- Created by: OliviaAnneSumner
- Created on: 05-11-17 08:37
Cortex of both hemispheres subdivided into 4 lobes:
*Frontal Lobe (back)- motor area, deals with movement in opposite side of body.
*Parietal Lobe (front)- somatosensory area, separated from motor area by central sulcus. Sensory info from skin.
*Occipital Lobe- visual area, visual info. Right VF- left V.Cortex.
*Temporal Lobe- auditory area. speech-based info.
Broca's Area (left frontal lobe)- speech production, damage- aphasia, slow speech, lacks fluency, understand spoken language, thoughts in writing, talk in short meaningful sentences.
Broca studied 9 patients, similar language problems and lesions in left frontal hemisphere, patients with same problem in right hemisphere didn't have same language problems.
Wernicke's area (left temporal lobe)- understanding language, damage- aphasia, produce neologisms as part of speech, language comprehension.
Left: language, speech, logic, Broca/Wernicke's areas, sequencing, hearing, maths, analysis, facts.
Right: visual motor tasks, hearing, artistic capabilities, imagination, rhythm, feelings, tunes, visualisation, intuition, recognition.
*Hemispheres connected by corpus callosum, info recieved from one hemisphere, sent to other.
*Right VF- Left Hemisphere- Right hand.
Rational of Split Brain Research
*Investigate different abilities of 2 hemispheres, treatment for severe epilepsy- surgeons cut through corpus callosum.
*Aimed to prevent violent electrical activity accompanies epileptic seizures crossing from one hemisphere to another- split brain patients.
Split Brain Research
Sperry- capabilities of separated hemispheres, severed corpus callosum. Able to send visual info to one hemisphere at a time.
*Describe what you see: pic of obj shown to R.V.F, easily describe what was seen. When shown to L.V.F. couldn't describe it, reported nothing there, couldn't access language centres.
*Regognition by touch: couldn't attach verbal labels to objects attached to L.V.F. could select matching object from grab-bag with right hand. Objs hidden behind screen, left hand able to select closley associated obj presented to LVF, couldn't verbalise selection.
*Composite words: 2 words presented at once on each side of VF, patient rightly say R.V.F. obj, draw L.V.F. item using left hand.
*Matching faces: picture processed by right hemisphere constantly selected, left picture ignored. Composite picture presented, R.V.F. dominated when verbally describing, L.V.F dominated in selecting/matching photo.
*Differences between hemispheres, connectivity between regions is as important as opperation of different parts.
*Brain's tendency to change/adapt functionally and physically due to experience/new learning (corticial remapping)- change in synaptic functions.
*Infancy- rapid growth in synaptic connections (15,000 for each neuron by 2-3 from 2,500 at birth).
*Halved in adult brain, rarley used connections deleted, frequently used connections strengthened- cognitive pruning.
*Brain in continual state of change from growth in early years, change/refine in adulthood.
*Divided into 2 symmetrical halves. Physical/psychological functions dominated by hemisphere (lateralisation).
*Activity on Right hand side controlled by left hemisphere.
*Sensory systems send messages to/from hemispheres.
*Outer layer- cerebral cortex. Covers inner parts of brain- grey, location of cell bodes. Divided into 4 lobes with different functions.
*Corpus Colosseum connects hemispheres, info transfered across hemispheres.
Localisation vs Holistic Theory
*Localisation: different parts of brain- different tasks. Certain area damaged, function associated with area effected.
*Wernicke's Area- understand speech, form comprehensive sentences.
*Broca's Area- thoughts--speech.
*Broca/Wernicke localisation of function, different parts of brain- different tasks- different body parts.
*Before Broca/Wernicke's areas disocvered, scientists took holistic view, all parts of brain involved in processing of thought/action.
*Central Core- hypothalamus, body temp, involuntary behaviours.
*Limbic System- amygdala, control emotions, memory.
*Cerebrum- intellegence, cerebral cortex.
*Neurons commincate within neural networks, separated by synapse. Signals chemically transmitted across, when electrical impulse reaches presynaptic terminal- triggers release of neurotransmitter from synaptic cleft.
*Neurotransmitter- chemical, diffuse across synapse to next neuron. Taken up by complimentary post-synaptic receptor site. Chemicall message converted back into electrical impulse. Each have own molecular structure, specialist functions.
*Neuron at resting state- internal - charge. Activated by stimulus, internal + charge, causes action potential. Electric impulse travels down axon to presynaptic terminal.
*Impulse may be chemically transmitted across synaptic cleft- synaptic vesicle fuses with axon membrane. Triggers release of neurotransmitters (chemicals diffuse across synapse to next neuron carrying chemical message) from synaptic vesicles (fuse with axon membrane).
Structure of Neuron
Soma- cell body, nucleus, dendrites protrude from cell body, carry nerve impulses from neighbouring neurons towards soma.
Axon- carries impulses away from soma down length of neuron. Covered in fatty layer, Myelin sheath, protect axon from/speeds up electrical transmission of impulse.
Myelin Sheath- if continuous, slow down impulse. Segmented by Nodes of Ranvier, speed up transmission of impulse, force it to jump along gaps along axon.
Synapse- terminal buttons, communicate with next neuron in chain.
Transmit signals electrically/chemically.
Motor- connect CNS to muscles/glands. When stimulated, release neurotransmitters- trigger muscle movement.
Sensory- info from PNS-CNS. Convert info from sensory receptors into neural impulses, impulses go to brain, translated into sensations.
Relay- brain of CNS. connects sensory and motor neurons.
Fight or Flight
ANS- parasympathetic state- sympathetic state.
Amygdala- triggered by threat, distress signal sent to hypothalamus.
Hypothalamus- SNS communicates with body, stimulates pituitary gland to release ACTH.
Sympathetic Nervous System- prepare body for rapid action.
Adrenal Medulla- recieve SNS signal, release adrenaline.
Adrenaline- divert blood from skin/kidneys/digestive system // increase breathing/heart rate and blood pressure // causes blood sugar/glucose to be released into blood stream- energy.
Glands and Hormones
Works alongside NS, control vital functions, slower- widespread/powerful effects.
Hormones secreted into bloodstream, effect cells with receptor for hormone- several organs effected, diverse responses.
*Pituitary Gland- controls all endocrine glands, influences growth, metabolism, regeneration.
*Hypothalamus- regulate hunger, thirst, sleep, wakefulness, body temp.
*Adrenal Glands- secrete adrenaline, regulate metabolic processes, water balance, blood pressure.
*Ovaries- produce insulin and progesterone.
*Pancreas- aid digestion, produce insulin.
*Thyroid- regulate energy/metabolism.
Specialised network of cells, primary internal communication system.
Collects/processes/responds to environmental info.
Co-ordinates working of organs.
Split into 2: Central / Peripheral.
Central Nervous System
*Centre, passes message to rest of body.
*Brain- centre of conscious awareness, cerebral cortex divided into 2 hemispheres.
*Spinal Chord- extension of brain, reflex actions.
Peripheral Nervous System
Transmits messages via neurons to/from CNS.
*Autonomic N.S.- govern vital body functions (breathing). Subdivided- sympathetic NS (flght/flight), parasympathetic (slow down).
*Somatic N.S.- control muscle movement, recieves information from sensory receptors.
*Following physical injury/trauma unaffected areas adapt/compensate for damaged areas, example of neural plasticity.
*Neuroscientists- happen quickly after trauma (spontaneous recovery), slows down after several weeks/months, therapy may be needed for progress to continue.
*Brain rewire/reorganise, form new synaptic connections close to damaged area. Secondary neural pathways unmasked, enable functioning to continue.
*Axonal Sprouting new nerve endings grow, connect to undamaged areas, form new neural pathways.
*Reformation of blood vessles, fix itself.
*Recruitment of Homologous Areas on opposite hemisphere to do specific tasks, blockage remains.
Factors Effecting Functional Recovery
Age: reduces with age. Huttenlocher- only option following brain trauma beyond childhood= develop compensatory behavioural strategies work around deficit (social support/strategies to deal with cognitive deficit).
Abilities thought to be fixed in childhood modified in adults with intense retaining, Elbert et al- capacity for neural reorganisation much greater in children- extended practice adults require to produce changes.
Educational Attainment: Schneider et al- patients with college education 7x more likley to be disability free a year after brain trauma. Retrospective study, 769 studied. 214 achieved DFR after 1 year, 39.2% with 16+ years of education and 9.7% less than 12 years of education.
Cognitive reserve factor in neural adaptation following traumatic brain injury. Spontaneous recovery slows down after a while, rehab neccessery although brain has ability to heal itself to a point, requires further intervention to be fully successful.
Move from state of alertness-fatigue every 90 minutes. Human mind can focus for 90 minutes until body runs out of resources, lose concentration become fatigued, hungry.
*Ecidence is anecdotal, lacks scientific rigour. Can't conclude rhythm is present from evidence.
Ericsson: Studied prodigious violinists. Best performers practice for 3 sessions during day lasting less than 90 minutes, break between sessions to recharge. Indicates ultradian rhythm exists in these individuals.
A-typical participants, may not be true for everyone. Shorter brac- can't be generalised.
*Span 90 minute cycle. Brain wave activity monitored by EEG.
*Stage 1/2: Light, easily woken. Rhythmic brain wave patterns- slower. Stage 1- alpha wave, slows down as sleep deepens to theta wave by stage 2. Experience hypnic jerks/hypogogic hallucinations.
*Stage 3/4: Delta waves, slower, greater amplitude. Deep slow wave sleep, hard to wake.
REM (Paradoxical) SLEEP
*Stage 5: Body paralysed, brain activity resembles awake person. Rapid eye movement, dreaming, increased heart rate, rapid shallow breathing.
Sleep Stages A03
Dement and Kleitman- Sleep patterns of 9 adults in sleep lab recorded via EEG, controlled caffeine/alcohol consumption. REM highly correlated- dreaming. More vivid=more active, waking in REM- could clearly recall dreams.
+Results replicated, reliable.
+Extraneous variables controlled, high int. validity.
+Controlled lab- standardised procedures.
+Stages 1/2 distinct via different EEG waves, objective measurement.
-Small sample size, generalise?
-Artificial setting- ecological validity.
-Individual differences (age), Tucker et al- biologically determined, differences weren't driven by circumstance.
-Childhood/elderly sleep not studied, unrepresentitve. Relies on inferences, uncertain dreaming only occurs in REM.
Depressive disorder, seasonal pattern of onset.
Circannual rhythm, subject to yearly cycle.
Emotional characteristics- low self-esteem, hopelessness, worthlessness.
Behavioural characteristics- lack of sleep, low sex drive, change in appetite.
Eastman- 96 participants, 1 / 3 light treatments: hour and a half in AM/PM/Placebo. After 3 weeks:
*AM significantly more remissed, not due to chance.
*PM more remised than placebo, not significant. More than 10.
*Placebo 30% ''seemed'' to improve, over 10 participants- phototherapy may not be effective.
-Matched pairs design, all SAD.
*Function- ovulate. Time between shedding of womb lining to day before next period (28 days).
*Hormones stimulate folicle in 1 ovary to ripen ovum/release oestrogen.
*Ripe ovum- follicle to release progesterone, womb prepares for pregnancy, increases blood supply.
*2 weeks after ovulation, no pregnancy- progesterone reduced, lining shed, ovum absorbed into body.
*Endogenous system- influenced by exogenous factors- cycle of other women (pheromones).
Knowledge derived from animal studies. Sea urchins release hormones into surrounding water, others in colony eject sex cells simultaneously. Effects on human behaviour (pheromones)- inconclusive. Extrapolated? Lacks reliable consistant findings.
McClintok- 29 women with irregular periods, pheromone samples gathered from 9 at different cycle stages via. underarm cotton pad worn for 8 hours, treated with alcohol, frozen. Rubbed on upper lip of participants.
+68% changes to cycle, brought closer to cycle of odour donor, menstration influenced by exogenous pacemakers.
-Small sample size, generalise?
-Weak support, not significant.
-Numerous uncontrolled variables- stress, diet, exercise.
-Synced births- range of women treated at once, complications- take care of baby with deceased mother.
Siffre (Circadian Rhythms)
*Deprived himself of natrual light/soundm 2 months in cave. Resurfaced mid-september, thought it was mid-august. Repeated 10 years later, similar results.
*Free-running circadian rhythm settled down to 25hrs. Continuted to fall asleep/wake at regular schedual.
-Case study, idiographical, unrepresentitive, can't be generalised.
-Confounding variable- artificial light.
+Replicable reliable results.
+Remove exogenous, endogenous able to regulate despite slight alterations.
+Economy- understand shift work, productivity and saftey. Workers aren't vulnerable as consequence of disruption of circadian rhythm. Chenobyll- 2am-4am.
Aschoff and Wever (Circadian Rhythms)
*Group spent 4 weeks in bunker, deprived of natrual light.
*All but one circadian rhythm 24-25hrs, one sleep-wake cycle extended 29hrs.
+Group, sample more representitive although still small.
+Endogenous able to regulate SW cycle despite alteration due to change in exogenous.
-C.V.- artificial light entrain biological rhythms.
-Individual differences- age/sleeping habbits.
Folkard et al (Circadian Rhythms)
*Group of 12, dark cave- 3 weeks. Retired to bed when clock said 11.45pm, rose at 7.45am. Gradually increased speed of clock, unknown to participants, reduced to 22hr day.
*No participants able to adjust to new regime.
+Endogenous pacemakers persist in absence of exogenous despite changes.
+Economy- peak times when drugs most effective, less drugs used- more economical, user reaps- maximum benefits.
Superchiasmatic Nucleus- *Small bundle of nerve cells, hypothalamus in each hemisphere- one severed, other able to take over [plasticity].
*Primary endogenous pacemaker in humans, influential- maintain circadian rhythms.
*Nerve fibres connected to eye cross in optic chasm, SCN gets info about light from here, sends into to pineal gland, allows biological clock to adjust to changing daylight patterns.
Pineal Gland- *SCN passes info on daylight/length to PG, increases melotonin production in evening.
*High melotonin- low light levels.
Environmental, reset biological clock- entrainment.
Absence of external cues- free running bio clock, ticks in cyclic patter, doesn't necessarily match 24 hours society.
Social Factors- new born baby with random SW cycle, fully trained after 16 weeks. Entrainment- schedules imposed on baby by parents, individual differences.
Light- key zeitgeber, reset SCN, important in maintaining SW cycle.
Campbell and Murphy
*15 participants woken at various times, light pad shone on back of knees- deviation in usual sleep/wake cycle of upto 3 hours.
+Artificial light can be used for entrainment.
-Not replicated, reliable?
-Woke due to different zeitgeber- artificial light.
-Participants unknown age.
-Small sample size.
Miles Et Al
*Recount story of man blind from birth, circadian rhythm of 24.9hrs. SW cycle couldn't be adjusted despite social cues, take sedatives at night/stimulants in morning to keep pace with 24hr society.
+Natrual light key exogenous zeitgeber.
+SCN primary endogenous pacemaker- use of stimulants.
-Case study- idiographic, not experimental, unscientific- not proven.
Steel Et Al
*6 participants, isolation in Arctic. Monitored for 6 weeks, lived in constant daylight, kept sleep log. 5/6 deceloped free running SW cycle more than 24hrs.
*Sleep patterns individual, none became synchronised.
-Individual differences- can't be generalised.
Decoursey Et Al
*Destroyed SCN in 30 chipmunks, returned to natrual habitat, observed for 80 days. SW cycle disappeared, many died- awake/vulnerable to predator attack when should have been asleep.
*Importance of SCN.
*Animal ethics- was harm worth it?
Ralph Et Al
*Bred mutant hamsters, 20hr SW cycle. Transfered cells/SCNs from normal hamsters. Began to follow 24hr cycle within 6/7 days, rhythm no longer matched genes.
+Importance of SCN over exogenous/endogenous factors.
Stephan and Zucker
*Rats- 12hrs of light followed by 12hrs of dark. Circadian rhythm of drinking/loco-motor activity.
*Rats drank/more active in darkness, compared to control group with damage to SCN.
*Damage to SCN in 11/25 surviving rats eliminated normal circadian patterns.
+Importance of SCN.
*Measure changes in brain activity during task- blood flow in area- increased neural activity. Uses radiowaves/magnetic field- most active neurons require most energy.
*Oxygen carried in Hb, deoxygenated Hb- different magnetic quality.
*Creates 3D dynamic maps, shows info on blood flow/which part of brain is active in activity- localisation.
+Moving picture, activity one second after it occurs.
+No radioactive tracer, risk free/non-invasive.
+High spatial res (accurate to 1-2mm), clear localised functions.
-High cost, small sample size- generalise?
-Machines expensive to buy/maintain, highly trained workers required- hard to organise.
-Indirect, studies blood flow not firing of neurons.
-Low temporal res, 1-4 seconds.
Electrodes on scapl, charge detected- response to stimulus. Activity level mapped over time. Can track sleep stages.
*Info processed as electrical activity (action potential), nerve impulses measured. Can detect epilepsy/Alzheimer's.
*Alpha, Beta, Theta, Delta waves.
Desynchronised- undetected, combo of waves.
+High temporal res- 1-10ms.
+Cheaper, more widley available.
-Spatial res low, superficial regions- can't pinpoint exact region- inconclusive.
-Experts required to interpret data, subject to human error?
-Can't explain what is occuring in deeper brain regions, hypothalamus.
Electroded attached to scalp, stimulus presented multiple times- look for activity related to it.
''averaging'' graphed, reduces extraneous activity.
*Latency- time between presentation of stimulus and response.
*Sensory EEP- before 100secs.
*Cognitive EEP- after 100secs.
*Averages out brain activity, location of function clearer.
+More specific than raw EEG reading.
+High temp. res (1-10ms) derived from EEG.
-Many trials needed to get meaningful data, small- hard to pick out from other electrical activity.
-Restricted to neocortex, deep brain activity isn't recorded.
-Differing procedures adopted, not standardised, hard to replicate.
-Low spatial res., superficial general regions.
*Underlying neurobiology of behaviour, study interesting behaviour while alive, examine brain for abnormalities after death.
*Broca- Tan, speech problems caused by lesion in Broca's area.
Post Mortem A03
+Human brain abnormalities directly studies, not on animals.
+Examine deeper regions of brain, hypothalamus.
+Harrison- post mortem central in studying Schizophrenia, see strucutral abnormalities/changes to neurotransmitter system.
-Lack validity- small sample size, requires special permission.
-Deficit in lifetime may not be linked to deficit in brain.
-Informed consent- lose ability to consent in lifetime- consent quickly needed from relatives.
-Retrospective approach- can't follow up on anything which arises.