2.2 biopsychology

Question 1

central nervous system

Answer 1

the CNS consists of the brain and spinal cord. it controls the behaviour and regulation of the body’s physiological processes.

Question 2

brain

Answer 2

the brain RECEIVES info from the sensory receptors (eyes, ears, skin etc) and SENDS messages to the muscles and glands of the body in response.

Question 3

4 areas of the brain

Answer 3

1. cerebrum: largest part of the brain. has 4 lobes split into 2 halves (the right and left hemisphere)
2. cerebellum: responsible for motor skills, balance and coordinating the muscles to allow precise movements
3. diencephalon: contains the thalamus (regulates consciousness, sleep and alertness) and the hypothalamus (regulates BTSH: body temperature, thirst, stress response and hunger)
4. brain stem: regulates breathing and heart rate

Question 4

spinal cord: function, connections and damage

Answer 4

the spinal cord is used to relay information between the brain and the rest of the body. it is connected to different parts of the body by pairs of spinal nerves, which connect to specific muscles and glands.

it allows the brain to monitor and regulate bodily processes, like digestion, breathing and to co-ordinate voluntary movement

if the spinal cord is damaged, body areas connected to it by nerves below the damage will be cut off and stop functioning.

Question 5

peripheral nervous system

Answer 5

the PNS is the nervous system throughout the rest of the body (not the brain or spinal cord). it transmits messages via neurons (nerve cells) to and from the CNS. it has 2 divisions: somatic and autonomic nervous system

Question 6

somatic nervous system

Answer 6

• controls voluntary movements and is under conscious control.
• it connects the senses with the CNS and has sensory pathways AND motor pathways.
• controls skeletal muscles but is controlled by the motor cortex.

Question 7

autonomic nervous system

Answer 7

• ANS controls involuntary movement, not under conscious control
• ONLY has motor pathways
• controls smooth muscles + the internal organs and glands of the body but is controlled by the brain stem

> has the sympathetic and parasympathetic nervous system

Question 8

sympathetic vs parasympathetic nervous system

Answer 8

SYMPATHETIC is activated when a person is stressed: heart rate + breathing increase, digestion stops, salivation reduces, pupils dilate, flow of blood is diverted from the surface on the skin (fight or flight response)

PARASYMPATHETIC is activated when the body relaxes and conserves energy: opposite to symp.

Question 9

neurons

Answer 9

specialised nerve cells that move electrical impulses to and from the CNS

Question 10

structure of a neuron

Answer 10

1. cell body: control centre of the neuron
2. nucleus: contains genetic material
3. dendrites: receives an electrical impulse (action potential) from other neurons/sensory receptors (e.g. eyes, ears, tongue and skin)
4. axon: long fibre that carries the electrical impulse from the cell body to the axon terminal
5. myelin sheath: insulating layer that protects the axon and speeds up the transmission of the electrical impulse
6. schwann cells: make up the myelin sheath
7. nodes of ranvier: gaps in the myelin sheath that speed up the electrical impulse along the axon

Question 11

sensory neuron

Answer 11

SN are found in the sensory receptors.

they convert information from sensory receptors into electrical impulses, then carries these to the CNS (spinal cord and brain) via the PNS.

when they reach the brain they are converted into sensations (heat, pain etc) for the body to react to appropriately. some sensory impulses terminate at the spinal cord. this allows reflexes to occur quickly without the delay of waiting for the brain to respond

the cell body is on the axon rather than in the dendrites (in the middle), and its shorter than a motor neurone

Question 12

motor neuron

Answer 12

they carry information from the CNS to the effectors. MN send electrical impulses via long axons to the glands and muscles (effectors) so they can affect function.

when motor neurons are stimulated, they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement.

MN are located in the CNS, but have long axons that project outside of it.

Question 13

relay neuron

Answer 13

RN are found in the CNS.

they connect sensory & motor neurons so that they can communicate with one another. during a reflex arc (e.g. you put your hand on a hot hob) the relay neurons in the spinal cord are involved in an analysis of the sensation and deciding how to respond (e.g. to lift your hand) without waiting for the brain to process the pain.

it’s axon is smaller than the other two, so it doesn’t need a myelin sheath

Question 14

synaptic transmission 1: neurones

Answer 14

neurons transmit electrical impulses (action potentials) between the pre-synaptic neuron (the one transferring) and the post-synaptic neuron (the one receiving)

Question 15

synaptic transmission 2: exocytosis

Answer 15

when the action potential reaches the pre-synaptic terminal, it triggers exocytosis. this is the release of neurotransmitters from sacs on the pre-synaptic membrane (vesicles)

the released neurotransmitter will diffuse across the synaptic cleft (the physical gap between the pre-synaptic membrane and post-synaptic membrane) where it binds to specialised post-synaptic receptor sites.

Question 16

synaptic transmission 3: reuptake

Answer 16

synaptic transmission only takes a fraction of a second, and the effects are terminated by a process called re-uptake.

this is when the neurotransmitter is taken back by the vesicles on the pre-synaptic neuron where they are stored for later release.

the quicker the neurotransmitter is taken back the shorter the effects

Question 17

synaptic transmission 4: excitatory and inhibitory neurotransmitters

Answer 17

neurotransmitters can be excitatory or inhibitory. most can be both, but GABA is solely inhibitory.

excitatory neurotransmitters cause an electrical charge in the membrane of the post-synaptic neuron. this results in excitatory post-synaptic potential (the post-synaptic neuron is MORE likely to fire an impulse).

inhibitory neurotransmitters cause an inhibitory post-synaptic potential (the post-synaptic neuron is LESS likely to fire an impulse)

Question 18

synaptic transmission 5: summation

Answer 18

a neuron can receive both EPSPs and IPSPs at the same time.

the likelihood that the neuron will fire an impulse is determined by adding up the excitatory and the inhibitory synaptic input. the net result of this calculation (summation) determines whether or not the neuron will fire an impulse.

if the net effect is inhibitory the neuron will not fire, and excitatory will result in neuron fire

Question 19

direction of synaptic transmission

Answer 19

information can only travel in one direction at a synapse.

the vesicles containing neurotransmitters are ONLY present on the pre-synaptic membrane. the receptors for the neurotransmitters are ONLY present on the post-synaptic membrane.

it is the binding of the neurotransmitter to the receptor that enables the information to be transmitted to the next neuron.

diffusion of the neurotransmitters means they can only go from high to low concentration, so can only travel from the pre to the post-synaptic membrane

Question 20

psychoactive drugs

Answer 20

psychoactive drugs (like SSRI’s) are medication that affects brain function to alter perception, mood or behaviour.

they work by affecting (increasing or inhibiting) the transmission of neurotransmitters across the synapse

Question 21

pain medication

Answer 21

some pain medications mimic the effect of inhibitory neurotransmitters. when an inhibitory neurotransmitter binds to the post-synaptic receptors it makes the post-synaptic neuron less likely to fire.

if they are higher than excitatory neurotransmitters, inhibitory can inhibit an action potential from occurring (summation). pain medications would decrease overall activity and reducing brain activity may lead to less pain

Question 22

endocrine system: glands

Answer 22

the endocrine system provides a chemical system of communication in the body via the bloodstream.

endocrine glands produce and secrete hormones into the bloodstream which are required to regulate many bodily functions. the major glands are the pituitary and adrenal glands. each gland produces different hormones that regulate activity of organs/tissues in the body

Question 23

endocrine system: hormones

Answer 23

hormones come into contact with most cells in the body, but they only affect a limited number of cells (target cells). target cells respond to a particular hormone because they have receptors for that hormone. when enough receptor sites are simulated by that hormone there is a physiological reaction

Question 24

pituitary gland

Answer 24

the pituitary gland is located in the brain. it produces hormones whose primary function is to influence the release of other hormones from other glands in the body. the pituitary gland is controlled by the hypothalamus (region of the brain just above the pituitary gland).

it has two divisions: the anterior pituitary gland and the posterior pituitary gland

Question 25

anterior and posterior pituitary glands

Answer 25

anterior: releases the hormone called ACTH which regulates levels of the hormone cortisol

posterior: responsible for releasing the hormone oxytocin which is crucial for infant/mother bonding

Question 26

hypothalamus

Answer 26

the hypothalamus receives information from many sources about the basic functions of the body and then sends a signal to the pituitary gland in the form of a releasing hormone.

this causes the pituitary gland to send a stimulating hormone into the bloodstream to tell the target gland to release its hormone.

as levels of this hormone rise in the bloodstream the hypothalamus shuts down production of the releasing hormone and the pituitary gland shuts down the secretion of the stimulating hormone.

Question 27

adrenal glands

Answer 27

2 situated on top of the kidneys. each adrenal gland is made up of two distinct parts: adrenal cortex and medulla

Question 28

adrenal cortex

Answer 28

the outer section of the adrenal gland is called the adrenal cortex.

it produces the hormone cortisol which is produced in high amounts when someone is experiencing chronic stress. cortisol is also responsible for the cardiovascular system eg. it will increase blood pressure and causes blood vessels to constrict

Question 29

adrenal medulla

Answer 29

the inner section of the adrenal gland is called the adrenal medulla.

it produces adrenaline, the hormone that is needed for the fight or flight response. adrenaline is activated when someone is acutely stressed. it increases heart rate, dilates pupils and stops digestion

Question 30

sympathomedullary pathway

Answer 30

the sympathetic nervous system is triggered by the hypothalamus. the hypothalamus also sends a signal to the adrenal medulla. the adrenal medulla releases the hormone adrenaline into the bloodstream.

Question 31

adrenaline

Answer 31

• will increase heart rate, constrict blood vessels, increase rate of blood flow, raise blood pressure, divert blood away from the skin, kidneys and digestive system, increase blood supply to the brain and skeletal muscles and increase respiration and sweating
• all prepares the body for fight or flight by increasing blood supply and therefore oxygen to skeletal muscles for physical action and the brain for rapid response planning

Question 32

parasympathetic nervous system

Answer 32

when the threat has passed, the parasympathetic nervous system dampens down the stress response. slows down the heartbeat, reduces blood pressure, digestion restarts

Question 33

strengths of fight or flight explanation

Answer 33

+ the fight or flight response makes sense from an evolutionary psychology point of view because it would have helped an individual to survive by fighting or fleeing a threat

+ studies supports the claim that adrenaline is essential in preparing the body for stress. people who have malfunctioning adrenal glands do not have a normal fight or flight response to stress.

Question 34

weakness of fight or flight explanation: gray (1988)

Answer 34

• gray (1988) states that the first reaction to stress is not fight or flight, but freeze. person stops, looks and listens and is hyper vigilant to danger

Question 35

weakness of fight or flight explanation: taylor (2000)

Answer 35

• taylor (2000) found that females tend and befriend in times of stress. protection of offspring (tend) and seeking out social groups for mutual defence (befriend). women have the hormone oxytocin, which means they are more likely to stay and protect their offspring.

Question 36

weakness of fight or flight explanation: von dawans (2012)

Answer 36

• von dawans (2012) found that even males tend and befriend. eg. during 9/11 terrorist attacks, both males and females showed tend and befriend as they tried to contact loved ones and help one another

Question 37

4 lobes of the brain and where they are

Answer 37

L-R

(1) frontal, (2) parietal, (3) occipital

(4 bottom) temporal

Question 38

localisation of function

Answer 38

the idea that functions have specific locations within the brain. some functions are more localised than others, like the motor and somatosensory functions (which are highly localised to particular areas of the cortex).

other functions are more widely distributed like the language centres. these use several parts of the brain, though some components like speech production may be more localised (broca’s area)

Question 39

visual centres

Answer 39

visual processing starts in the retina where light enters and strikes the photoreceptors. nerve impulses from the retina are transmitted to the brain via the optic nerve.

majority terminate in the thalamus which acts as a relay station, passing information onto the visual cortex

the visual cortex processes information like colour and shape. it’s in the OCCIPITAL lobe of BOTH brain hemispheres.

Question 40

auditory centres

Answer 40

the auditory pathway begins in the cochlea in the inner ear, where sound waves are converted to nerve impulses.

they travel via the auditory nerve to the auditory cortex. basic decoding occurs in the brain stem and the thalamus carries out further processing before impulses reach the auditory cortex

the auditory cortex processes information such as pitch and volume, and is located in the TEMPORAL lobe in BOTH hemispheres of the brain

Question 41

motor cortex

Answer 41

it is responsible for voluntary movements.

different parts of the motor cortex control different parts of the body. these areas are arranged logically next to one another.

damage to this area can cause a loss of muscle function/paralysis in one or both sides of the body (depending on which hemisphere/hemispheres have been affected).

it’s located in the FRONTAL lobe of BOTH brain hemispheres

Question 42

somatosensory cortex

Answer 42

it’s responsible for processing sensations such as pain and pressure. it’s located in PARIETAL lobe in BOTH hemispheres

Question 43

broca’s area

Answer 43

paul broca treated patients who had difficult PRODUCING speech. he found that they had lesions to the LEFT hemisphere of the FRONTAL lobe.

damage to broca’s area causes expressive aphasia. this disorder affects language production (bad) but not understanding (good). speech lacks fluency and patients have difficulty with certain words like ‘it’ and ‘the’

Question 44

wernicke’s area

Answer 44

carl wernicke investigated patients with issues in PROCESSING speech. he found that they had lesions to the LEFT hemisphere of the TEMPORAL lobe.

damage to wernicke’s area caused receptive aphasia. this disorder affects the ability to understand language (bad) but not produce language (good).

wernicke’s and broca’s areas are connected by a neural loop.

Question 45

weakness of localisation of function: localisation varies

Answer 45

• some functions are more localised than others. motor and somatosensory functions are highly localised to specific areas of the cortex, but higher functions like personality and consciousness are much more widely distributed. functions like language are too complex to be assigned to just one area, and instead involve networks of brain regions.

Question 46

weakness of localisation of function: lashley (1930)

Answer 46

• lashley (1930) devised ‘equipoteniality’ theory, which states that higher mental functions are not localised.

the theory also claims that intact areas of the cortex take over responsibility for a specific cognitive function following injury to the area normally responsible.

Question 47

weakness of localisation of function: dronkers (2007)

Answer 47

• dronkers et al (2007) re-examined the preserved brains of two of broca’s patients. MRI scans found that several areas of the brain had been damaged.

lesions to the broca’s area cause temporary speech disruption: they do not usually result in severe disruption of language. language is more widely distributed.

Question 48

weakness of localisation of function: dejerine (1892)

Answer 48

• it might be that how brain areas communicate with each other is more important than specific brain regions. dejerine (1892) reported a patient who could not read because of damage BETWEEN the visual cortex and wernicke’s area.

Question 49

weakness of localisation of function: bavelier (1997)

Answer 49

• bavelier et al (1997) found that there are individual differences in which brain areas are responsible for certain functions.

they found that different brain areas are activated when a person is engaged in silent reading. they observed activity in the right temporal lobe, left frontal lobe and occipital lobe. this means that the function of silent reading does not have a specific location within the brain.

Question 50

hemispheric lateralisation

Answer 50

certain functions are principally governed by one side of the brain

Question 51

left hemisphere

Answer 51

research has demonstrated that language centres are mostly lateralised to the left hemisphere.

the broca’s area was thought to be responsible for the production of speech, however, this is now thought to involve a wider network. damage to the broca’s area leads to expressive aphasia.

the wernicke’s area is considered to play a vital role in understanding language/interpreting speech. damage leads to receptive aphasia.

Question 52

right hemisphere

Answer 52

the right hemisphere is responsible for the left side of the body (eg. left sided paralysis means there is lateralised damage to the left hemisphere).

the right hemisphere is dominant for visuo-spatial functions and facial recognition.

Question 53

corpus callosum

Answer 53

the two hemispheres are connected by a bundle of nerve fibres known as the corpus callosum which enables communication of information between the two hemispheres. many researchers suggest that the two hemispheres work together to form most tasks as part of a highly integrated system

Question 54

strength of hemispheric lateralisation: rogers (2004)

Answer 54

+ it makes sense from an evolutionary perspective - it increases neural processing capacity, which is adaptive.

by using one hemisphere to engage in a particular task it leaves the other hemisphere free to engage in another function.

rogers et al. (2004) found that hemispheric lateralisation in chickens is associated with an ability to perform two tasks simultaneously (finding food and being vigilant for predators)

Question 55

strength of hemispheric lateralisation: global aphasia

Answer 55

+ patients who have extensive damage to their left hemisphere can experience global aphasia (loss of speech production and speech comprehension). this suggests that language is lateralised to the left hemisphere

Question 56

weakness of hemispheric lateralisation: szaflarski (2006)

Answer 56

• lateralisation patterns shift with age. szaflarski (2006) found that most tasks were generally less lateralised in healthy adults

Question 57

weakness of hemispheric lateralisation: JW (turk 2002)

Answer 57

• JW (a split brained patient) developed the capacity to speak using his right hemisphere, with the result that they could speak about information presented in either the left or the right visual field. although, he was more fluent if information was presented in the left. it would appear that language is not lateralised entirely to the left hemisphere (turk et al. 2002).

Question 58

weakness of hemispheric lateralisation: EB (damelli 2013)

Answer 58

if one hemisphere is damaged, undamaged regions on the opposite hemisphere can compensate.

danelli (2013) reported the case of EB, a 17-year-old italian boy who had virtually his entire left hemisphere removed at the age of 2 due to a huge benign tumour

EB’s language appeared almost normal in everyday life in terms of vocabulary and grammar, but systematic testing revealed subtle grammatical problems as well as poorer than normal scores on picture naming and reading of loan words (words adopted from another language e.g. café).

language function can be largely preserved after removal of the left hemisphere in childhood, but the right hemisphere cannot provide, by itself, a perfect mastery of each component of language

Question 59

split brain research

Answer 59

surgeons have cut corpus callosum in order to prevent violent electrical activity caused by epileptic seizures crossing from one hemisphere to the other in the past - patients are called ‘split brain patients’

Question 60

sperry and gazzaniga (1968)

Answer 60

investigated split-brained patients.

info from left visual field goes into the right hemisphere + vice versa. in split-brain patients corpus callosum has been severed, meaning there is no way for the info presented to travel from one hemisphere to the other

Question 61

sperry and gazzaniga (1968): procedure

Answer 61

patients were asked to stare at a dot in the centre of a screen and then information was presented in either the left or right visual field.

they were then asked to make responses with either their left hand (right hemisphere), right hand (left hemisphere), or verbally (left hemisphere) without being able to see what their hands were doing

Question 62

sperry and gazzaniga (1968): findings

Answer 62

patients may be flashed an image of a dog in their right visual field and then asked what they have seen. they will be able to answer ‘dog’ because the info will have gone into their left hemisphere where the language centres are

if a picture of a cat is shown in their left visual field and they are asked what they have seen they will not be able to say because the info has gone into their right hemisphere, which has no language centres

however, they can draw a picture of a cat with their left hand because the right hemisphere controls visio-spatial and facial recognition, and the left hand

Question 63

two strengths of split-brain research

Answer 63

+ experiments on split-brain patients are highly controlled and scientific. split-brain research has enabled discoveries of hemispheric lateralisation

+ the comparison groups for split brained patients were seen as not valid as the control groups didn’t include those with a history of seizures

Question 64

three weaknesses of split brain research

Answer 64

• split-brain patients have often had drug therapy for their epilepsy for much longer than others, which may affect the way in which their brain works. this means the findings of split-brain research cannot be generalised to the target population
• many studies using split-brain patients have as few as three participants, making it hard for results to be generalised to the target population
• data from this research is very artificial. in the real world a severed corpus callosum can be compensated for by the unrestricted use of both visual fields. this means the research lacks ecological validity.

Question 65

brain plasticity

Answer 65

refers to brain’s ability to change and adapt as a result of experience. plasticity allows the brain to cope better with the indirect effects of brain damage e.g. swelling or haemorrhage following a road accident, or the damage resulting from inadequate blood supply after a stroke

Question 66

plasticity: life experience

Answer 66

nerve pathways that are used frequently develop stronger connections, those that are rarely used eventually die. by developing new connections and reducing weak ones the brain is able to adapt to a changing environment.

however, there is also a decline in cognitive functioning with age attributed to these changes boyke et al. (2008) taught 60-year-olds a new skill (juggling), and this increased grey matter in the visual cortex

Question 67

plasticity: video games

Answer 67

kuhn et al. (2014) compared a control group to a group who had been given video game training for at least 30 minutes a day for two months on the game ‘Super Mario’

he found that playing video games caused a significant increase in grey matter in the visual cortex, hippocampus, and cerebellum

playing video games results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory, and motor performance

Question 68

plasticity: meditation

Answer 68

davidson et al. (2004) compared eight practitioners of tibetan meditation with ten students who had no previous meditation experience

an EEG picked up greater gamma wave activity in the monks, even before they started meditating. gamma waves coordinate neural activity

Question 69

two strengths of plasticity

Answer 69

+ kempermann et al. (1998) found far more new neurons in the brains of rats in complex environments compared to those housed in basic cages. this increase in neurons was most prominent in the hippocampus, which is involved in the forming of new long-term memories and the ability to navigate.

+ maguire et al. (2000) measured grey matter in the brains of london taxi drivers using an MRI scan. the hippocampus in taxi drivers was significantly larger than a control group and this was positively correlated with the amount of time they had spent as a taxi driver (the extent of their life experience)

Question 70

functional recovery

Answer 70

this is a form of plasticity. following damage by trauma, the brain can redistribute or transfer functions usually performed by a damaged area to other, undamaged areas.

recovery from trauma is more likely when the brain is still maturing (elbert et al 2001). however, the brain is capable of plasticity and functional recovery at any age. studies have suggested women recover more quickly than men

Question 71

neural reorganisation and regeneration

Answer 71

neural reorganisation = the transfer of functions from damaged areas of the brain to undamaged ones

neural regeneration = growth of new neurons and/or connections (axons and dendrites) to compensate for damaged areas. axon sprouting is part of neural regeneration - new nerve endings grow and connect with other undamaged nerve cells to form new neural pathways

Question 72

spontaneous recovery

Answer 72

spontaneous recovery from brain injury tends to slow down after several weeks so physiotherapy may be required to maintain improvements in functioning.

techniques can include movement therapy and electrical stimulation of the brain to counter deficits in motor and cognitive functioning that can be experienced following a stroke

Question 73

two strengths of functional recovery

Answer 73

+ phantom limb syndrome (PLS) can be used as evidence of neural reorganisation - PLS is the continued experience of sensation in a missing limb, as if it were still there. these sensations are often unpleasant and even painful. PLS is thought to be caused by neural reorganisation in the somatosensory cortex that occurs as a result of limb loss

+ hubel and torten wisel (1963) sewed one eye of a kitten shut and analysed the brain’s cortical response. they found that the visual cortex for the shut eye was not idle (as was predicted) it continued to process information from the open eye. this is further evidence that brain areas can reorganise themselves and adapt their functions.

Question 74

post mortem examinations

Answer 74

psychologists may study a person who displays an interesting behaviour while they are alive. when they die, psychologists look for abnormalities in the brain that explain their behaviour. post-mortem studies have found a link between brain abnormalities and psychiatric disorders. eg. there is evidence of reduced glial cells in the frontal lobe of patients with depression.

Question 75

evaluation of post mortem exams

Answer 75

+ post mortem studies allow for more detailed examinations of anatomical and neurochemical aspects of the brain than would be possible with other methods of studying the brain. they have enabled researchers to examine deeper regions like the hippocampus/hypothalamus

• studies using post-mortem may lack validity because people die in a variety of circumstances at varying stages of disease. the length of time between death/post-mortem and drug treatments can all affect the brain
• post mortem studies have small sample sizes (special permission needs to be granted). the sample therefore cannot be said to be representative of the target population, so it is problematic to generalise the findings to the wider population

Question 76

functional magnetic resonance imaging (fMRI)

Answer 76

fMRI provides an INDIRECT measure of neural activity.

it uses magnetic fields and radio waves to monitor blood flow in the brain. it measures the change in the energy released by haemoglobin, reflecting activity of the brain (oxygen consumption) to give a moving picture of the brain.

activity in regions of interest can be compared during a base line task and during a specific activity

Question 77

two strengths of fMRI’s

Answer 77

+ fMRIs captures dynamic brain activity as opposed to a post-mortem examination which purely show the physiology of the brain.

+ fMRIs have good spatial resolution (refers to the smallest feature that a measurement can detect).

Question 78

two weaknesses of fMRI’s

Answer 78

• interpretation of fMRI is complex and is affected by poor temporal resolution (resolution of a measurement with respect to time), biased interpretation, and by the base line task used.
• fMRI research is expensive leading to reduced sample sizes which negatively impact the validity of the research

Question 78

electroencephalogram (EEG)

Answer 78

EEG’s DIRECTLY measure GENERAL neural activity in the brain, usually linked to states such as sleep and arousal.

electrodes are placed on the scalp and detect neuronal activity directly below where they are placed. differing numbers of electrodes can be used depending on focus of the research.

when electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG pattern.

EEG patterns of patients with epilepsy show spikes of electrical activity. EEG patterns of those with brain injury show a slowing of electrical activity.

Question 78

three strength’s of EEG

Answer 78

+ an EEG is useful in clinical diagnosis. for example, it can record the neural activity associated with epilepsy so that doctors can confirm the person is experiencing seizures.

+ EEGs are cheaper than an fMRI so can be used more widely in research.

+ temporal resolution as they can be graphed

Question 79

one weakness of EEG’s

Answer 79

• EEGs have poor spatial resolution (refers to the smallest feature that a measurement can detect).

Question 80

event-related potentials

Answer 80

electrodes are placed on the scalp and DIRECTLY measure neural activity (below where they are placed) in response to a SPECIFIC stimulus introduced by the researcher.

event-related potentials are difficult to pick out from all the other electrical activity being generated within the brain. to establish a specific response to a target stimulus requires many presentations of this stimulus and the responses are then averaged together.

any extraneous neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will.

Question 81

three strengths of ERPs

Answer 81

+ ERPs can measure the processing of a stimulus even in the absence of a behavioural response. therefore it is possible to measure ‘covertly’ the processing of a stimulus.

+ ERPs are cheaper than an fMRI so can be used more widely in research.

+ ERPs have good temporal resolution unlike fMRIs (resolution of a measurement with respect to time)

Question 82

two weaknesses of ERPs

Answer 82

• ERPs have poor spatial resolution unlike fMRIs (refers to the smallest feature that a measurement can detect).
• only sufficiently strong voltage changes generated across the scalp are recordable. important electrical activity occurring deeper in the brain is not recorded. the generation of ERPs tends to be restricted to the neocortex.

Question 83

biological rhythms

Answer 83

biological rhythms are cyclical changes in physiological systems. they evolved because the environments in which organisms live have cyclical changes e.g. day/night, summer/winter etc. the three types of biological rhythms are circadian, infradian and ultradian

Question 84

circadian rhythms

Answer 84

any cycle that lasts 24 hours. nearly all organisms possess a biological representation of the 24 hour day. these optimise an organism’s physiology and behaviour to best meet the varying demands of the day/night cycle.

Question 85

SCN

Answer 85

suprachiasmatic nuclei

circadian rhythms are driven by the SCN in the hypothalamus. this pacemaker (controls the rate at which something occurs) must constantly be reset so that our bodies are in synchrony with the outside world.

natural light provides the input to this system, setting the SCN to the correct time in a process called photoentrainment. the SCN then uses this information to coordinate activity of circadian rhythms throughout the body.

Question 86

sleep-wake cycle: light

Answer 86

light and darkness are the external signals that determine when we feel the need to sleep and when we wake up. circadian rhythms keep us awake as long as there is daylight, prompting us to sleep as it becomes dark.

Question 87

sleep-wake cycle: melatonin

Answer 87

release of melatonin from the pineal gland is at its peak during the hours of darkness. melatonin induces sleep by inhibiting the neural mechanisms that promote wakefulness. light supresses the production of melatonin.

Question 88

sleep-wake cycle: homeostasis

Answer 88

sleep and wakefulness are also under homeostatic control. when we have been awake for a long time, homeostasis signals that we need more sleep because of the amount of energy used up during wakefulness. this homeostatic drive for sleep increases gradually throughout the day, reaching its maximum in the late evening.

the circadian rhythm dips and rises at different times of the day so that the strongest sleep drives occur between 2:00-4:00am and 1:00-3:00pm

the homeostatic system tends to make us sleepier the longer we have been awake regardless of whether it is night or day. the internal circadian rhythm will maintain a cycle of 24-25 hours, even without natural light.

Question 89

strength of circadian rhythms: practical application

Answer 89

+ one practical application of circadian rhythms is chronotherapeutics.

the time that patients take medication is very important for treatment success. it is essential that the right concentration of drug is released in the target area of the body at the time the drug is most needed. eg. the risk of heart attack is greatest during the early morning hours after waking.

medications have been developed that are taken before the person goes to sleep but are not released until the vulnerable time of 6:00 am.

Question 90

weakness of circadian rhythms: cziesler (1999)

Answer 90

• research on circadian rhythms has not isolated people from artificial light, because it was believed only natural light affected circadian rhythms. however, more recent research suggests this might not be true.

cziesler et al. (1999) altered participant’s circadian rhythms down to 22 hours and up to 28 hours by using artificial light alone.

Question 91

weakness of circadian rhythms: individual differences

Answer 91

• the length of circadian rhythms. one research study found that cycles can vary from 13 to 165 hours (czeisler et al, 1999).
• when they reach their peak. ‘morning people’ prefer to rise early and go to bed early whereas ‘evening people’ prefer to rise late.

Question 92

weakness of circadian rhythms: arctic regions

Answer 92

individuals who live in artic regions, where the sun does not set in the summer months, show normal sleeping patterns despite the prolonged exposure to light.

this suggests that there are occasions where the exogenous zeitgeber of light may have very little bearing on our internal biological rhythms.

Question 93

ultradian rhythms: sleep stages

Answer 93

span a period of less than 24 hours eg. the five sleep stages. human sleep follows a pattern alternating between rapid eye movement (REM) sleep (stage five) and non-rapid eye movement (NREM) sleep (stages one-four). the cycle repeats itself every 90 minutes.

Question 94

ultradian rhythms: EEG patterns

Answer 94

each stage shows a distinct EEG pattern. as the person enters deep sleep, their brainwaves slow and their breathing and heart rate decreases. during REM, the EEG pattern resembles that of an awake person. it is during this stage that dreaming occurs.

Question 95

ultradian rhythms: 90 minute concentration

Answer 95

kleitman (1969) referred to the 90 minute cycle found during sleep as the ‘basic rest activity cycle’ (BRAC).

he suggested that this 90 minute cycle continues when we are awake. during the day, rather than moving through the sleep stages, we move progressively from a state of alertness into a state of physiological fatigue.

studies suggest that the human mind can focus for about 90 minutes, and towards the end of those 90 minutes the body begins to run out of resources, resulting in loss of concentration, fatigue and hunger.

Question 96

strength of ultradian rhythms: ericsson et al (2006)

Answer 96

+ ericsson et al. (2006) found support for the ultradian rhythms. they studied a group of elite violinists and found that among this group practise sessions were limited to 90 minutes at a time. they frequently napped to recover from practise, with the best violinists napping more. the same pattern was found among athletics, chess players and writers - fits with the BRAC.

Question 97

weakness of ultradian rhythms: tucker (2007)

Answer 97

• tucker et al. (2007) suggests that there are individual differences in ultradian rhythms which are biologically determined, and maybe even genetic. participants were studied over 11 consecutive days and nights in a lab. the researchers assessed sleep duration, time taken to fall asleep and the amount of time in each sleep stage. they found differences in all of these characteristics.

Question 98

infradian rhythms: menstrual cycle

Answer 98

infradian rhythms span a period of longer than 24 hours - weeks, months or even a year. eg. menstrual cycle lasts for about a month. there are considerable variations in the length of this cycle, with some women experiencing a 23 day cycle and others a 36 day cycle (refinetti, 2006). the average is 28 days.

Question 99

infradian rhythms: hormones

Answer 99

hormones regulate the menstrual cycle. ovulation occurs roughly halfway through the menstrual cycle, when oestrogen levels are at their peak, and usually lasts for 16-32 hours. after ovulation, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus

Question 100

strength of infradian rhythms: penton-voak (1999)

Answer 100

+ infradian rhythms can affect behaviour. penton-voak (1999) found that women express a preference for feminised male faces when choosing a partner for a long-term relationship. but they showed a preference for masculinised faces during ovulation.

Question 101

weakness of infradian rhythms: pheromones

Answer 101

• menstrual cycle is not only governed by infradian rhythms. when several women of childbearing age live together and do not take oral contraceptives, their menstrual cycles synchronise.

in one study samples of sweat were collected from one group of women and rubbed onto the upper lip of another group of women, their menstrual cycles became synchronised. this suggests that the synchronisation is affected by pheromones (pheromones are a chemical substance produced and released into the environment by an animal which affects the behaviour of others of the same species).

Question 102

regulation of biological rhythms

Answer 102

our internal biological rhythms must be finely tuned in order to stay in keeping with the outside world. in order to achieve this we have endogenous pacemakers (internal biological rhythms) and exogenous zeitgebers (external cues/factors e.g. light) which reset our biological rhythms every day.

Question 103

endogenous pacemakers

Answer 103

the most important endogenous pacemaker is the suprachiasmatic nuclei (SCN). this a tiny cluster of nerve cells in the hypothalamus. the SCN plays an important role in generating circadian rhythms. it acts as the master clock, linking other brain regions that control sleep and arousal, and controlling all other biological clocks throughout the body.

Question 104

endogenous pacemaker: SCN

Answer 104

neurons within the SCN synchronise with each other, so that their target neurons in sites elsewhere in the body receive time-coordinated signals. these peripheral clocks can maintain a circadian rhythm, but not for very long, which is why they are controlled by the SCN.

this is possible because of the SCN’s built in circadian rhythm, which only needs resetting when external light levels change. the SCN receives information about light levels through the optic nerve. if our biological clock is running slow then morning light shifts the clock.

Question 105

endogenous pacemaker: SCN to melatonin

Answer 105

the SCN also regulates the manufacture and secretion of melatonin in the pineal gland via the interconnecting neural pathway. the SCN sends a signal to the pineal gland, directing it to increase production and secretion of the hormone melatonin at night and to decrease it as light levels increase in the morning. melatonin induces sleep by inhibiting the brain mechanisms that promote wakefulness.

Question 106

evaluation of endogenous pacemakers: folkard (1996)

Answer 106

+ folkard (1996) studied a university student, kate aldcroft, who spent 25 days in a lab. she had no access to the exogenous zeitgebers of light to reset the SCN. but at the end of 25 days her core temperature rhythm was still at 24 hours. this indicates that we DO NOT need the exogenous zeitgebers of light to maintain our internal biological rhythms.

• kate’s sleep-wake cycle extended to 30 hours, with periods of sleep as long as 16 hours. this suggests that we DO need the exogenous zeitgebers of light to maintain our internal biological rhythms.

Question 107

exogenous zeitgebers

Answer 107

refers to anything whose origins are outside of the organism. they are environmental events that are responsible for maintaining the biological clock of an organism. the most important zeitgebers for most animals is light.

Question 108

exogenous zeitgebers: synchrony

Answer 108

when people move to a night shift or travel to a country with a different time zone their endogenous pacemakers try to impose their inbuilt rhythm of sleep (circadian rhythm), but this is now out of synchrony with the exogenous zeitgeber of light. out of sync biological rhythms lead to disrupted sleep patterns, increased anxiety and decreased alertness and vigilance.

Question 109

exogenous zeitgebers: SCN

Answer 109

receptors in the SCN are sensitive to changes in light levels during the day and use this information to synchronise the activity of the body’s organs and glands. light resets the internal biological clock each day, keeping it on a 24-hour cycle. a protein in the retina of the eye called melanopsin, which is sensitive to natural light, is critical in this system.

Question 110

strength of exogenous zeitgebers: blind people

Answer 110

+ the vast majority of blind people who still have light perception have normal circadian rhythms. blind people without light perception show abnormal circadian rhythms. this shows the vital role that the exogenous zeitgeber of light levels play in maintaining our internal biological rhythms.

Question 111

strength of exogenous zeitgebers: bright light flight

Answer 111

+ burgess et al. (2003) found that exposure to bright light prior to an east-west flight decreased the time needed to adjust circadian rhythms to local time.

Question 112

weakness of exogenous zeitgebers: arctic regions

Answer 112

• studies of individuals who live in artic regions, where the sun does not set in the summer months, show normal sleeping patterns despite the prolonged exposure to light. this suggests that there are occasions where the exogenous zeitgeber of light may have very little bearing on our internal biological rhythms.