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Each muscle fibre is activated by just one (lower) motorneuron...
...but each (lower) motorneuron connects to many muscle fibres
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Action potentialls starting in he spinal cord/brainstem reach the neuromuscular junction, what happens here?
Acetylcholine is released from motor neurons and binds to receptors at the end plate of the muscle fibres. Action potentials are then made in the muscle surface membrane.
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What happens when action potentials are made in a muscle's surface membrane?
Calcium ions are released from the muscle's internal store allowing actin and myosin to interact (slide over one another) so the muscle can contract.
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What happens when acetylcholine is released from motorneurones at the neuromuscular junction but there are abnormal muscle proteins?
Duchenne muscular dystrophy
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What happens when acetylcholine transmits a signal at the neuromuscular junction but there are abnormal receptors to meet them?
Myasthemia Gravis (muscles are very weak)
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What happens when acetylcholine receptors are blocked at the neuromuscular junction and how can this come about?
Become paralysed. This happens when use anaesthesia and it is what south americans did using curare
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What does the strength of muscle contraction depend on/
The number of muscle fibres activate simultaneously
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For each action potential reaching a muscle there is...
One muscle twitch
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What happens there there are a train of action potentials separated by time reaching a muscle?
A sequence of muscle twitches
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What is a tetanic contraction?
Large prolonged contractions where each action potential arrives with 10-100ms of the last one
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Muscle contractions are said to be...
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Lower (alpha) motorneurones are said to be the last part of the brain to initiate movement. Where do they begin?
The brain stem and spinal cprd, the are the final neurones before muscles and they maintain the structural integrity of muscles
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Are lower motorneurones large?
Yes, they're fast too
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What is located in the spinal cord that can lead to movements?
Central pattern generators
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How can lower motor neurones be damaged and what does this result in?
By cutting the peripheral nerve via polio or alcohol abuse you can get lower motor neurone syndrome
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What are the symptoms of lower motor neurone syndrome?
Paralysis, flaccid muscles, muscle wastage, no reflexes. You can also get too much acetylcholoine which leads to spontaneous contraction (fasticulation) and fibrillation of the cardiac muscle!
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Where do upper motorneurones start?
In the primary motor cortex, premotor cortex and supplementary motor cortex
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What sets the resting tone of all muscles?
The rhesticular spinal pathway (goes from spinal cord to rheticular formation: pons and medulla oblongata)
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What are upper motorneurones neccessary for?
making voluntary movements
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What do upper motorneurones innervate?
Lower montorneurones
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What happens when upper motorneurones are damaged?
Unable to make reflexes or voluntary movements, ******* paralysis and increased muscle tone resulting in permanent contraction
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What neurones tell lower motorneurones what to do?
Upper motorneurones, sensory neurones, neurones controlling posture
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What do upper motorneurones do?
Modulate reflex strength
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What can central pattern generators do?
By using local circuits can result in learnt sequences of movements independent from the cortex that can be as complex as swimming
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What does motorneurone disease generally refer to?
Lower motorneurones
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What happens when a stroke affects the motor cortex?
Upper motor neurones degenerate
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What does the primary motor cortex contain?
The motor homonculous
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What is the overall role of the basal ganglia?
For gating the initiation of movements
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What is muscle weakness a sign of?
Lower motor neuron damage
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What is spastisity a sypmotom of?
Upper motor neuron damage
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Who was the 1st to suggest there must be an orderly organisation of motor representation in the brain?
A Yorkshire physician
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What did the "Jacksonian march" of seizure activity running accross the body surface show?
That the representation of the body runs across the primary motor cortex
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What sends online signals to the upper motorneurones?
The cerebellum and basal ganglia
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How are highly rhythmic sequences carried out in low level parts of the motor system?
There's local circuits with central pattern generators contolling coordinated movement and timeg. Lower motorneurones can directly innervate skeletal muscles
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How do upper motorneurones create goal directed voluntary movements?
The cerebellum and basal ganiglia make online corrections to the cerebral cortex and brainstem so top down control results in controlled movement
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What does the primary motor cortex contain? and what does this mean?
A topographical map but not a map of individual muscles, rather a map of motor actions. So activation of M1 does not cause movement directly. In fact activity comes before movement initiation so it is used for motor planning
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What do upper motor neurones specify?
What to do and how to do it
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Primary motor cortex is thought to encode intention but where does motor planning actually begin?
Potentially in the premotor cortex because this encodes abstract information
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What does the superior colliculus contain?
A topographic map of the eye
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What do neurones in primary motor cortex and superior colliculus use?
Population coding to plan movements
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What is the source of planning and intentional awareness?
Premotor cortex, as shown by ERP scalp recordings of readiness potentials. Intention to move comes before conscious intention,
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Premotor cortex operates in a graded manner as shown by movement judgement in glass pattern studies. What does premotor preparation link?
sensory information to intention to move
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What is the cerebellum for?
Sensory-motor coordination
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Where does the cerebellum get input from?
Inferior olive, spinal cord and vestibular nucleus
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What is cerebellar output for?
Precise motor control
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What does the cerebellar do?
Computes the net error between ongoing motor commands and actual movements to correct ongoing errors. This makes it particularly important for initial motor learning where there are lots of errors
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What happens when the cerebellum is damaged?
There are problems at the end points of making movements- intention tremors and accurace errors
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What disorders are related to cerebellum damage?
Truncular ataxia and appendicular ataxia
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What is the basal ganglia for?
Movement initiation. It operates as a gating mechanism to inhibit movements until the appropriate time so movement can be controlled. It is involved in subjective experience of time.
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What structures make up the basal ganglia?
Caudate nucleus and putamen which form the striatum and globus pallidus
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What happens when the basal ganglia is damaged?
Not enough inhibition so get unwanted saccades and movements and lack of control means difficulty starting movements
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What happens when there is unilateral substantia nigra damage?
Hemiballismus (unwanted movements on one side of body)
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What 2 disorders are particulaly associated with basal ganglia damage?
Huntington's and parkinson's
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What do motor maps in M1 project to?
lower motorneurones (local circuits)
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What evidence do e have that local circuits operate by top-down control?
Frontal eye fields: show the cortex controls the brainstem which controls eye movements
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Where does the basal ganglia send input to and what happens next?
The thalamus which feeds back to the motor cortex and this sends input to upper motorneurons which signal to lower motorneurons which inervate skeletal muscles
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To turn movements on the cortex sends excitatory signals to the striatum snt the stiratum sends a lot of inhibitory signals to the substantia nigra which means the substantia nigra is more inhibited than normal. What happens next?
The basal ganglia sends less inbitory signals to the thalamus because it is less activated so the thalamus is able to send more excitatory signals to the cortex which activates the motorneurones and this activates the muscles
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To turn movements off the cotrex sends excitatory signals to the striatum which sends just a few inhibitory signals to the substantia nigra so the substantia nigra becomes less inhibited. What happens next?
The GPi is more excited than notmal so more inhibitory signals are sent to the thalamus meaning the thalamus sends less excitatory signals down eventually to the muscles
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What receptors does the direct pathway (turning movement on) use?
D1 receptors which are excited by dopamine
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What receptors does the indirect pathway (turning movement off) use?
D2 receptors which are inhibited by dopamine
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What can local circuits coordinate?
Multiple muscles simultaneously
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What do monkey lesion studies show about eye movements are controlled by local circuits?
When the superior colliculus is lesioned monkeys are biased to gaze away from a target
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What are neurons in the posterior parietal cortex sensitive to?
Reward values
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What are neurons in frontal and supplementary eye fields tuned to?
Value of eye movements
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What is the supplementary motor area tuned to?
Value of motor movements so the motor system is biased
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How does the premotor cortex select goals for action?
It guides behaviour
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How do we know that the premotor, M1, dorsolateral PFC, parietal cortex and supplementary motor area are all for movement intentions?
There is activity in these areas before movement begins and when cues are removed
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What is anasognosia?
An unawareness of the ability to move
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What is parkinsons cause by?
Damage to the substantia nigra in basal ganglia meaning less dopamine than normal is produced
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What are the symptoms of parkinsons?
Facial masking, resting tremor, freezing, jerky movements, repetitive shaking and slow movements
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What causes huntingtons?
Atrophy of the caudate nuceus in substantia nigra
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What are the symptoms of huntington's?
Unable to do inhiibition so get unwanted movements and eventually get psychotic thoughts
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Where is dopamine made?
Substantia nigra and VTA
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What is the supplementary motor area used for?
Production of learned movements because it's able to generate movements in the absence of any cues
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What does the SMA encode?
abstract motor intention signals to guide internal sequences of movement. It is not encoding individual movements or individual types of movement.
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What happens when SMA is damaged?
Unable to make movements from memory
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What is apraxia?
loss of sensory-motor coordination
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Those with apraxia are unable to plan and carry out movements...what brain areas are damaged and how?
arietal cortex or premotor cortex (causes largely unknown) due to stroke, alzheimers or parkinson's
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There are 3 types of apraxia: ideomotor, ideational and verbal. Ideomotor is a loss of learned, volutary actions, what is ideational apraxia?
an inability to use tools in their proper sequence
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What happens when there's damage to the multisynaptic extrapyrammidial pathway?
People become unable to spontaneously move their face
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Where does the facial nerve start?
It's a lower motorneuron starting in the nucleus of the pons
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What is a feature of the cranial nerve?
It is unilateral and innervates individual muscles
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What is bell's palsy?
Inflammation of the facial nerve
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What happens when the upper motorneuron relating to facial nerves is damaged?
There is loss of voluntary control of specific facial muscles
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The stretch reflex responds to what?
An increase in the length of a muscle
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Recent neuroimaging studies show the basal ganglia are stronly involved in what?
Learning new motor sequences
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What is an important function of the basal ganglia?
Influencing cognition using cognitive pattern generators
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Activation of the cerebellum is strongest when?
During the early stages of learning a new skill
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What is the premotor cortex involved in?
Making sequences of movements
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What circuit are the basal ganglia part of?
A feedback circuit involving all of cortex and the thalamus
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What does the cerebellum work to do?
Provide an error signal between intent and action
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What does the size of a motor cortical area depend on?
The amount of practice a skilled movement is involved in
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What are the main functions of the basal ganglia?
Gating motor acts, processing limic info and using a cognitive pattern generator to influence cognition
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Why do SMAs encode reward values?
To ensure motor systems produce movements which obtain rewards and avoid punishments
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SMA is for...
uncued movements so sequences can be obtained from memory. This comes about because SMA encodes abstract motor intention signals for internally guided movements
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Premotor cortex is for...
Cued movement
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What do dopaminergic drugs have the potential to to?
speed up or slow down the experience of time
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What is the parietal cortex for and what happens when it's damaged?
For sensory motor coordination so damage leads to optic ataxia
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Cerebellum is responsible for online correctionns, what movement does this control?
Smotth, skilled movements
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Where does cerebellum send error signals to?
Dentate nucleus which inputs to frontal cortex and parietal cortex which send info back to the thalamus
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What happens when cerebellum is damaged?
Cerebellar ataxia which is evident when trying to touch nose. Also impediment in learning new skills
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When is the default mode network of behaviour normal?
In young children and organisms with samll/no PFC because executive control systems haven't developed
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What does it mean to use the default mode network?
No task switching an no inhibition of automatic processing
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What can you do with behavioural rules?
initiation, shifting, inhibiting and relating
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What is monitoring an example of?
Contextual control
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What 2 jobs does working memory have?
Maintenance and manipulation
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Posterior part of PFC does simple processing, motor processing, processes current goals. What does anterior PFC do?
Abstract processing and planning long term goals
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What is the standard deviation for IQ?
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What can you predict IQ from looking at fMRI?
Relative activation of frontl and parietal cortices during reasoning tasks
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When is there most rapid increase in cortical thickness?
During adolescence so most able to learn during this time
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What is inductive reasoning?
Using probabilities to form new hypothesise. This has high syntactic and linguistic demands
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What is deductive reasoning?
Association formation and inferencing
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What do deductive and inductive reasoning both use?
left lateral PFC
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Working memory is where information is maintained over time for the achievement of short term goals and where irrelevant information is inhibited, what processes are involved in this?
Deciding between behaviours, reasoning and planning and inhibiting irrelevant and inappropriate acts
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What is the delay period of activation?
The time between initail activation of working memory and the use of information in behaviour
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What does neural activity involved in working memory depend on?
Whether a stimulus has a preferred value
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What brain areas are involved in working memory?
dorsolateral PFC, parietal cortex and basal ganglia
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What do rule selective populations store?
Rules in distributed way in the PFC
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What does the PFC have a feedback loop with?
Basal ganglia which responds to the introduction of new rules for specific stimuli
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How do we know the dorsolateral PFC is involved in inhibiting actions?
Oddball and go-no go tasks show ERP response after 300ms since stimulus onset which triggers the inhibition of an automatic response
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What brain area is involved in inhibiting socially inappropriate behaviours?
Ventral PFC
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Task switching is tested using Winsconsin card sorting task, which brain areas are involved?
Medial PFC, temporal lobe and orbitofrontal cortex (for rewards)
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Ability to relate rules is tested using Raven's progressive matrix and tower of london, which brain regions are involved?
Fronto-polar cortex
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What are the 3 main roles of the PFC?
Control, simulation and inhibition
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The inferior temporal cortex feeds into the secondary sensory cortex, what happens next?
Input to thalamus, parietal cortex and amygdala which feeds into PFC and this feedsback to inferior temporal cortex and feedsforward to the basal ganglia
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Motor response processing happens in posterior PFC, where does strategy processing happen?
Anterior PFC
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What is frontal dysexecutive syndrome?
Where PFC is damaged leading to inability to plan and loss of affect
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What is abulia?
Slowness of movement and inability to repeat back something that is untrue
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What is frontal disinhibition syndrome?
Where working memory is unimpaired but PFC damage leads to inappropriate behaviors and can lead to impulsivity, particularly if it becomes acquired sociopathy
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What is environmental dependency syndrome?
Where PFC damage leads to overreliance on external cues to guide behviours that are inapproriate without awareness of errors
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What happens when there's perseveration?
One of hallmarks of PFC damage. No task switching
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What did lesions by Ferrier and Bianachi find?
Lesioned PFC, found failure in guidance of behaviour
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What processes are involved in conflict monitoring?
Maintain attention, attend to sensory info, identify stimuli requiring more resources
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What brain area did Posner and Peterson find was important for conflict monitoring when they tested this using stroop?
Dorsomedial PFC (which includes the anterior cingulate). The dorsal part is for executive processing, while the ventral part is for affective processing
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Some people say conflict monitoring starts earlier than the anterior cingulate. If this is the case, what is the anterior cingulate for?
For reward learning because it monitors mismatches between expectancies and incoming information. This means its not for detecting errors but instead for detecting mistakes
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When is there greatest activity in the anterior cingulate?
Not when you make a mistake but when you choose not to guess, so you inhibit yourself from making a mistake
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The posterior parital cortex seems to be involved in the allocation of attention, how do we know this?
It is kore active whien we maintain a set of possible actions in thought
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Why is the posterior parietal cortex involved in executive control?
It plays a role in value judgements of possible actions
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How do we know the anterior cingulate ins't involved in exeutive control?
It isn't activated during stroop task
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How do we know the anterior cingulate is involved in motivation?
It is active during conflict tasks so it seems to trigger the brain to engage/disengage control processes
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What does the existence of massive connections between PFC and cerebrocerebellum via the pontine nucleus show?
The cerebellum probably plays a role in cognitive functioning
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Give some examples of executive control processes
Initiation of behaviour, inhibition of behaviour and task switching
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Abulia is...?
A fundamental loss of interest in the world
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Give some inhibitory functions of executive control?
Suppression of socially-inappropriate behviours, removal of irrelevant information from working memory, prevention of irrerlavant info from interferring with other processes and restraint of potentiated behaiours
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What is required for simulating behavioural consequences?
Abstraction and planning
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Why is the parietal association cortex critical in the allocation of attention?
Because it plays a role in value judgements of possible actions as part of executive function
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How might the cerebellum update error signals for future tasks?
Through prominent cennections with the PFC...the cerebellar's ability to do fast, error signalling may have been co-opted for cognitive tasks over the course of evolution
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What are the 2 main features of environmental dependence syndrome?
Imitation and utilization
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Frontal dysexecutive syndrome happens when the lateral PFC is damaged..what are the main symptoms?
Lack insight, unable to initiate or plan, confabulate and abulia
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Frontal disinhibition syndrome comes about through damage to the ventral/medial PFC, what distinguishes it from other PFC disorders?
Constant movement and inappropriate, fail to integrate reward values so no regret on IOWA gampling task
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What region of PFC should be damaged to get apathy?
Lateral PFC
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What have odd ball and no-go tasks shown?
Dorsolateral PFC and basal ganglia involved in behaviour inhibition
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When might you be unable to integrate images to make a coherent narrative?
When PFC is damaged
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Which area of PFC is necessary for integrating information?
fronto-polar PFC. This are creates higher-order rules for understanding and for planning future behaviours, particularly for behavious requiring integration of exploratory goals
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Does dopamine signal a reward by itself?
No, it signals the motivation to pursue a reward
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What is normative decision making?
Using probabilities which biases the value of an outcome
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What is descriptive decision making?
Making estimation of rewards and losses. Can be called prospect decision making
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What is bounded rationality?
Where there is limited access to probabilities
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What is game theory?
Using probabilities, expected utility and perspective taking to make a ayoff matrix
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What do you need for game theory?
An index of reward-prediction error
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What is expected utility?
Utility is a psychological value. You weigh up anticipated outcomes with a current state to make a decision. In this way expected utility is reference dependent
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When are people risk averse?
When low probabilities (losses) are overestimated
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When are people risk seeking?
When high probabilities (losses) are underestimated
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What do gamblers find rewarding?
Near misses because VTA increases when a reward is unpredictable meaning more dopamine is released when rewards are random
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Why are parkinson's sufferers at risk of becoming pathological gamblers?
Drugs cause neural changes in limbic system
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What neural mechanisms might be involved in delay dscounting?
Might be different populations when reward is immediate compared to when it is delayed
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Why do we not know if dopamine is just for rewards?
Studies only focus on rewards, don't study negative outcomes
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What happens when the reward value of a stimulus is encoded?
This is translated into abstract signals allowing rewards to be compared and this controls behaviour
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What is central PFC responsible for?
Feeling of regret because feedsback about negative outcomes. Activity here decreases when reward is achieved but decreases even more when reward is expected and not achieved
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How is neuromarketing used to optimize products?
Study decision values of small groups and create algorithms which are used to predict consumer choices which willthen assess preferences
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Habits form due to repeated reinforcement. What are their defining features?
Slow to learn but resistant to change
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Which brain areas are involved in associating stimuli with rewards to form habits?
Basal ganglia and ventral stiatum
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Which areas are involved in choosing the motor action of a habit?
Basal ganglia and dorsal striatum
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Which brain area learns new heuristics?
dorsomedial PFC
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What 3 heuristics are there?
familiarity, satisficing and anchoring
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Which area encodes reward value of actions by becoming more active for larger or more probable rewards?
lateral intraparietal area
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Dopamine projects to the meocortical and mesolimbic system. The mesocortical system mainly involves the medial PFC, what is included in the mesolimbic system?
nucleus acumbens, amygdala and hippocampus
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What are social rewards more important than?
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What do you need for altruism?
Internal reward signal and social cognition
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Which brain area gives internal reward signals?
Ventral striatum
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Which brain regions are necessary for social cognition?
Lateral parietal area and medial frontal cortex
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Why is cooperation rewarding?
Because it shows an increase in trust
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To cooperate you first need to evaluate other's decisions, this used the cingulate gyrus. You then need to anticpate cooperation, what brain region does this and what happens if cooperation is succeeded?
Dorsal striatum anticipates cooperation and nucleus accumbens responds to reward of trust
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As well as producing reward signals, the ventral striatum does something else regarding altruism, what is this?
Becomes more active when more punishment for something social
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There might be a dual system with the insular cortex and dorsolateral PFC. What do these areas do?
Insular cortex perceives injustice and dorsolateral PFC for self control
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Where have mirror neurons been found?
Premotor cortex, parietal cortex, inferior frontal cortex
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False belief tasks are passed by 4 years. Which brain areas must be mature enough for this to happen?
Medial frontal lobes and temporal lobes which do perspective taking (ToM, mirror neurons here)
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What did Blaise Pascal do?
Suggested the concept of probability can be used as a means to evaluate likelihoods
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Expected utility would be...
Considering a potential monetary gai in the context of one's current financial situation
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How do descriptive theories empirically account for human biases?
Probabilities are weigted because additional factors are taken into account to estimate rewards and losses
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What did Nash do?
Formulate the concept of game theory for the study of decision making to enable exploration of scenarios in which multiple people are making decisions
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How does VTA affect cortical functioning?
Via the mesocortical pathway
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What do secondary reinforcers give?
Indirect benefits
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What will activity of VTA transfer?
Value of an unconditioned reinforcer to a conditioned stimulus which predicts the reinforcer
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What is temporal difference learning?
Where successive environmental states and their predictions are correlated over time. This is what VTA uses to guide behaviour because it is this area that provides an index of the reward prediction error
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What are salient events?
Those that will provide information that is important for future behaviour. Ventral striatum likely to respond more to these than simply rewards
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Card 2


Action potentialls starting in he spinal cord/brainstem reach the neuromuscular junction, what happens here?


Acetylcholine is released from motor neurons and binds to receptors at the end plate of the muscle fibres. Action potentials are then made in the muscle surface membrane.

Card 3


What happens when action potentials are made in a muscle's surface membrane?


Preview of the front of card 3

Card 4


What happens when acetylcholine is released from motorneurones at the neuromuscular junction but there are abnormal muscle proteins?


Preview of the front of card 4

Card 5


What happens when acetylcholine transmits a signal at the neuromuscular junction but there are abnormal receptors to meet them?


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