biopsychology Flashcards
what two subdivisions is the NS divided into
- central ns
- peripheral ns
CNS
- consists of brain and spinal cord
- collects and processes sympathetic ns and responds to stimuli in the environment and coordinates working of different organs in the body
PNS
- relays messages (nerve impulses) from CNS to rest of body
what is the PNS divided into
somatic ns
autonomic ns
ANS
- important in homeostasis: maintains internal processes like bodily temperature, heart rate and blood pressure
- consists of motor pathways and 2 subcomponents
SNS
- maintains communication between CNS and outside world
- made up of sensory receptors that carry info to spinal cord, brain and motor pathways.
- provides muscle responses via motor pathways
what is the endocrine system
- a network of glands across the body that secretes hormones through the blood
glands that are a part of the endocrine system
- pineal
- thyroid
- ovaries
- testes
- adrenal gland (medulla)
- adrenal gland cortex
- hypothalamus
- pituitary
pineal gland
- secretes melatonin,
- sleep wake cycle
thyroid gland
- secretes thyroxine
- regulates metabolism
ovaries
- secretes oestrogen
- regulates female reproduction
testes
- secretes testosterone
- development of male sex characteristics
adrenal gland (medulla)
- secretes adrenaline and noradrenaline
- adrenal gland cortex
- secretes cortisol
- stimulates release of glucose
hypothalamus
- stimulates release of hormones from pituitary gland
pituitary gland
- master gland
- hormones released from here
- controls and stimulates other glands
process of stimulating a fight or flight response
- hypothalamus triggers ANS (sympathetic branch)
- ANS stimulates adrenal medulla
- adrenaline and noradrenaline to be released into the blood
- fight or flight response triggered
structure and function of motor neurons
- short dendrites, long axons
- connects CNS to receptors
- found in PNS and controls muscle movement
structure and function of relay neurons
- short dendrites and axons
- connects sensory and motor neurons
- allows fast reflex responses by bypassing the brain
structure and function of sensory neurons
- long dendrites, short axons
- found in receptors
- not all sensory receptors reach brain
firing of a neuron process
- neuron at resting state = negatively charged
- when neuron activated by a stimulus, inside of cell becomes positively charged for a split second
- action potential will pass through the neuron when positively charged
- allows an electrical impulse to move through the neuron
synaptic transmission
method of neurons communicating with each other
process of synaptic transmission
- vesicles release neurotransmitter into synaptic cleft
- neurotransmitters bind to receptors and activates them
- excess neurotransmitters are taken up by presynaptic neuron
- enzymes released to break down remaining neurotransmitters
- vesicles replenished with new and reused neurotransmitters
what are neurotransmitters
- chemical messengers in the body: transmit signals
- found in brain and spinal cord
- across synaptic cleft
neurons can either have a _ effect or _ effect on a neighbouring neuron
- excitory or inhibitory
excitation
- increases likelihood of happening
- adrenaline causes excitation by increasing a neuron’s positive charge and makes it more likely to fire
inhibition
- decreases likelihood of happening
- seratonin causes inhibition in neighbouring neuron, causes it to be charge, less likely to fire
summation
- addition of inputs
2 types of summation
spatial
temporal
spatial summation
- 2 or more inputs arrive from different presynaptic cells to same synapse at same time
temporal summation
- 2 or more action potentials arrive in rapid succession along a single presynaptic neuron
localisation is
each area of the brain has a specific function
motor cortex
region of frontal lobe involved in regulating voluntary movement
somatosensory cortex
area of parietal lobe that processes sensory information such as touch
visual cortex
part of occipital lobe that receives and processes visual information
auditory cortex
located in temporal lobe, analysis of speech based information
Broca’s area
area of frontal lobe of brain in the left hemisphere - responsible for speech production
Wernicke’s area
area of temporal lobe in left hemisphere - language comprehension
case study to support localisation of function
unique cases of neurological damage support the idea of localisation of function e.g phineas gage:
- tamping iron pole through his head
- took most of his left front lobe
- he used to be calm but after the accident he was short tempered and rude
- this suggested that the frontal lobe may be responsible for regulating mood.
evaluation of phineas gage
good:
- they are able to help more people that have similar injuries to Phineas Gage and are able to predict the changes to behaviour when a part of the brain was damaged.
- this makes the study more applicable.
bad:
- this is a case study that they did only on Phineas Gage.
- which would make the chances of someone having the same type of damage very low, therefore the study lacks generalisability.
brain scan evidence to support localisation of function
peterson et al 1988:
- used brain scans to show how Wernicke’s area was active during a listening task and Broca’s area during a reading task - suggests these areas of the brain have different functions
tulving et al:
- semantic and episodic memories reside in different parts of the prefrontal cortex
these studies support the idea of localisation of function theory. in addition, these provide scientific evidence of localisation of function which improves the validity of this concept
neurological evidence to support localisation of function theory
surgically removing or destroying areas of the brain to control aspects of behaviour was developed by Walter Freeman - however they were imprecise and unreliable
- dougherty et al reported on 44 OCD patients who had a ‘cingulotomy’ (lesioning of cingulate gyrus) . at a 32 week follow up, 1/3 of the patients met the criteria for a successful response to the surgery and 14% with a partial response
success of these procedures strongly suggests the symptoms and behaviours associated with serious mental disorders are localised
role of left hemisphere
control of right hand, right visual field, speech, understanding written language, understanding what is heard, logical thinking
role of right hemisphere
control of left hand, left visual field, spatial awareness, creativity, recognising faces, musical ability
how does Broca’s and Wernicke’s aphasia support localisation?
damage to specific brain areas results in loss of function and so suggests they are localised to those brain areas.
limitation of localisation of function theory
holistic theory proposed by Lashley
- suggested that there were higher cognitive functions e.g processes involved in learning are not localised by distributed in a more holistic way
- lashley removed these areas of the cortex in rats that were learning a maze. no area was more important than any other area in terms of the rat’s ability to learn the maze
- as learning required every part of the cortex rather than just particular areas, this suggests learning is too complex to be localised and involves the whole brain
neural plasticity as a limitation to the localisation of function theory
- when the brain has become damaged and a function has become compromised or lost, the rest of the brain is able to reorganise themselves in an attempt to recover the lost function
- lashley called this the law of equipotentiality whereby surviving brain circuits help so same neurological action can be achieved
supporting and limiting factors to localisation of function theory
supports:
neurological evidence
brain scan evidence
limits:
neural plasticity
holistic theory
plasticity definition
brain’s tendency to change and adapt as a result of experience and learning
synaptic pruning
rarely used connections are deleted and frequently used connections are strengthened
studies to support plasticity
Maguire 2000
- studied brains of London taxi drivers and found significantly more grey matter in posterior hippocampus than matched control groups.
- this part of the brain is associated with development of spatial and navigational skills
- spatial learning alters brain structure
evaluation of study to support plasticity
pros:
- no ethical considerations
- one experienced individual carried out the brain scans so theres consistency in the measurements of hippocampal volume = reliable
- neuroplasticity seen in hippocampus of taxi drivers can possibly be extended to other regions of the brain, using suitable environmental cues to stimulate them + cause positive change.
cons:
- the scanning technique used by Maguire is costly so therefore it is harder to replicate and test results
- sample is not exactly typical of the general population. May be not everyone’s brain could or would respond in the same way to the environmental demands of doing ‘The Knowledge’ and being a taxi driver in London.
functional recovery after trauma
another example of neural plasticity
- unaffected areas of brain compensate and adapt for damaged areas
structural changes in the brain
- axonal sprouting
- reformation of blood vessels
- recruitment of homologous areas
axonal sprouting
growth of new nerve ending which connect with other undamaged nerve cells to form neural pathways
reformation of blood vessels
haemodynamic response
- activated areas experience a higher blood deoxygenated level
recruitment of homologous areas
- when a homologous area of the brain on the opposite side of the brain (undamaged) is used to perform a specific task
case study to support plasticity
draganski et al:
- imaged brains of medical students 3 months before and after final exams.
- learning induced changes occurred in posterior hippocampus and parietal cortex
mechelli et al
- recruited 25 monolinguals who had little or no exposure to a second language, 25 early billinguals who learned a second european language before the age of 5 years and who practiced regularly since, and 33 late billinguals who learned a second language between ages 10 and 15
- all ptps were native english speakers of comparable age and level of education
- larger volume of grey matter density in inferior parietal cortex present in bilingual people
individual differences that affect functional recovery
- severity of injury
- stress and response to treatment
- age
- level of education
- pre existing environmental, genetic medical condition
practical applications of research into plasticity and recovery
- helpful in neurorehabilitation field
- techniques may include movement therapy and electrical stimulation of brain to counter deficits in motor and/or cognitive functioning
negative plasticity
- brains ability to rewire itself can have negative consequences.
- e.g prolonged drug use can result in poorer cognitive functioning and increased risk of dementia (medina et al)
animal research into plasticity
hubel and weisel:
- sewed one eye of a kitten shut and analysed the brain’s cortical responses
- area of visual cortex associated with shut eye was not idle but continued to process information from the open eye
- demonstrates how loss of function leads to compensatory activity in the brain: evidence of neural plasticity
- evidently has ethical issues: purposefully harming an animal in the name of science
age and plasticity
- functional plasticity reduces with age.
- bezzola et al demonstrated how 40 years of golf training produced changes in the neural representation of movement in ptps aged 40-60
- shows that neural plasticity does continue throughout our lifespan
cognitive reserve
- educational attainment may influence how well brain functionally adapts after an injury
- schneider et al discovered that the more time brain injury patients had spent in education, the greater their chances of a disability free recovery
- suggests that cognitive reserve is a crucial factor in determining how well the brain adapts after trauma
pros and cons to neural plasticity
cons:
negative plastcity
age and plasticity’s relationship is complex
neural plasticity may be related to cognitive reserve
pros:
neural plasticity is supported by animal studies
hemispheric lateralisation
2 halves of the brain are functionally different and that each half has a specialised function
studies to support hemispheric lateralisation
split brain studies - sperry:
- involved a group of individuals, all of whom had undergone a surgical procedure where the corpus callosum and other tissues which connect the two hemispheres were cut down the middle in order to seperate the two hemispheres.
- this allowed sperry to see the extent to which the two hemispheres were specialised for certain functions.
rogers et al:
- found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously (finding food and being vigilant for predators) using only one
hemisphere to engage in a task leaves the other hemisphere free to engage in
other functions.
- this provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in
cognitive tasks.
- however, because this research was carried out on animals, the results cannot be generalised to humans
- such studies also include very few participants
- therefore, any conclusions drawn are
representative only of those individuals who had a confounding physical
disorder that made the procedure necessary.
sperry’s study procedure
- an image or word would be projected to individual’s right visual field (processed by left hemisphere) and the same/different image could be projected to the left visual field
- in the normal brain, the corpus callosum would immediately share the info between hemispheres however, presenting the image to one hemisphere of a split brain individual meant that the info would not be conveyed from one hemisphere to another
sperry’s study findings - describing what you see
describing what you see:
- when pic of object shown to right visual field, they could easily describe what was seen
- if same object shown to left visual field, they couldn’t describe what was seen
- language processed in left hemisphere, thus individual’s inability to describe objects in the left visual field was because of the lack of language centres in left hemisphere
sperry’s study findings - recognition by touch
recognition by touch:
- if an object was projected in left visual field, they were able to grab a matching object from a bag of diff objects using left hand
- if objects were placed behind a screen, the left hand was also able to select an object that was most closely associated with the object presented in left visual field (e.g ashtray picked up in response to pic of a cigarette)
- individuals not able to verbally describe what the object was but they could understand what the object was and select corresponding object accordingly
sperry’s study findings - composite words
- if two words presented simultaneously, one on either visual field, (‘key’ on left and ‘ring’ on right) the individual would select a key with their left hand and say the word ring
- implies that speech and language is localised in the left hemisphere.
sperry’s study findings - matching faces
- right hemisphere also appeared dominant in terms of recognising faces.
- when asked to match a face from a series of other faces, the picture processed by right hemisphere was consistently selected, whilst pic presented to left was consistently ignored.
- when composite pic made up of 2 different halves of a face were presented (one half to each hemisphere), the left hemisphere dominated in terms of verbal description whereas right dominated in selecting a matching picture
conclusions drawn from study on lateralised brain function
sperry:
- left hemisphere is more geared towards analytic and verbal tasks, whilst the right is better at performing spatial tasks and music (speech and language)
- the right hemisphere can only produce rudimentary words but contributes emotional and holistic content to language (visual motor tasks)
evaluation of study on hemispheric laterlisation
strengths:
- highly specialised and standardised procedures
- allowed sperry to vary aspects of the basic procedure and ensured only one hemisphere was receiving information at a time: developed a very useful and well controlled procedure
problems:
- sample issues: only 11 people took part in all variations of the basic procedure, all of whom had a history of epileptic seizures. may have caused unique changes in the brain that may have influenced the findings.
- difference in function may be overstated: modern neuroscientists would contend that the actual distinction is less clear out and much more messy than this
study to refute hemispheric laterlisation
turk et al:
- discovered a patient who suffered damage to the left hemisphere but developed the capacity to speak in the right hemisphere, eventually leading to the ability to speak about the information presented to either side of the brain.
- this suggests that perhaps lateralisation is not fixed and that the brain can adapt following damage to certain areas.
studies that support and refute hemispheric lateralisation
support
- sperry
- rogers
refute:
- turk
FMRI
- measures brain activity whilst performing a task. produces 3D image
- more oxygen flow = more active
- detects changes in blood oxygenation and flow that occurs as a result of brain activity
EEG
- electrodes placed on scalp to record brainwave activity
- often used as diagnostic tool
- unusual arrhythmic patterns may indicate neurological abnormalities
ERP
- brain’s response to a specific event can be isolated through statistical averaging techniques
- different forms of ERPs linked to cognitive processes
post mortems
- analysis of brain to see if observed behaviours can be linked to abnormalities in the brain
- can be compared to a healthy brain
ways of investigating the brain
- FMRI
- EEG
- ERP
- post mortems
evaluating FMRI
- no radiation
- risk free, non invasive
- straight forward to use
- high spatial recognition
- patient has to be very still
- very expensive
- poor temporal resolution: 5 second time lag behind image on screen and firing of neuronal activity
evaluating EEG
- important in diagnosis of conditions such as epilepsy
- contributed to understanding stages of sleep (ultradian rhythms etc)
- high temporal resolution: can detect brain activity at a resolution of a single millisecond
- generalised nature of the information received. EEG signal is not useful for pinpointing the exact source of neural activity, and doesn’t allow researchers to distinguish between activities originating in adjacent locations
evaluating ERPs
- partly addresses limitations of EEGs: bring much more specificity to measurement of neural processes compared to EEGs
- excellent temporal resolution which has led ERPs to their widespread use
- researchers have been able to identify many different types of ERPs and describe their precise role of these in cognitive functioning
evaluating post mortems
- evidence has been vital for research into early understanding of the key processes of the brain. For example, Paul Broca and Karl Wernicke both relied on post mortem studies to establish links between language, brain etc
- post mortems help improve medical knowledge
- issue of causation: observed damage to brain may not be linked to deficits under review but due to decay or trauma.
- lack of informed consent. e.g HM lost his ability to form memories and provide consent but post mortem research was conducted on his brain
biological rhythms are
cyclic changes in level of bodily chemical or function
circadian rhythms …
type of biological rhythm
- occurs once every 24 hours
studies to explain the concept of the sleep wake cycle
- siffre’s cave studies
- aschoff and wever’s bunker
- folkards cave
- cziesler et al
siffre’s case study
- spent multiple extended periods underground to study the effect of his own biological rhythms
- he didn’t have any natural light or sound but had access to food and water
- resurfaced in sep 1962 after spending 2 months in the cave thinking it was mid august
- he settled into a sleep-wake cycle of 24 hours and 30 minutes
- a decade later he performed the same study but for 6 months in a texan cave
- for the first 35 days, siffre had a sleep wake cycle of 26 hours
siffre case study evaluation
- siffre controlled the main extraneous varialbes to observe their effects
- as he was underground for so long, he was able to gather qualitative and quantitative data which produced a detailed record of his time.
- when siffre woke up, lights were put on, when he went to sleep, they were turned off. the lights could’ve acted as an external cue, which affects the study’s internal validity
- siffre was the only ptp in this study = hard to generalise findings to other people
- living in a cave, can have particular effects e.g its cold, which can affect behaviour
- another weakness is that Siffre’s study only accounts for biological influences on the circadian rhythm and so only represents the nature side of the nature-nurture debate. this provides an unrealistic view of human behaviour as in real life both nature and nurture interact with one another.
aschoff and wever’s bunker
- convinced a group of ptps in a WWII bunker for 4 weeks, deprived of natural light
- all but one ptp displayed a circadian rhythm of between 24 and 25 hours.
- both this study and siffre’s study suggest that the ‘natural’ sleep/wake cycle may be slightly longer than 24 hours but that is caused by exogenous zeitgebers associated with our 24 hour day e.g daylight hours
aschoff and weaver’s case study evaluation
- small sample size therefore results cannot be generalised to the general population as the results don’t account for individual differences
(supports siffre’s case study so use same evaluation points)
folkard’s cave
- isolated 12 ptps from natural light for 3 weeks in a dark cave
- retiring to bed when the clock said 11:45 and waking up when it said 7:45
- the clock only had 22 hours on it and the researchers didn’t allow the ptps to adjust to the pace of the clock comfortably, as they gradually sped up the clock (unbeknownst to the ptps) so a ‘24 hour’ day eventually lasted 22 hours
- only one ptp comfortably adjusted to the new regime
- this suggests the existence of a strong free-running circadian rhythm that cannot easily be overridden by changes in the external environment
folkard’s cave evaluation
- strength of this study is that both endogenous pacemakers and exogenous zeitgebers were accounted for, so this is representative of both sides of the nature-nurture debate, thus reflecting real life. This takes a holistic approach to human behaviour, as opposed to being reductionist.
- folkard used a volunteer sample, which may mean that the results could not be generalised to the wider population, as certain types of people tend to volunteer to participate in studies; therefore the findings may have low population validity.
czeisler et al
- investigated whether night shift workers’ alertness and sleeping would improve with light-dark reversal treatment
- 2 conditions:
- in the control condition, the men were asked to use their home setting for any day time sleeping they required. for this sleeping was left unregulated and naturalistic
- in the experimental condition the ptps daytime sleeping at home was treated to having opaque windows and artificial darkness enforced
- each came to the lab at 23:45 for 6 days of shifts that involved staying awake, doing cognitive tests and reporting their own alertness and mood.
- men in experimental group were exposed to very bright light during the night shift
- biological measures e.g body temp, showed that the experimental group had their own circadian rhythms adjusted forward by 9 hours, control group’s stayed the same
- body temp of control group was lowest (3.31) in the night while on night shift, whereas experimental group was 14.53 in afternoon whilst sleeping at home
- therefore men’s daytime sleeping pattern more successfully adapted to a daytime circadian rhythm
cziesler et al sample
sample: 8 healthy men in 20s, none of whom regularly worked nights shifts
cziesler et al conclusion
- conclusion: usual circadian maladjustment to night shift work can be treated and reversed with exposure to light at night and dark during the day
cziesler et al evaluation
- study can be directly applied to shift work patterns
- it has important implications for improving night worker productivity
- could also reduce the risk of accidents at work during the night and increase worker’s health and safety
- light dark treatment was implemented in a ecologically valid setting - men’s homes. also had a high degree of lab control for its night measurements
- small sample size: 8
- gender biased: men, making it harder to generalise results to wider population
- night shift work was simulated in a lav which mat not have reflected typical working conditions: work involved sitting in a chair for the duration of the night - may lack ecological validity for certain night shift workers
- certain extraneous variables were not fully controlled e.g when they ate etc
overall evaluation of sleep wake cycle studies
- control not perfect = still artificial light
- low population validity: siffre
- the conclusions from this study can be applied to work shifts = knowledge of circadian troughs (Bolvin 1996) helped inform workplaces of how to avoid accidents like Chernobyl
infradian rhythms
take longer than 24 hours to complete
SAD
seasonal affective disorder
- often referred to as the ‘winter blues’ as the number of daylight hours decrease during the winter
- SAD is a particular type of infradian rhythm (circannual rhythm) as its subject to a yearly cycle
- psychologists have hypothesised that melatonin is implicated in the cause of SAD
- pineal gland secretes melatonin until dawn when there is an increase in sunlight. during winter, the lack of light in the morning means this secretion process goes on for longer
- causes a knock on effect on the production of seratonin in the brain - linked to onset of depressive symptoms
menstrual cycle
example of infradian rhythm
- endogenous system
- typical cycle lasts 28 days
entrainment definition
be in rhythm with
study to support idea of the menstrual cycle being influenced by exogenous factors
McClintock - sweaty lip ladies
- gathered 29 women with a history of irregular periods
- samples of pheromones were collected from 9 women at different stages of their cycles via their armpit…
- the pads were worn for at least 8 hours to ensure the pheromones were picked up
- pads were treated and frozen, to be rubbed on the upper lip of the ptps
- one day 1, pads from the beginning of the cycle were applied to the 20 women. on day 2 there were given the pads from day 2 of the menstrual cycle etc.
- McClintock found that 68% of women experienced changes to their cycle which bought them closer to the cycle of their ‘cycle donor’
evaluation of study to support idea of the menstrual cycle being influenced by exogenous factors
mcClintock
- commentators argue that there are many factors that can may induce change in a woman’s menstrual cycle. e.g stress, alcohol, exercise etc, these may count as extraneous variables
-research relies on ptps self reporting the onset of their own cycle.
- other studies (trevathan 1993) failed to find any evidence of menstrual synchrony in all female samples
