What are the functions of the nervous system?
1) Collect, process and respond to info in the environment.
2) Co-ordinate working of different organs and cells.
What is the nervous system subdivided in to?
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What is the CNS made up of?
The brain and spinal cord.
What distinguishes human mental functions from those of animals?
In terms of the nervous system, what does the spinal cord do?
- Responsible for reflex actions.
- Passes messages to and from the brain and connects nerves to the PNS.
What is the PNS subdivided in to?
- Autonomic Nervous System
- Somatic Nervous System
What is the Autonomic Nervous System responsible for?
- Governs vital functions in the body such as breathing, heart rate, digestion etc.
What is the Somatic Nervous System responsible for?
Controls muscle movements and receives information from sensory receptors
What are glands responsible for?
- Production of hormones.
- Major endocrine gland is the pituitary gland, often called ‘master gland’ as it controls release of hormones from all other endocrine glands in the body.
What are hormones responsible for?
- Secreted in the bloodstream and affect any cell in the body that has a receptor for that particular hormone.
- Diverse and powerful responses.
- E.g. Thyroid gland releases thyroxine which increases heart rate and metabolic rate
The endocrine system and ANS work together to administer what
The Fight or Flight response
In terms of the fight or flight response, what happens when a stressor is perceived?
- The hypothalamus triggers activity in the sympathetic branch of the Autonomic Nervous System
What is the ANS responsible for in the fight or flight response?
Changing from its resting state (parasympathetic) to the physiologically aroused, sympathetic state.
Adrenaline is released from where, and what is it responsible for?
- Adrenal medulla
- Creates arousal necessary for fight or flight response.
Give 3 examples of the body at the sympathetic state
- Increased heart rate.
- Increased breathing rate.
- Dilated pupils
Give 3 examples of the body at the parasympathetic state
- Decreased heart rate
- Decreased breathing rate.
- Constricted pupils
What happens once the ‘stressor’ has passed?
- The parasympathetic nervous system returns the body to its resting state.
- Parasympathetic is antagonistic to the sympathetic system.
What are the 3 types of neurons?
What is the sensory neuron responsible for?
- Carries messages from the PNS to CNS.
- Long dendrites and short axons.
What is the relay neuron responsible for?
- Connects the sensory neurons to motor or other relay neurons.
- Short dendrites and short axons.
What is the motor neuron responsible for?
- Connects the CNS to effectors such as muscles and glands
- Short dendrites and long axons.
In what order do the neurons come?
1) Sensory ... then ... 2) Relay ... then ... 3) Motor ... then ...
What is in the structure of a neuron?
1) Cell body
; myelin sheath
; nodes of Ranvier
4) Terminal buttons
What is a cell body?
- Includes a nucleus which contains the genetic material of the cell.
What does a dendrite do?
- Branches protruding from cell body, carrying nerve impulses from other neurons to towards the cell body.
What does an axon do?
- Carries electrical impulse away from the cell body down the length of the neuron.
- Covered in a fatty layer of myelin sheath that protects the axon.
- Gaps in the axons called nodes of Ranvier speed up the transmission of the impulse
What do terminal buttons do?
- At the end of the axon; communicate with the next neuron in the chain across the synapse.
What happens when a neuron is activated by a stimulus?
- The inside of the cell becomes positively charged for a split second, causing an action potential to occur
= electrical impulse, moving it down the axon
(i) How are signals within neurons transmitted?
(ii) How are signals between neurons transmitted?
What happens when the electrical impulse reaches the end of the neuron (presynaptic terminal)?
- Triggers the releases of neurotransmitters from synaptic vesicles
What happens when the neurotransmitter crosses the synaptic cleft?
It is taken up by the postsynaptic receptor sites on the next neuron
In terms of synaptic transmission, what are neurotransmitters? Give an example of a neurotransmitter and what it’s responsible for.
- Chemicals that diffuse across the synapse
- Serotonin - affects mood and social behaviour.
What is inhibition? Give an example of inhibitory neurotransmitter
- Increases the negative charge of the postsynaptic neuron, making it less likely the neuron will fire.
- e.g. Serotonin
What is excitation? Give an example of excitatory neurotransmitter
- Increases the positive charge of the postsynaptic neuron, making it more more likely the neuron will fire.
- e.g. Adrenaline.
What is the definition of localisation of function (in the brain) ?
- The theory that different areas of the brain are responsible for different behaviours, processes or activites.
What does the localisation of function theory juxtapose?
Holism - the idea that all parts of the brain were involved in the processing of thought and action
The brain is divided into what?
-Two symmetrical halves called the left and right hemispheres.
What side of the brain controls what side of the body?
- Left hemisphere controls right side of the body.
- Right hemisphere controls the left side of the body.
The cortex of both hemispheres is divided into how many lobes, can you name them too?
1) Frontal lobe
2) Parietal lobe
3) Occipital lobe
4) Temporal lobe
What is the back of the frontal lobe responsible for?
- Motor area which controls voluntary movement in the opposite side of the body.
What is the front of the parietal lobes responsible for?
- Somatosensory area.
- This is where sensory info from the skin (touch, heat, pressure) is represented.
What is the occipital lobe responsible for?
- Visual area.
- Each eye send info from the right visual field to the left visual cortex and vice versa.
What is the temporal lobe responsible for?
- Auditory area.
- Analyses speech-based info.
- Damage may produce hearing loss.
Where is Broca’s area located and what is it responsible for?
- Left frontal lobe.
- Speech production.
What is the term for damage to Broca’s area and what are the consequences of damage to this area?
- Broca’s aphasia.
- Slow, laborious, lacking fluency speech.
Where is Wernicke’s area located and what is it responsible for?
- Left temporal lobe.
- Language comprehension.
What is the term for damage to Wernicke’s area and what are the consequences of damage to this area?
- Wernicke’s aphasia.
- Severe difficulty in understanding language but can produce it with no problem.
What evidence is there from brain scans to support the localisation theory?
- Peterson et al. (1988)
- Showed Wernicke’s area was active during a listening task, and Broca’s area active during a reading task.
- Tulving et al. (1994)
- Showed semantic and episodic memories are located in different parts of the frontal cortex.
What neurological evidence is there to support the localisation theory?
- Lobotomy still performed on extreme cases of OCD and depression.
- Dougherty et al. (2002) reported on 44 OCD patients who had undergone a cingulotomy.
- After 32 weeks = 1/3 had met successful response criteria, 14% for a partial response
= symptoms localised?
A part from brain scan evidence and neurological evidence, give a further strength of the localisation theory.
1) Case study evidence.
- Phineas Gage.
- Pole went in his chin through his head, destroying most of his frontal lobe.
- Personality said to have changed from calm and reserved to short-tempered.
What contradictory evidence is there to the localisation theory?
- Lashley’s (1950) research.
- Suggested higher cognitive processes, such as processes involved in learning, are more holistic than localised.
- Removed 10-50% of the cortex in rats that were learning a maze.
= no area proven to be important in terms of ability to learn.
What is brain plasticity?
The brain’s tendency to change and adapt (functionally and physically) as a result of experience and new learning.
What did Gopnick et al. (1999) find?
- Our synaptic connections peak at 2-3 years of age, at around 15,000.
What is synaptic pruning?
Rarely used connections are deleted, frequently used ones are strengthened.
Does plasticity occur at only given times?
- No, the brain has the ability to change throughout life.
- Connections change, or new neural connections can be formed as a result of learning and experience.
Who did research into plasticity? Describe it.
1) Maguire et al. (2000)
- found more volume of grey matter in London taxi drivers than in a matched control group.
- This area is associated with the development of spatial and navigational skills in humans.
- London cab drivers must take ‘The Knowledge’ test - longer they were in the job, the more pronounced the structural differences.
What did Mechelli et al. (2004) find?
- Larger parietal cortex in the brains of people who are bilingual than monolingual counterparts.
What is functional recovery?
Healthy areas taking over damaged/missing/destroyed areas of the brain.
What happens during recovery of the brain?
1) Doidge (2007) - secondary neural pathways are activated or ‘unmasked’ to enable normal functioning, often same way as before.
What structural changes happen in the brain during recovery?
1) Axonal sprouting = growth of new nerve endings which connect with nerve cells to form new pathways.
2) Reformation of blood vessels.
3) Recruitment of homologous (similar) areas on the opposite side of the brain to perform specific tasks.
How does research into plasticity and recovery research have practical application?
- Understanding of such processes has contributed to the field of neurorehabilitation
- Recovery after injury slows down after a number of weeks, so techniques such as movement therapy and electrical stimulation of the brain may be used to counter the deficit..
A part from practical application, give a further strength of plasticity and functional recovery of the brain.
1) Support from animal studies.
- Hubel + Wiesel (1963)
- Sewing one eye of a kitten shut and analysed brain cortical response.
- Visual cortex continued to process info from the open eye.
Give 2 evaluative limitations of plasticity and functional recovery of the brain
1) Negative plasticity.
- can have maladaptive behavioural consequences.
- Medina et al. (2007) - prolonged drug use has been shown to result in poorer cognitive functioning as well as an increased risk of dementia later in life.
- Ramachandran + Hirstein (1998) - 60-80% of amputees experience phantom limb syndrome.
2) Age and plasticity (complex)
- functional plasticity reduces with age; easier to adapt as a child due to new experiences and learning.
- Bezzola et al. (2012) - observed reduced motor cortex activity in participants aged 40-60 after 40 hours of golf training
= more efficient neural representations after training.
What is the definition of hemispheric lateralisation?
The idea that the two halves of the brain are functionally different - processes and behaviours are mainly controlled by one hemisphere.
Who did research into split-brain research?
Describe Sperry’s procedure
- Studied 11 individuals who had their corpus callosum cut to control frequent and severe epileptic seizures
= thus see independence of hemispheres and if they were specialised for certain functions.
- Devised a general procedure
(i) An image/word could be projected to a patient’s right visual field (processed by left hemisphere) and the same/different image could be projected on to the left visual field
= info can’t be shared
What were the findings of Sperry’s research?
- Could easily describe what was seen in right visual field.
- Couldn’t describe objects shown to the left visual field, sometimes reporting nothing was there.
= Language processed in the left hemisphere - so lack of ability to describe objects in the left visual field is because of the lack of language centres in the RH.
- Even though they couldn’t verbally identify what they had seen, they could understand what the object was using the RH - selecting the object accordingly.
- Would write down answers with their left hand, e.g. key and say the word ‘ring’
- RH also appeared dominant in terms of recognising faces - images from left visual field consistently picked.
Give 3 evaluative strengths of split-brain research into hemispheric lateralisation
1) Research showed lateralised brain functions.
- appears to be that the left hemisphere is more geared towards analytical and verbal tasks whilst the right one is more adept at performing spatial tasks and music.
- -> Contributed to our understanding greatly.
- -> Oversimplified? Work together? Carried out by each other?
2) Methodological strength.
- used methods that were adaptable to people who had ‘split brains’ e.g. blindfolding people to ensure one hemisphere was receiving info and another was not.
= controlled, standardised.
3) Started debate about the nature of the brain
- theoretical and philosophical debate about the nature of consciousness and communication between the hemispheres.
- e.g. Pucetti (1977) - two hemispheres so functionally different that they represent a form of duality in the brain; in a sense there’s ‘two minds’.
Give a limitation of split-brain research into hemispheric lateralisation
1) Issues with generalisation.
- split brain patients are an unusually small sample of people - 11.
- all suffered epileptic seizures in past –> unique differences?
- some suffered more disconnection of the hemispheres than others?
What are the 4 ways of studying the brain?
Describe what an fMRI does?
Detects changes in bloody oxygenation and flow that occur as a result of neural activity in specific parts of the brain
= when a brain is more active it consumes more oxygen, blood flow is directed to the active area.
Give 2 strengths of an fMRI
1) Does not rely on the used of radiation
- if administered correctly; it is almost risk-free, non-invasive and straightforward to use
2) High spatial resolution, details by millimetre providing a clear picture
Give 2 limitations of an fMRI
1) Expensive compared to others and can only capture a clear image if the person stays still.
2) Can only measure blood flow in the brain; cannot home in on activity of individual neurons
= what brain activity is being represented?
Describe what an EEG does?
- Measures electrical activity within the brain via electrodes
- Scan represents the brainwave patterns that are generated from the action of millions of neurons.
- Often used as a diagnostic tool for ‘arrythmic patterns of activity’ this may include neural abnormalities.
Give 2 strengths of an EEG
1) Proved invaluable in diagnosis of conditions such as epilepsy
- characterised by random bursts of activity, also increased our understanding into stages of sleep.
2) Extremely high temporal resolution
- can accurately detect brain activity at a resolution of a single millisecond.
Give a limitation of an EEG
1) Not useful for pinpointing the exact source of neural activity.
- does not allow researchers to distinguish between activities originating in different but adjacent locations.
Describe what an ERP is
- The brain’s physiological response to a specific sensory, cognitive, or motor event can be isolated through statistical analysis of EEG data.
Give 2 strengths of the ERP
1) ERPs derived from EEG measurements, so have excellent temporal resolution especially compared to fMRI
2) Able to identify different types of ERP and can describe the precise role of these in cognitive functioning.
Give 2 limitations of the ERP
1) Lack of standardisation in ERP methodology between different research studies = hard to confirm findings.
2) Inn order to establish pure ERP data, background noise and extraneous material must be eliminated.
Describe what a post-mortem examination is
Brain is analysed after death to determine whether certain observed behaviour during the patient’s lifetime can be linked to abnormalities in the brain.
Give a strength of post-mortem examinations
1) Vital in providing a foundation for early understanding of key processes in the brain, e.g. Broca’s/Wernicke’s area.
Give 2 limitations of post-mortem examinations
1) Causation is an issue
- observed damage may not be linked to the deficits under review
= some other trauma?
2) Ethical issues
- consent before analysis of the brain? e.g. case of HM.
What is a circadian rhythm?
A type of biological rhythm subject to a 24 hour cycle.
; changes in core body temp, sleep/wake cycle.
Describe Siffre’s study into circadian rhythms
- Deprived himself of natural light and sound, but with access to food and drink.
- He resurfaced after 2 months in Southern Alps in September 1962 believing it to be mid-August, repeated it a decade later in a Texan cave.
- His biological rhythm extended to around 25 hours; though he did fall asleep and wake up on a regular schedule.
A part from Siffre’s study, describe research into circadian rhythms.
1) Aschoff + Wever (1976) convinced participants to spend 4 weeks in a WW2 bunker deprived of light.
- One person displayed a sleep/wake cycle of 29 hours, whilst the others displayed a 24/25 circadian rhythms.
2) Folkard et al. (1985).
- 12 people lived in a cave for 3 weeks, going to bed at 11:45pm and rising at 7:45am.
- The researchers sped up the clock so an apparent 24 hour day became 22.
= only one of the participants was said to have comfortably adjusted to this reigme.
How does research into circadian rhythms have practical application?
- Better understanding of adverse consequences that can occur as a result of desynchronisation.
(i) Boivin et al. (1996) - night workers engaged in shift work experienced reduced concentration around 6 in the morning = accidents/mistakes more likely.
(ii) Knutsson (2003) - shift workers 3x more likely to develop heart disease
= from stress adjusting? poor quality sleep during the day?
How does research into circadian rhythms have practical applications to drugs?
- Cr co-ordinate basic body processes such as heart
rate, hormone levels, digestion
- Research shown certain peak times during night/day when drugs are likely to be at their most effective.
- Baraldo (2008) - guidelines developed to do with timing of drug dosing of medications including anticancer drugs.
Give 2 limitations of (research into) circadian rhythms
1) Case studies and small samples
- unrepresentative of the wider population = lack generalisation.
- Siffre observed at 60 that his internal clock ticked much more slowly than when he was younger
2) Individual differences: complicates generalisation.
- Czeisler et al. (1999) - sleep/wake cycles from 13-65 hours.
- Duffy et al. (2001) - some people display a natural preference for going to bed early and thus rising early, others prefer other way round.
; age differences in sleep/wake cycle also present.
What is an infradian rhythm?
Biological rhythms with frequency of less than one cycle in 24 hours, such as menstruation and SAD.
What is an ultradian rhythm?
Biological rhythms with a frequency of more than one cycle in 24 hours, such as the stages of sleep
Who did research into how exogenous zeitgebers may synchronise menstrual cycles? Describe it
- Stern + McClintock (1998).
- 29 women with a history of irregular periods.
- Pheromones gathered from 9 of the women at different stages via a cotton pad to the arm pit - worn for at least 8 hours a day to ensure pheromones were picked up .
- 20 others were given pads from the start of the menstrual cycle, day 2 and so on.
- 68% of women experienced changes to their cycle, closer to that of their ‘donor’.
What is SAD?
- Seasonal Affective Disorder.
- Depressive disorder brought about by seasonal onset; symptoms are triggered in winter months by shorter sunlight hours
= particular type of infradian rhythm called circannual rhythm
What hormone is SAD linked to?
- Secreted by the pineal gland during the night until there is an increase in light.
- Longer darker hours in winter months means the secretion continues for longer –> knock on serotonin production.
How long does each stage of sleep last for?
90 minute periods.
What stage of sleep cycle is REM sleep?
- Stage 5.
- Body is paralysed yet the brain activity speeds up ,resembling and awake brain = correlated with experiences of dreaming.
How does research on the menstrual cycle show its evolutionary value?
- Advantageous for females to menstruate together and thus fall pregnant together = cared for collectively.
- -> increasing chances of offspring’s survival.
- Schank (2004) challenges this.
- Huge amounts of women in menstrual synchrony may produce competition for the highest quality males.
Describe the limitation of the methodology used in menstrual synchrony studies.
- Many factors that may effect change in a cycle, including stress, change in diet, exercise etc = confouding variables.
; Appeared by chance? Can’t say for certain.
- Trevathan et al. (1993) - failed to find any evidence of menstrual synchrony.
What evidence supports distinct stages of sleep?
- Dement + Kleitman (1957) monitored sleep patterns of 9 adults.
- Activity recorded on an EEG; REM activity during sleep highly correlated with experiences with of dreaming = brain activity varied according to how vivid dreams were.
- Participants woken during dreaming reported very accurate recall of their dreams.
How does research into SAD have practical applications?
- Phototherapy, a strong light in the morning and evening; thought to reset melatonin levels in SAD sufferers.
- Eastman et al. (1998) - relieved symptoms in 60% of sufferers; placebo showed 30% increase however.
What are endogenous pacemakers?
Internal body clocks that regulate many of our biological rhythms.
What are exogenous zeitgebers?
External cues that may affect or entrain our biological rhythms, such as light.
Describe what the suprachiasmatic nucleus (SCN) is and does
- Located in hypothalamus.
- Receives info about light from the optic chiasm; continues even when our eyes are closed.
= enabling our biological clocks to adjust to changing patterns of daylight.
How did DeCoursey et al. (2000) show the influence of the SCN? Describe his study.
- Destroyed SCN connections in the brain of 30 chipmunks which were returned to their natural habitat and observed for 80 days.
- Sleep/wake cycle disappeared, significant proportion had been killed by predators
= being awake when they shouldn’t have.
How did Ralph et al. (1990) show the influence of the SCN? Describe his study.
- Bred hamsters with a 20 hour sleep/wake cycle.
- Transplanted SCN from the foetal tissue of 20 hr hamsters to brains of normal hamsters.
= cycle of normal hamsters defaulted to 20 hours.
What does the SCN pass information to?
- Passes on info on day length and light to the pineal gland.
- This is responsible for production of melatonin during the night = inducing sleep.
How can light affect endogenous pacemakers?
- Can reset the SCN.
- Influence key processes in the body such as hormone secretion.
Describe Campbell + Murphy’s (1998) study into the influence of light on the sleep/wake cycle.
- Light may be detected by skin receptors on the body even when the same info is not received by the eye.
- 15 participants woken at various times and a light pad shone on the back of their knees
= deviation of sleep/wake cycle of up to 3 hours.
= not just eyes?
How do social cues affect the sleep/wake cycle?
- Infants not often on the same sleep/wake cycle as the family.
- Usually entrained by 16 weeks.
- Adults determine mealtimes and bedtimes - not necessarily responding to feelings of hunger/fatigue.
Describe the limitation that ‘research into the SCN is that may obscure other body clocks’
-Many CRs in many organs/cells of the body called peripheral oscillators = can act independently from the SCN.
- Damiola et al. (2000) - changing feeding patterns in mice could alter circadian rhythms of cells in the liver by 12 hours
= leaving SCN unaffected.
How does research into endogenous pacemakers and exogenous zeitgebers suffer from ethical issues?
- Use of animals who came up considerable harm with subsequent risk (DeCoursey)
- Do the findings justify the ethics?
How might the influence of exogenous zeitgebers be overstated?
- Miles et al. (1977).
- Story of a young man blind from birth with a circadian rhythm of 24.9 hours.
- Despite social cues his sleep/wake cycle could not be adjusted.
- Had to take stimulants and sedatives.
- Studies of individuals in Arctic region show normal sleep patterns despite prolonged exposure to light.
How is there methodological issues in studies of endogenous pacemakers and exogenous zeitgebers?
- Campbell + Murphy’s study yet to be replicated.
- May have been some limited light exposure to the participants’ eyes = confouding variable.
- Eliminating light zeitgeber does not give us insight into other zeitgebers that influence the sleep/wake cycle.