biopsychology Flashcards
Structure + Function of Sensory, Relay + Motor Neurons: neurones (A01)
100 billion neurones in human nervous system 80% of which are located in brain- transmitting signals electrically + chemically these neurones provide nervous system w/primary means of communication
Neurones vary in size from less than millimetre to up to metre long depending on their function but all share same basic structure
Structure + Function of Sensory, Relay + Motor Neurones: myelin sheath (A01)
If myelin sheath was continuous this would have reverse effect + slow down electrical impulse- myelin sheath is segmented by gaps called nodes of Ranvier
speeds up transmission of impulse by forcing it to ‘jump’ across gaps along axon
Structure + Function of Sensory, Relay + Motor Neurones: synapse (A01)
end of axon are terminal buttons that communicate w/next neurone in chain across gap
Structure + Function of Sensory, Relay + Motor Neurones: nucleus + dendrites (A01)
cell body includes nucleus which contains genetic material of cell Branch-like structures called dendrites protrude from cell body receive signals from other neurones or from sensory receptors
Structure + Function of Sensory, Relay + Motor Neurones: axon (A01)
axon carries impulses away from cell body down length of neurone axon is covered in fatty layer of myelin sheath that protects axon + speeds up electrical transmission of impulse
sensory neurons (unipolar) (A01)
found in receptors such as eyes ears, tongue + skin- carry nerve impulses from PNS to spinal cord + brain (CNS) these nerve impulses reach brain they are translated into ‘sensations’ such as vision, hearing, taste + touch
not all sensory neurones reach brain as some neurones stop at the spinal cord allowing for quick reflex actions- have long dendrites + short axons
relay neurons (multipolar) (A01)
most common type of neurone
only found in brain + spinal cord (CNS)- connect sensory neurones to motor or other relay neurones
have short dendrites + short axons
motor neurons (multipolar) (A01)
neurones carry messages from CNS + control muscle movements
stimulated these neurones release neurotransmitters that bind to receptors on muscle + triggers response which leads to muscle movement
Muscle relaxation is caused by inhibition of motor neurone
have short dendrites + long axons
how neutrons function together (A01)
stimulus is presented
Sensory neurones send message through peripheral nervous system
message reaches spinal cord where it is passed to relay neurone
found throughout CNS
message is then either passed to motor neurone or sent to brain for further processing
motor neurone carries message to an effector such as muscle or gland motor neurone sends messages to muscles located in arm which contract - pulling hand away from candle
synaptic transmission (A01)
Signals w/in neurones are transmitted electrically but signals between neurones are transmitted chemically across synapse
electrical impulse reaches end of the neurone it triggers release of neurotransmitters from tiny sacs -synaptic vesicles
Neurotransmitters are chemicals that diffuse across synapse to next neurone in chain
neurotransmitter crosses gap it is taken up by postsynaptic receptor site – dendrites of next neurone-chemical message is converted back to an electrical impulse + process of transmission begins again in this other neurone effects of this last until neurotransmitters travel back where they came from to be taken up again by presynaptic neurone-‘reuptake’ which allows neurotransmitters to be stored again + made available for later use
neurotransmitters (A01)
Dozens of neurotransmitters have been identified in brain
Each neurotransmitter has its own specific molecular structure that fits perfectly into post-synaptic site like lock + key
Neurotransmitters also have specialist functions eg. dopamine affects nervous system in several ways including emotional arousal, pleasure + voluntary movement
Summation (A01)
neurone can receive both excitatory + inhibitory neurotransmitters at same time
likelihood of cell firing is therefore determined by adding up excitatory + inhibitory synaptic input- summation if net effect on post-synaptic neurone is inhibitory neurone will be less likely to fire
if net effect is excitatory neurone will be more likely to fire
Excitation + inhibition (A01)
Neurotransmitters have either an excitatory or inhibitory effect on neighbouring neurone
serotonin causes inhibition in receiving neurone resulting in neurone becoming more negatively charged + less likely to fire
message is likely to be stopped at post-synaptic neurone inhibitory synapse
dopamine causes excitation of post-synaptic neurone by increasing its positive charge + making it more likely to fire
synapse is more likely to cause post-synaptic neurone to fire- excitatory synapse
excitatory potential is like accelerator + an inhibitory potential is like brake
central nervous system (CNS): brain (A01)
involved in psychological processes + is centre of all conscious awareness
brain’s outer layer cerebral cortex is highly developed in humans + is what distinguishes our higher mental functions from those of animals
brain is divided to 2 hemispheres
central nervous system (CNS): spinal cord (A01)
extension of brain
responsible for reflex actions pulling your hand away from hot plate
responsible for relaying information between brain + rest of body
peripheral nervous system (PNS) (A01)
PNS transmits messages via millions of neurones too + from CNS
nerves outside brain + spinal cord function of PNS is to relay nerve impulses from CNS to rest of body + from body back to CNS
peripheral nervous system (PNS): Somatic nervous system (SNS) (A01)
controls voluntary actions
achieved by receiving info from senses + carrying sensory + motor info to + from CNS
peripheral nervous system (PNS): Automatic nervous system (ANS) (A01)
governs vital functions in body such as breathing, heart rate, digestion, sexual arousal + stress responses
ANS controls involuntary actions eg. breathing, heart rate + digestion via internal organs + glands in body
ANS carries only motor info to + from CNS
Primarily involved in responses that help us deal w/emergencies
Neurones travel to virtually every organ + gland w/in body preparing body for rapid action
eg. sympathetic nervous system causes body to release stored energy pupils to dilate + hair to stand on end
slows down Inhibits less important bodily processes eg. digestion + urination
endocrine system: glands (A01)
Organs in body that produce + secrete hormones to regulate many bodily functions
major endocrine gland is pituitary gland located in brain
called ‘master gland’ bc it controls release of hormones from all other endocrine glands in body
Automatic nervous system (ANS): Parasympathetic nervous system (A01)
Primarily involved in returning to body to rest state once emergency has passed
sympathetic branch causes heart rate to become faster peripheral branch slows heartbeat down
bodily processes that are inhibited by sympathetic branch are returned to normal
Automatic nervous system (ANS): sympathetic nervous system (A01)
involved in responses that prepare body for fight or flight
Impulses travel from SNS to organs in body to help us prepare for action when we are faced w/dangerous situation
endocrine system (A01)
endocrine + nervous system work closely together to regulate various physiological processes in human body
endocrine system works much more slowly than nervous system but has widespread effect
endocrine communicates chemical messages to organs of body messages- hormones regulate body’s growth, metabolism + sexual development + function
Hormones are released from glands in body- major glands of endocrine system are pituitary, pineal, adrenals, reproductive organs + thyroid
pituitary gland- called master gland bc it controls several other hormone glands in your body including thyroid + adrenals, ovaries + testicles
endocrine system: hormones (A01)
Chemicals that circulate in bloodstream + influence target organs in order to regulate bodily activity
produced in large amounts but disappear quickly- effects are very powerful
glands adrenal: adrenaline FUNCTION (A01)
Triggers fight-or-flight response in stressful situation by increasing heart rate, dilating pupils
glands testes: testosterone FUNCTION (A01)
development of testes in womb
surge of testosterone during puberty is also responsible for secondary sexual characteristics eg. facial hair + deepening voice
glands ovaries: oestrogen +
progesterone FUNCTION (A01)
help to regulate menstrual cycle
Oestrogen is involved in repairing + thickening uterus lining whilst progesterone maintains uterine lining
glands pineal: melatonin FUNCTION (A01)
Regulates sleep-wake cycle
High levels of melatonin cause drowsiness when daylight is low
Fight or Flight Response Including Role of Adrenaline (A01)
experience an acute stressor hypothalamus directs sympathetic branch of ANS to send neurotransmitters to adrenal medulla
results in release of adrenaline to bloodstream- release of adrenaline as well as noradrenaline causes “fight or flight” response by triggering several physiological reactions
reactions include an activation of emergency functions such as increased heart rate + blood pressure so that oxygen is pumped to muscles to enable increased physical activity
Non-emergency bodily processes eg. digestion are suppressed here leading to ‘dry mouth’ + changes in stomach activity often associated w/these situations
Fight or Flight Response Including Role of Adrenaline: sympathetic state (A01)
Increases heart rate
Increases breathing rate
Dilates pupils
Inhibits digestion
Inhibits saliva production
Contracts rectum
Fight or Flight Response Including Role of Adrenaline: parasympathetic state (A01)
Decreases heart rate
Decreases breathing rate
Constricts pupils
Stimulates digestion
Stimulates saliva production
Relaxes rectum
Fight or Flight Response: Adrenaline + Noradrenaline (A01)
Increase:
heart rate + blood pressure
glucose release
respiration + perspiration-sweat
blood coagulation
Decrease:
digestion
Fight or Flight Response: may be different in females (A03) (1)
P: fight or flight response may be different in females
E +E: Taylor et al found that females adopt ‘tend + befriend’ response in stressful or dangerous situations Women are more likely to protect their offspring + form alliances with other women rather than fight an adversary or flee
L: suggests that research to fight or flight response is gender bias as biological processes that occur during stress may only apply to males
Localisation of Function in Brain (A01)
specific functions have specific locations w/in brain
certain area of brain is damaged through illness or injury associated function will also be affected
brain is divided into 2 symmetrical halves called left + right hemispheres
outer layer of both these hemispheres is called cerebral cortex
Localisation of Function in Brain: auditory centres (A01)
human brain has 2 primary auditory cortices 1 in each hemisphere
primary auditory cortex in both hemispheres receives info from both ears via 2 pathways that transmit information about what sound is + its location
located in temporal lobe either side of brain
Damage to this area may produce partial hearing loss more extensive damage more extensive loss
Localisation of Function in Brain: motor centres (A01)
Movement is centred on motor cortex of brain which sends messages to muscles via brain stem + spinal cord
motor cortex is responsible for generating voluntary motor movements
located at back of frontal lobe in both hemispheres – motor cortex in each hemisphere controls movement in opposite side of body
Damage to this area may result in loss of control over fine movements
Localisation of Function in Brain: somatosensory centres (A01)
referring to sensation of body
somatosensory cortex lies next to motor cortex in brain
somatosensory area is where sensory information from skin is represented
perceives touch so number of neuronal connections needed dictates amount of somatosensory cortex needed for that area of body
located at front of parietal lobe in both hemispheres
somatosensory cortex on 1 side of brain receives sensory information from opposite side of body
Localisation of Function in Brain: visual centres (A01)
brain has 2 visual cortices 1 in each hemisphere
visual cortex is in occipital lobe which is at back of brain- main visual centre
located in occipital lobe at back of brain-each eye sends info from right visual field to left visual cortex + from left visual field to right visual cortex
means that damage to left hemisphere eg. can produce blindness in part of right visual field of both eyes
specifically an area called Area V1 which seems to be necessary for visual perception
individuals w/damage to that area report no vision of any kind
Localisation of Function in Brain BROCA + WERNICKES AREAS: Language centres (A01)
left hemisphere + that is where most language processing in most of population is situated
Localisation of Function in Brain BROCA AREAS: Language centres (A01)
identified area of brain responsible for speech production
located in small area in left frontal lobe
Damage to Broca’s area causes Broca’s aphasia which is characterised by speech that is slow, laborious + lacking in fluency
Localisation of Function in Brain WERNICKES AREAS: Language centres (A01)
found that patients who had damage in an area close to auditory cortex had specific language impairments
included inability to comprehend language + anomia which is when someone struggles to find word they need
but Wernicke noticed that these people did have fluent speech when they could access words quickly
led Wernicke to suggest that area now called Wernicke’s area was important for understanding language + accessing words
Patients who have Wernicke’s aphasia will often produce nonsense words as part of content of their speech- small area in left temporal lobe
Localisation of Function in Brain: Localisation supported by case study evidence (A03) (1)
P: Localisation supported by case study evidence
E: 1861 man who became known as “Tan” since this was only word he could speak met famous surgeon Paul Broca at hospital in France Shortly after meeting Tan died + Broca performed his autopsy During autopsy Broca found lesion in region of his brain
E: Broca concluded that Tan’s aphasia was caused by damage to this region + that this particular brain area-controlled speech- That region of brain was later renamed Broca’s area in honour of doctor
L: increases validity of theory of localisation as it appears damage to specific brain regions result in specific deficits
Localisation of Function in Brain: supporting evidence from brain scan research (A03) (2)
P: supporting evidence from brain scan research
E + E: Peterson et al used brain scans to demonstrate how Wernicke’s area was active during listening task + Broca’s area was active during reading task Tulving et al have shown that episodic + semantic memories were recalled from different sides of prefrontal cortex whilst procedural memory is associated w/cerebellum
L: positive as there is wide range of evidence to support idea that different areas of brain have different functions
Localisation of Function in Brain: evidence against localisation of function comes from animal research (A03) (3)
P: evidence against localisation of function comes from animal research
E: Lashley removed between 10-50% of cortex in rats that were learning maze + found that no area was more important than any other in terms of their ability to learn maze
E: problem as it suggests that higher cognitive processes eg. learning are not localised but distributed in more holistic way involving entire brain
L: reduces validity of theory of localisation
Localisation of Function in Brain: Evidence from plasticity studies fails to support localisation of function (A03) (4)
P: Evidence from plasticity studies fails to support localisation of function
E + E: When brain has become damaged through illness or accident + particular function has been lost rest of brain is able to reorganise itself to recover function eg. Turk et al discovered patient who suffered damage to left hemisphere but developed capacity to speak in right hemisphere
L: suggests that functions are not localised 1 + brain can adapt following damage to certain areas
Hemispheric lateralisation (A01)
idea that 2 halves of brain are functionally different + that certain mental processes + behaviours are mainly controlled by 1 hemisphere rather than other
human brain has 2 hemispheres which are bridged by corpus callosum-‘bridge’ which is bundle of fibres is communication pathway so that 2 hemispheres can exchange information
brain is contralateral in most people so parts of left hemisphere deal w/right side of body + right hemisphere does same for left side of body
Hemispheric lateralisation: left hemisphere (A01)
language processing is done in left hemisphere
for many people if they have stroke on left side of their brain their speech is affected
bc Broca’s + Wernicke’s areas are found on left side of brain
Hemispheric lateralisation: right hemisphere (A01)
dominant for facial recognition
case study of woman who had right hemisphere damage highlighted that right hemisphere also seems more adept at spatial relationships
woman would often get lost even in familiar situations
suggests that right hemisphere deals w/spatial information
Hemispheric lateralisation: supporting evidence (A03) (1)
P: supporting evidence
E + E: Fink used PET scans to identify which brain regions were active during visual processing task when Ps were asked to attend to global elements of an image regions of right hemisphere were more active When required to focus in on finer detail specific areas of left hemisphere were more dominant
L: suggests tasks such as visual processing are feature of connected brain
Hemispheric lateralisation: Evidence from plasticity studies fails to support lateralisation (A03) (2)
P: Evidence from plasticity studies fails to support lateralisation
E +E: When brain has become damaged through illness or accident + particular function has been lost rest of brain is able to reorganise itself to recover function eg. Turk et al discovered patient who suffered damage to left hemisphere but developed capacity to speak in right hemisphere
L: suggests that functions are not lateralised + brain can adapt following damage to certain areas
Hemispheric lateralisation: contradictory evidence against lateralisation also comes from animal research (A03) (3)
P: Contradictory evidence against lateralisation also comes from animal research
E: Lashley removed between 10-50% of cortex in rats that were learning maze + found that no area was more important than any other in terms of their ability to learn maze
E: problem as it suggests that higher cognitive processes eg. learning are not lateralised but distributed in more holistic way involving entire brain
L: reduces validity of theory of lateralisation
Hemispheric lateralisation: ‘lateralisation’ may be further complicated by age (A03) (4)
P: ‘lateralisation’ may be further complicated by age
E: means that research has shown lateralisation of function may change throughout an individual’s lifetime
E: eg. Szflarski who found that language became more lateralised to left hemisphere as children developed to adolescents but after age of 25 lateralisation decreased w/each decade of life
L: problem as it suggests hemispherical lateralisation is much more complex process than many realise w/many questions remaining as to why this happens
split brain studies VERBAL RECOGNITION: procedure (A01)
visual image eg. picture of pencil was presented to left visual field via tachistoscope
Ps were asked to describe what they had seen- would then be repeated using right visual field
split brain studies TOUCH RECOGNITION: procedure (A01)
patients’ hands were screened so they could not see objects in front of them
Ps would be asked to pick up an object using their right hand + then asked to describe what they had felt- would then be repeated using left hand
split brain studies VERBAL RECOGNITION: findings (A01)
picture of an object was shown to patient’s right visual field patient could easily describe what was seen
but if same object was shown to left visual field patient could not describe what was seen + reported that there was nothing there
bc for most people language is processed in left hemisphere + therefore when picture was presented in left visual field this was processed by right hemisphere which has a lack of language centres to be able to describe it
allows us to infer that in normal brain messages from right hemisphere would have been relayed ‘across hemispheres’ to language centres in left hemisphere to describe it
split brain studies TOUCH RECOGNITION: findings (A01)
patients could not verbally describe objects projected in their left visual field they were able to select matching object from grab-bag of different objects using their left hand
objects were placed behind screen so as not to be seen
left hand was also able to select an object that was most closely associated w/object presented to left visual field
each case patient was not able to verbally identify what they had seen but could nevertheless ‘understand’ what object was using right hemisphere + select corresponding object accordingly
split brain research: support idea lateralisation is well controlled (A03) (1)
P: support idea lateralisation is well controlled
E: means methodology can be praised for using highly standardised procedures conducted in controlled environment to control possible extraneous variables
E: eg. images were flashed up for 1-tenth of second to ensure there was not time to spread info across both sides of visual field + subsequently both sides of brain
L: positive as it ensured research measured what it intended to give evidence high internal validity
split brain research: evidence for lateralisation was flawed (A03) (2)
P: split-brain research evidence for lateralisation was flawed
E: means that findings came from very unusual + limited sample of people who were not well matched to control group eg. only 11 split-brain Ps took part in all variations of basic procedure all of whom had history of epileptic seizures + had received drug therapy for different amounts of time which may have caused unique changes in each of their brains
E: Some of Ps may also have experienced more disconnection of 2 hemispheres than others as part of their surgery-control group consisted of Ps w/no history of epilepsy making them poorly matched
L: problematic as it brings conclusions of research + support for lateralisation into doubt
Methods of Studying Brain: functional magnetic resonance imaging (fMRI) (A01)
technique for detecting changes in blood oxygenation + flow in brain
brain area is more active it consumes more oxygen + to meet this increased demand blood flow is directed to the active area
FMRI produce 3-D images showing which part of brain is involved in particular mental process
eg. P might be asked to alternate between periods of doing task + relaxed state
resulting fMRI data can then be used to identify which areas of brain were being used when doing each task
fMRI images show activity approximately 1-4 seconds after an event occurs + are thought to be accurate w/in 1-2 mm
fMRI: less invasive than other scanning techniques (A03) (1)
P: less invasive than other scanning techniques
E+ E: they don’t use radiation or require instruments to be inserted into brain
L: fMRI scans are virtually risk-free
fMRI: good spatial resolution (A03) (2)
P: good spatial resolution of 1-2 mm
E + E: Spatial resolution refers to smallest measurement that scanner can detect- Greater spatial resolution allows psychologists to investigate brain regions w/greater accuracy
L: helps researcher’s pinpoint specific responses + exact source of brain activity
fMRI: machines are expensive (A03) (3)
P: machines are expensive
E+ E: to buy + maintain + they require trained operators
L: makes research expensive + difficult to organise
fMRI: Low temporal resolution (A03) (4)
P: Low temporal resolution
E+ E: refers to the accuracy of scanner in relation to time fMRI scans have temporal resolution of 1-4 seconds which is worse than other techniques eg. EEG/ERP which have temporal resolution of 1-10 milliseconds
L: Consequently psychologists are unable to predict w/high degree of accuracy onset of brain activity
Methods of Studying Brain: electroencephalogram (EEG) (A01)
measure electrical activity w/in brain via electrodes that are fixed to an individual’s scalp using skull cap
scan recording represents brainwave patterns that are generated from action of millions of neurones providing an overall account of brain activity
can be anything from 2 to 3 electrodes to over hundred Electrodes measure activity of cells immediately under electrode so using more electrodes gives fuller picture
scan recording represents brainwave patterns that are generated from action of millions of neurones providing an overall account of brain activity
‘Real-time’ recording of brain activity
Methods of Studying Brain: event-related potentials (ERPs) (A01)
issue w/EEG is that it only provides measure of general brain activity means that brain response to single stimulus or event of interest is not usually visible in EEG recording
possible to tease out + isolate specific sensory, cognitive + motor responses w/in EEG data
stimulus such as picture or sound is presented many times to P
Using statistical averaging technique, random or background brain activity from original EEG recording is filtered out leaving only event-related potentials
ERP is 1 of most widely used methods in cognitive neuroscience research to study physiological correlates of sensory, perceptual + cognitive activity associated w/ processing information
EEG + ERP: less invasive than other scanning techniques (A03) (1)
P: less invasive than other scanning techniques
E+ E: they don’t use radiation or require instruments to be inserted into brain
L: EEG + ERP scans are virtually risk-free
EEG + ERP: cheaper methods in comparison to fMRI scanning (A03) (2)
P: cheaper methods in comparison to fMRI scanning
E+ E: more widely available to researchers
L: Consequently this could help psychologists to gather further data on functioning human brain leading to greater understanding of sleeping + disorders eg. Alzheimer’s
EEG + ERP: High temporal resolution (A03) (3)
P: High temporal resolution
E+ E: advantage of EEG/ERP technique is that it has good temporal resolution as it takes readings every millisecond meaning it can record brain activity in real time
L: leads to an accurate measurement of electrical activity when undertaking specific task
EEG + ERP: poor spatial resolution (A03) (4)
P: poor spatial resolution
E+ E: EEGs/ERPs only detect activity in superficial regions of brain Consequently EEGS + ERPs are unable to provide info on what is happening in deeper regions of brain
L: making this technique limited in comparison to fMRI which has spatial resolution of 1-2 mm
Post-mortem examinations (A01)
technique involves analysing person’s brain following their death
psychological research individuals whose brains are subject to post-mortem are likely to be those who have rare disorder + have experienced unusual deficits in mental processes or behaviour during their lifetime
Areas of damage w/in brain are examined after death as means of establishing likely cause of affliction person suffered
may also involve comparison w/ ‘normal’ brain to ascertain extent of difference
Post-mortem examinations: ethical issues (A03) (2)
P: ethical issues in relation to informed consent + whether patient provides consent before his/her death
E+ E: many post-mortem examinations are carried out on patients w/severe psychological deficits who would be unable to provide fully informed consent + yet post-mortem examination has been conducted on his brain
L: raises severe ethical questions surrounding nature of such investigations
Post-mortem examinations: provide detailed examination of structure of brain that is not possible w/other scanning techniques (A03) (1)
P: provide detailed examination of structure of brain that is not possible w/other scanning techniques
E+ E: Post-mortem examinations can access areas such as hypothalamus + hippocampus which other scanning techniques would struggle to reach
L: post-mortem examinations provide researchers w/insight into these deeper brain regions which often provide useful basis for further research
Post-mortem examinations: issue of causation (A03) (3)
P: issue of causation
E+ E: deficit patient displays during their lifetime may not be linked to deficits found in brain- deficits reported could have been the result of another illness + therefore psychologists are unable to conclude that deficit is caused by damage found in brain
L: Other confounding factors include medication person may have been taking throughout their lives length of time between death + post mortem + age of person at death
plasticity (A01)
brain’s capacity to change or adapt bc of new learning or brain trauma
well known that child’s brain changes during infancy as they acquire new knowledge + encounter new experiences but it is now known that this ability of brain does stop in childhood + that new neural connections can be made at any time of life
functional recovery (A01)
Much recovery after trauma is due to anatomical compensation brought about by intensive rehabilitation
brain learns to compensate for lost functions
brain can be taught to learn how to use working faculties + function to compensate for ones that are lost forever
functional recovery-brain after recovery: AXON SPROUTING (A01)
growth of new nerve endings which connect w/other undamaged nerve cells to form new neuronal pathways
When axon is damaged its connection w/neighbouring neurone is lost
some cases other axons that already connect w/that neurone will sprout extra connections to neurone replacing ones that have been destroyed
compensating for loss of neighbour- brain can re-wire itself by forming new synaptic connections close to area of damage
occurs for most part two weeks after damage happens
helps replace function but only if damaged axon + compensatory axons do similar job
If not problems can occur w/ function
functional recovery-brain after recovery: NEURONAL UNMASKING (A01)
some of brain’s neurones are ‘dormant’
These neurones are alive but are not doing their specific function eg. they may fail to send messages to muscle
but when brain area becomes damaged these dormant areas become ‘unmasked’
unmasking of dormant neurones opens connections in regions of brain that are not normally activated which in time gives way to development of new structures
functional recovery-brain after recovery: RECRUITMENT OF HOMOLOGOUS AREAS (A01)
opposite side of brain to perform specific tasks
eg. would be if Broca’s area was damaged on left side of brain similar area on right-side of brain would carry out its function
factors affecting recovery of brain after trauma: age (A01)
deterioration of brain in old age + this therefore affects extent + speed of recovery
study by Marquez de la Plata et al found that following brain trauma older patients regained less function in treatment than younger patients + they were also more likely to decline in terms of function for 5 years following trauma
factors affecting recovery of brain after trauma: gender (A01)
research to suggest that women recover better from brain injury as their function is not as lateralised
Ratcliffe et al examined 325 patients w/brain trauma for their level of response for cognitive skills to rehabilitation
patients were 16-45 years old at injury received rehabilitation at care facility + completed follow-up 1 year later
None of them had learning problems prior to trauma
When assessed for cognitive skills women performed significantly better than men on tests of attention/working memory + language whereas men outperformed females in visual analytic skills
factors affecting recovery of brain after trauma: physical exhaustion, stress + alcohol consumption (A01)
function is recovered in an individual it is important to remember that often function is used w/considerable effort + although person can do task they are often fatigued by effort
Other factors such as stress + alcohol consumption can affect ability to use any function that has been regained
factors affecting recovery of brain after trauma: evidence to support plasticity (A03) (1)
P: evidence to support plasticity
E+ E: Maguire et al used an MRI scanner to scan brains of London taxi drivers + found they had significantly more volume of grey matter in posterior hippocampus than matched control group- volume of this area was also positively correlated w/amount of time they had been taxi driver
L: positive as it supports idea that human brain can adapt as result of learning + experience
factors affecting recovery of brain after trauma: plasticity has contributed to treatment + rehabilitation of brain injury patients (A03) (3)
P: Understanding processes involved in plasticity has contributed to treatment + rehabilitation of brain injury patients
E+ E: Following illness or injury to brain recovery tends to slow down after few weeks so forms of physical therapy are usually performed to maintain improvements in functioning
L: shows that although brain may have capacity to ‘fix itself’ to point this process requires further intervention if it is to be completely successful
factors affecting recovery of brain after trauma: evidence to support plasticity also comes from animal studies (A03) (2)
P: evidence to support plasticity also comes from animal studies
E+ E: evidence of neuroplasticity
comes from an animal study conducted by Hubel + Wiesel- this study kittens had 1 of their eyes sewn up + brain’s cortical responses were analysed- found that area of visual cortex associated w/shut eye was not idle but continued to process info from open eye
L: positive as it supports idea that brain can change or adapt as result of experience
factors affecting recovery of brain after trauma: functional recovery is affected by individual differences (A03) (4)
P: functional recovery is affected by individual differences
E: appears that certain individuals may have more of an ability to recover from brain trauma than others eg. Elbert et al showed that adults require far more intensive training than children after brain trauma
E: Schneider et al found that patients w/college education were seven times more likely than those who didn’t finish high school to be disability-free 1 year after brain injury
L: suggests no. of factors contribute to brain plasticity + recovery from brain trauma which makes it complex area to study
biological rhythms (A01)
natural cycle of change in our body’s chemicals or functions
rhythms are governed by 2 things: body’s internal body clocks + external changes to environment
biological rhythms: cardiac rhythms (A01)
cycle in biological or psychological activity that occurs once every 24 hours
most obvious example is sleep-wake cycle which occurs once every day
eg. include core body temp also follows daily rhythm as it is highest at around 4pm + lowest at around 4am
cardiac rhythms: hormone production (A01)
Hormone release follows circadian rhythm eg. production + release of melatonin from pineal gland in brain follows circadian rhythm w/ peak levels occurring during hours of darkness
activating chemical receptors in brain melatonin encourages feelings of sleep
dark more melatonin in produced + when it is light again production of melatonin drops + person wakes
cardiac rhythms: sleep-wake cycle (A01)
circadian rhythm not only dictates when we should be sleeping but also when we should be awake
Light + darkness are external signals that determine when we feel need to sleep + when to wake up
circadian rhythm also dips + rises at different times of day so our strongest sleep drive usually occurs in 2 ‘dips’ between 2-4 am + between 1-3 pm
cardiac rhythms: practical application (A03) (1)
P: practical application
E+ E: Research into circadian rhythms provides an understanding of consequences that occur when they are disrupted eg. night workers experience reduced concentration around 6am
L: leading to an increase in mistakes + accidents
cardiac rhythms: small sample size (A03) (2)
P: small sample size
E+E: e.g. Siffre did study providing insight on nature of cardiac rhythms and how they can be influenced by biological factors and effects of isolation on human biological rhythms however cardiac cycles for Siffre may not be generalisable for everyone so him having sleep wake cycle of 25 hours in the cave without any natural light or external time cues may vary for all different types of people
L: weakness as it decreases validity and it makes it harder to find any significant effects or relationship between our sleep wake cycle in cardiac rhythms and external/internal cues
biological rhythms: infradian rhythms (A01)
last more than 24 hours eg. include menstruation breeding, hibernation + seasonal affective disorder
infradian rhythms: support by theory of evolution (A03) (1)
P: support by theory of evolution
E+ E: eg. may have been advantageous for women to menstruate together + become pregnant at same time -In social group this would allow babies who had lost their mothers during childbirth to have access to breast milk thereby improving their chances of survival
L: suggests that synchronisation of menstrual cycle is an adaptive strategy
infradian rhythms: menstrual cycle (A01)
woman’s menstrual cycle is monthly infradian rhythm that is governed by monthly changes in hormones that regulate ovulation
typical cycle lasts 28 days
During each cycle rising levels of hormone oestrogen cause ovary to release an egg
After ovulation hormone progesterone helps womb lining to grow thicker readying womb for pregnancy
If pregnancy does not occur egg is absorbed to body womb lining comes area + leaves body
infradian rhythms: research (A01)
McClintock: 29 women w/irregular periods were studies
Samples of pheromones were gathered from 9 of women at different stages of their menstrual cycles via cotton pad placed in their armpits pads were then rubbed on upper lip of other Ps
Stern + McClintock found that 68% of women experienced changes to their cycle which brough them closer to cycle of their ’odour donor’
infraradian rhythms: limitations to synchronisation studies (A03) (2)
P: limitations to synchronisation studies
E+ E: eg. there are many factors that may cause menstrual cycle to change, including stress, extreme dieting + exercising
L: weakness bc it make show that infraradian rhythms lack reliability and application of research findings
ultradiation rhythms: stages of sleep (A01)
Stages 1: this is light sleep where person may be easily woken- alpha brain waves occur
Stage 2: Light sleep continues
Sleep spindles also occasionally occur
Stages 3 + 4: deep sleep or slow wave sleep
Delta waves occur w/lower frequency + higher amplitude difficult to wake someone at this point.
Stage 5: body is paralysed yet brain activity closely resembles that of awake brain
brain produces theta waves + eyes move around- Dreams are most often experienced during REM sleep
biological rhythms: ultradiation rhythms (A01)
Ultradian rhythms are biological rhythms lasting less than 24 hours
eg. of ultradian rhythms include eye blinking, heartbeats, sleep patterns, breathing, pulse, appetite + digestion
When we sleep we go through 5 distinct stages that span about 90 minutes
cycle starts at light sleep progressing to deep sleep + then REM sleep
repeats itself about every 90 minutes throughout night typical person will go through about 5 full cycles in full night’s sleep
ultradiation rhythms: improved understanding of age-related changes in sleep (A03) (1)
P: improved understanding of age-related changes in sleep
E+ E: eg. sleep scientists have observed that SWS reduces w/age leading to reduced alertness in elderly it has also helped by improving sleep quality and addressing age related changes in sleep by promoting depper sleep,enhancing efficiency and supporting cognitve function
L: suggests that knowledge of ultradian rhythms has practical value
ultradiation rhythms: ignores individual differences (A03) (2)
P: ignores individual differences
E+ E: Tucker found large differences in duration of each sleep stage in many Ps so his study may lead to overgeneralisation about effectiveness of ultraradian rhyhms improving sleep, if indivual differences are ignored then it can result in recommendations that dont apply to everyone-could lead to ineffective sleep strageries
L: makes it difficult to describe ‘normal sleep’ and it limits effectiveness and applicabilty of findings in real world scienarios
endogenous pacemakers + sleep wake cycle: suprachiasmatic nucleus (SCN) (A01)
SCN is tiny bundle of nerve cells located in hypothalamus plays an important role in maintaining circadian rhythms eg. sleep/wake cycle SCN is damaged or destroyed, sleep becomes erratic
SCN lies just above the optic chaism receives information about light directly from this structure continues even when our eyes are closed
enabling biological clock to adjust to changing patterns of daylight whilst we are asleep
our biological clock is running slow then morning light automatically adjusts clock putting its rhythm in step w/world outside
synronisation of SCN by changes in light is known as entrainment
endogenous pacemakers (A01)
internal body clocks that regulate many of our biological rhythms
endogenous pacemakers + sleep wake cycle: pineal gland + melatonin (A01)
SCN passes info on day length + light to pineal gland
During night pineal gland increases production of melatonin chemical that induces sleep and is inhibited
during period of wakefulness
Melatonin has also been linked to seasonal affective disorder (SAD)
endogenous pacemakers + sleep wake cycle: supporting evidence (A03) (1)
P: supporting evidence
E: support idea that SCN is key endogenous pacemaker in sleep-wake cycle comes from Morgan Studying hamsters it was found that if SCN was removed circadian sleep-wake cycle completely disappeared
E: Transplanting SCN cells from foetal hamsters to these hamsters helped to re-establish sleep-wake cycle if hamster was given transplanted SCN from mutant strain of hamster w/shorter sleep-wake cycle of 20 hours it will adopt the same activity patterns as mutant donor
L: animal studies support view that SCN is vital in maintaining sleep-wake cycle
endogenous pacemakers + sleep wake cycle: case study of Siffre lends further support for role of SCN (A03) (2)
P: case study of Siffre lends further support for role of SCN
E+E: Siffre lived underground in cave in Texas for 6 months w/X external cues such as daylight- was found that his sleep-wake cycle settled to ‘free-running’ rhythm of around 25 hours- study suggests endogenous pacemakers such as SCN are important in controlling sleep-wake cycle
L: Despite absence of any exogenous zeitgebers Siffre was able to maintain relatively normal cycle
endogenous pacemakers + sleep wake cycle: practical application (A03) (3)
P: real world application for role of endogenous pacemakers in circadian rhythms
E+ E: eg. our circadian rhythms affect when drugs are most affective therefore when prescribed drugs it is now advised that they are taken at different times of day to maximise their effects
L: suggests that we have an internal clock that controls our 24-hour sleep-wake cycle as medication is advised to be taken around this cycle
exogenous Zeitgebers + sleep wake cycle: social cues (A01)
mealtimes, bedtimes + social events also act as zeitgeber
Research also suggests that adapting to local times for eating + sleeping is an effective way on entraining circadian rhythms + beating jet lag when travelling long distances
endogenous pacemakers + sleep wake cycle: contradictory evidence (A03) (4)
P: contradictory evidence
E+ E: Folkard studied university student Kate Aldcroft who volunteered to spend 25 days in controlled environment of laboratory- During her time in lab she had no access to daylight or other zeitgebers that might have reset SCN end of 25 days her sleep-wake cycle had extended to 30 hours
L: reduces validity of role of endogenous pacemakers in sleep-wake cycle as it appears that exogenous zeitgebers are required to synchronise SCN
exogenous Zeitgebers + sleep wake cycle: light (A01)
important zeitgeber in humans
It helps to maintain sleep–wake cycle by resetting SCN
Receptors in SCN are sensitive to changes in light levels during day + use this information to synchronise activity of body’s organs + glands
Light resets internal biological clock each day keeping it on 24-hour cycle
exogenous Zeitgebers + sleep wake cycle: supporting evidence (A03) (1)
P: supporting evidence
E+ E: role of exogenous zeitgebers in circadian rhythm control comes from Campbell and Murphy- found that shining light on back of participants’ knees shifted circadian rhythm
L: implies that natural light plays role in ‘entraining’ our biological clocks to keep sleep-wake cycle in synchrony w/outside world
exogenous Zeitgebers + sleep wake cycle: contradictory evidence (A03) (3)
P: contradictory evidence
E+ E: Miles studied young man who was blind from birth Despite exposure to social cues such as regular mealtimes his sleep/wake cycle remained abnormal
L: suggests that social cues alone are not effective in resetting biological rhythm
exogenous Zeitgebers + sleep wake cycle: practical application (A03) (2)
P: practical application
E+ E: Research on exogenous zeitgebers has led to treatments for jet lag eg. Burgess et al found that exposure to bright light prior to an east-west flight reduced jet lag Ps who were exposed to bright light felt sleepier 2 hours earlier in evening + woke 2 hours earlier in morning eg. closer to local times conditions they would find after an east-west flight
L: huge benefits to economy as preventing jet lag increases productivity eg. people are more likely to return to work earlier if they are less sleepy
