociation in neurologically intact individuals.
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Goodale and Milner (2013) experiment?
First task is matching orientation of letter box with object in hand. (perception) Second task is posting it through the letter box. (motor control). With visual form agnosia they are much better at posting the letterbox than matching it up.
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Explained?
Cannot recognise simple objects e.g. orientation of a line, but can direct accurate actions to those same object. Another experiment was copying an image and then doing it from memory.
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Results of this?
Cannot recognise and copy a simple line drawing, but can draw from memory.
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What about when objects are put with visual cues?
Patients have no problems at all.
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Where is visual form agnosia affected in the brain?
Visual form agnosia caused by damage ventral stream visual areas. In patient DF dame is largely localised to the position of area LO.
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Studying action in an fMRI scanner?
In the same way as specific areas for components of vision, specific areas for components of action have been identified. LIP is saccades, AIP is grasping and PRR is reaching.
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Subtitle
OPTIC ATAXIA (reverse pattern to visual form agnosia).
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What is optic ataxia?
Problems with visually guided action e.g. reaching to grasp an object and orientating the hand.
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Balient's syndrome?
One of the three primary deficits of Balint’s syndrome, which additionally consists of Inability to perceive the visual field as a whole (simultanagnosia) Difficulty in fixating the eyes on an object (oculomotor apraxia).
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Where is the damage?
Damage to dorsal visual areas. Inability to visually guide action, reaching out to grasp an object for example.
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What can the deficits in visually guided action not be attributed to?
Visual field deficits Deficits in visual acuity General motor control problems Somatosensory deficits Optic ataxia is caused by damage to dorsal stream visual areas.
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Dorsal stream and the control of grasping?
Poor reshaping of the hand to the properties of the object Selection of unstable grasp points For example, the highlighted grasp point is not a stable way in which to pick up the object.
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In contrast?
In contrast, a person with visual form agnosia would have no problems with these types of task.
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Dorsal stream and obstacle avoidance?
Which processing stream is responsible for object avoidance during movements such as reaching? Two tasks Reaching between obstacles Pointing at the position between the same obstacles (bisection).
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Which patients did they test?
Tested patients with optic ataxia and neurologically intact individuals.People with optic ataxia ignore obstacles when planning reaching movements, but at the same time can accurately bisect the distance between them.
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Who created the term double dissassociation?
Hans-Lukas Teuber (1955)
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In terms of visual form agnosia?
Damage to ventral stream, problems with conscious visual perception by not motor control.
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In terms of optic ataxia?
Damage to dorsal visual stream, problems with motor control but not conscious visual perception Powerful form of localising and separating function.
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TV example from Parkin (1996)?
If your TV set suddenly loses the colour you can conclude that picture transmission and colour information must be separate processes (single dissociation: they cannot be independent because you cannot lose the picture and still have the colour).
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On the other hand?
If on the other hand you have two TV sets, one without sound and one without a picture you can conclude that these must be two independent functions (double dissociation).
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INDIVIDUAL DIFFERENCES
INDIVIDUAL DIFFERENCES
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What are weird popultations?
Experimental studies on perception and sensation usually involve participants from WEIRD populations Western, Educated, Industrialised, Rich, and Democratic.
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What can this lead to?
This could lead to bias and difficulty in generalising to the population as a whole Stable individual differences in response patterns across perceptual and cognitive tasks.
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Different factors?
Demographic factors Age, gender, culture etc. Morphological variability of sensory cortices One example we will discuss is differences related to area V1 Psychological constructs Anxiety, impulsivity, etc.
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Why the bias?
Most human behavioural experiments are conducted at universities Many on students in psychology or neuroscience classes Demographics of psychology students 2/3rds of students are <24yrs of age The majority of psychology students are female.
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What can the study of individual differences be pictured as sitting between?
Basic science tends to study the “average” behaviour of a group of individuals and compare groups Clinical science tends the extremes of variation in the population The remaining variation is typically treated as “noise” i.e. a nuisance variable/
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What does it aim to do?
Individual differences research aims to examine the natural variability which characterises us.
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Twin studies?
Variability can be due to genes and environment Twin studies allow you to determine the relative importance of these.
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Monzogynotic twins (identical) vs dizygotic twins (non-identical)?
MZ: Share 100% the same genes and the same environment DZ: Share 50% the same genes (no more than siblings) and the same environment Allows one to examine the extent to which individual differences are caused by “genes” versus the “environment”.
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What is the cambridge face memory test (CFMT) (Wilmer et al 2010)?
Learning phase: in which you see a series of faces Testing phase: Identify which of the faces you have seen before.
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Twins results in this test?
MZ: Monozygotic twins (“identical”) - 100% DNA shared DZ: Dizygotic twins (“non-identical”) - 50% (no more than siblings) High family resemblance in face recognition ability, most of which can be attributed to genes rather than environment.
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Vision test?
Visual acuity (the ability to resolve fine spatial detail) improves over the fist year of life but does not reach adult levels until age 4 or 5. In the later decades of life, there is more gradual decline in performance.
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Continued...
Even a 90-year-old's acuity is five times better than that of a 6-month-old infant.
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Infant studies vs adults?
When we compare data from infant studies against data collected from adults at various ages, a general pattern emerges of rapid early improvement followed by gradual decline.
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What trend does performance generally follow?
U-shaped function with optimal performance during the late teens and early twenties. The graph is plotted so that smaller Y-axis values correspond to better task performance.
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Age and visual acuity?
Perceptual abilities, such as visual acuity, are observed to change across one’s lifespan Comparisons between infant studies and data collected from adults, demonstrate rapid early improvement in perceptual capabilities followed by a gradual decline
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Why do babies have poor vision?
Cannot be attributed to optical defects (aberrations) The accommodation of a babies eye is however relatively inaccurate.
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Why does infant acuity improve so dramatically, and what underlies the decline in later life?
The new-born eye is relatively free of optical defects, though accommodation is relatively inaccurate (Atkinson, 2000).
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Older adults and poor accomodation?
This is due to the lens progressively hardening with age With this hardening it can no-longer change shape to focus the image. After a certain age the eye can effectively no-longer accommodate.
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Why does visual acuity show a decline later in life?
Reduced mobility of the pupil causing the pupils in elderly observers to remain quite small even in dim illumination, with consequent reduction in retinal illumination.
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Continued...
Increased light absorption by the lens (senile cataract), reducing retinal illumination Degeneration of the central retina Photoreceptor loss due to the disappearance of the retinal pigment epithelium results in a progressive loss of central visio
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Age and olfaction?
Allows the detection of fire, dangerous fumes and pollution in the env (therefore, acts as a warning system). importantly it also determines, the flavour and palatability of food and beverages.
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Dory et al (1984)?
Doty et al: essentially examined the nature and degree of age related changes in smell. Used a microencapsulated test of olfactory function, which included 40 odours. Forced choice task.
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Results?
Females seemed to outperform men in general. Non-smokers performed better than smokers. Average ability shows a peak between 20-40 years followed by a slight decrease in the 6th and 7th decade and quite a dramatic decrease after the 7th decade.
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In terms oe memory?
Not correlated with tests of memory - decline in performance is therefore not simply due to people having problems with remembering the names of odours. Probably why many elderly persons complain about food lacking in flavour.
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When is odour identification greatest?
Odour identification is greatest between the 3rd and 5th decade of life and declined after the 7th Could be due to degeneration/damage of the olfactory receptor epithelium?
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Causes of these changes?
aren’t well understood, but could be linked to degenerative processes of the olfactory system, including reductions in the efficiency and number of olfactory receptor neurons. This could perhaps be a result of viruses and chronic inflammatory disease
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Other studies?
Histological studies of human and rodent olfactory epithelia and olfactory bulbs have reveal striking differences between old and young specimens.
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Murphy et al (2002) experiment on age and olfaction?
examined the prevalence of olfactory impairment in older adults Sample size: 2491 / age range: 53-97 Prevalence of olfactory impairments were greater among men and overall impairments increased with age. 62.5% of 80-97 year-olds showed impairment.
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Two point discrimination tasks and touch?
Discriminate whether a region of the body e.g. foream, palm or finger is being touched by two verses one point. Age related changes in tactile sensitivity.
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Shimokata and Kuzuya (1995) study on two point discrimination?
The subjects were 2,036 men and women aged 10-87 years. Measured two-point discrimination An age-related decline in the ability to discriminate two points was apparent.
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Continued...
No significant differences in ability between men and women. The minimal distance of discrimination on the hand increased almost linearly between 10 and 60 years of age.
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Gender differences?
Females have been found to outperform men in auditory and somatosensory tasks (better tactile acuity, better tone sensitivity as well as taste sensitivity).
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Cognitive measures?
Research has also shown a female advantage on cognitive measures of verbal memory and social cognition. Males on the other hand have been found perform better on navigation and mental rotation tasks.
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Gur et al (2012) experiment?
examined age-group and sex differences in a variety of cognitive functions. Administered participant with battery of neurocognitive tests which included a total of 14 tests that examined 5 different neurobehavioural functions.
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Reading test?
A brief standardized reading test from the Wide Range Achievement Test (WRAT4, Wilkinson & Robertson, 2006) was administered first to determine participants' ability to complete the battery and to provide an estimate of IQ.
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Results females?
Females performed more accurately and faster on attention, verbal and face memory tests as well as on all social cognition tests Better performance on emotion processing and social cognition.
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Results males?
Males performed better on the spatial processing and were faster on the sensory motor and motor speed tasks.
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Gender and memory- Andreano and Cahill (2009)?
): reviewed literature on classes of memory tasks for which sex differences have been observed; spatial memory, verbal memory and autobiographical memory.
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Results?
, males were found out perform females at tasks involving spatial memory while females showed an advantage in verbal memory Sex differences in spatial memory for men seemed to be restricted to tasks that involved a mental representation of space.
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Culture? Muler-Lyer Illusion?
: the perception that a line ending in inward-pointing arrows is longer than a line ending in outward-pointing arrows.
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Segall et al (1963)?
): examined susceptibility of the Müller-Lyer illusion in urban and tribal participants in USA, Africa and the Philippines Results indicated that Urban participants showed greater susceptibility to the illusion Carpentered environment hypothesis.
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Deregowski (1989)?
Participants from Western societies and an African Bantu tribe were asked to interpret this image.
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What do they show?
Shows cultural variations in depth-of-field perception Susceptibility to optical illusions seem to depend upon visual experiences in the environment and how these experiences are interpreted across cultures.
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Gray matter over age?
Gogtay, et al (2004) Thirteen healthy children: anatomic brain MRI scans were obtained every 2 years, for 8–10 years Cortical gray matter development between the age of 4–21 years using quantitative four-.dimensional maps and time-lapse sequences
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Continued...
Four dimensional: three spatial dimensions, but also over time Time-lapse “movies” of how the brain develops with age This done by aligning know landmarks of the brain over each timepoint.
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Brain differences?
There is evidence suggesting that the surface areas and volume of V1 varies across individuals.
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Schqarzkopf et al (2010)?
examined morphological variability in V1 and how this influenced visual perception using the Ponzo and Ebbinghaus illusions.
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Individual differences in the amygdala?
Stein et al. (2007): Examined the role of high and low anxiety on amygdala activity using an emotion processing task.
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Results?
Participants with increased anxiety had significantly greater bilateral amygdala and insula activation to emotional faces.
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NOTE?
Powerpoint and reading includes more information for potential essay questions. Make sure to look at these.
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