new one

Question 1

The two roles of the human nervous system

Answer 1

To collect, process and respond to information in the environment
to co-ordinate the working of different organs and cells in the body

Question 2

the two subsystems of the nervous system

Answer 2

peripheral nervous system
central nervous system

Question 3

The divisions of the peripheral nervous system

Answer 3

autonomic nervous system
somatic nervous system

Question 4

The autonomic nervous system function

Answer 4

governs all vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
Split into the sympathetic nervous system and the parasympathetic nervous system

Question 5

The parts of the central nervous system

Answer 5

The brain: centre of all conscious awareness, the outer layer is called the cerebral cortex and is divided into two hemispheres
The spinal cord: an extension of the brain, responsible for reflex actions

Question 6

The peripheral nervous system

Answer 6

sends information to the CNS from the outside world and transmits messages from the CNS to muscles and glands

Question 7

The central nervous system

Answer 7

is the origin of all complex commands and decisions

Question 8

The endocrine system

Answer 8

One of the body’s major information systems that instructs glands to release hormones directly into the bloodstream, these hormones are carried towards target organs in the body

Question 9

Gland

Answer 9

An organ in the body that synthesises substances such as hormones

Question 10

Hormones

Answer 10

chemical substances that circulate in the bloodstream and only affect target organs, they are produces in large quantities but disappear quickly

Question 11

The pituitary gland

Answer 11

The main endocrine gland, often called the master gland because it controls the release of hormones from all other endocrine glands in the body

Question 12

Fight or Flight response

Answer 12

1. when a stressor is perceived the hypothalamus triggers activity in the sympathetic branch of the autonomic nervous system
2. The ANS changes from its normal resting state (the parasympathetic state) to the physiologically aroused sympathetic state
3. The stress hormone adrenaline is released into the bloodstream - adrenaline triggers physiological changes in the body e.g. increased heart rate, necessary for the response
4. once the threat has passed the parasympathetic nervous system returns the body to its resting state, it acts as a break and reduces the activities of the body that were increased by the actions of the sympathetic branch, sometimes referred to as the rest and digest response

Question 13

sympathetic state

Answer 13

• increases heart rate
• increases breathing rate
• dilates pupils
• inhibits saliva production
• contracts rectum

Question 14

Parasympathetic state

Answer 14

• decreases heart rate
• decreases breathing rate
• contracts pupils
• stimulates digestion
• stimulates saliva production
• relaxes rectum

Question 15

The structure of a neuron

Answer 15

• Vary in size from less than a millimeter to up to a meter long
• the cell body (or soma), dendrites, axon, myelin sheath, nodes of Ranvier and terminal buttons

Question 16

Cell body (soma) of a neuron

Answer 16

includes a nucleus, which contains the genetic material of the cell

Question 17

Dendrites

Answer 17

branch-like structures that protude from the neuron cell body

Question 18

Axon

Answer 18

carries the impulses away from the cell body

Question 19

Myelin sheath

Answer 19

fatty layer that protects the axon and speeds up chemical transmission

Question 20

Nodes of Ranvier

Answer 20

where the myelin sheath is segmented to maintain the speed of chemical transmission

Question 21

Terminal buttons

Answer 21

Communicate between neurons

Question 22

electric transmission - firing of a neuron

Answer 22

1. when a neuron is in a resting state the inside of the cell is negatively charged compared to the outside
2. 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
   - this creates an electrical impulse that travels down the axon towards the end of the neuron

Question 23

types of neuron

Answer 23

motor neurons, sensory neurons and relay neurons

Question 24

neural networks

Answer 24

Groups of neurons communicating with each other

Question 25

The synapse

Answer 25

includes the space between the neuron (called the synaptic cleft as well as the presynaptic terminal and post synaptic receptor site

Question 26

Synaptic transmission

Answer 26

how signals between neurons are transmitted chemically

Question 27

what happens when the electrical impulse reaches the end of the neuron

Answer 27

the end of the neuron is called the presynaptic terminal, it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles

Question 28

neurotransmitters

Answer 28

chemicals that diffuse across the synapse to the next neuron in the chain, they are taken up by the postsynaptic receptor sites and are then converted back into an electrical impulse
- each has its own specific molecular structure that fits perfectly into a post-synaptic receptor site
- has a specialist function

Question 29

inhibition

Answer 29

decreases the likelihood that the neuron will fire

Question 30

excitation

Answer 30

increases the neurons positive charge and making it more likely to fire

Question 31

Localisation versus holistic theory

Answer 31

• Paul Broca and Karl Wernicke discovered that specific areas of the brain are associated with particular physical and psychological functions
• scientists believed that all parts of the brain were involved in the processing of thoughts and action

Question 32

Localisation of function in the brain

Answer 32

The idea that different parts of the brain perform different tasks and are involved with different parts of the body, if a certain area of the brain becomes damaged the function associated with that area will also be affected

Question 33

hemispheres of the brain

Answer 33

the brain is divided into two symmetrical halves called the left and right hemispheres
activity on the left-hand side of the body is controlled by the right hemisphere and vice versa

Question 34

The cerebral cortex

Answer 34

the outer layer of both hemispheres, about 3mm thick and is what separates us from other animals as it it more developed
- appears grey due to the location of cell bodies

Question 35

the sub-divisions of the cortex of the brain

Answer 35

named after the bones beneath which they lie; the frontal lobe, the pariental lobe, the occipital lobe and the temporal lobe

Question 36

the motor area

Answer 36

located in the back of the frontal lobe, controls voluntary movement in the opposite side of the body and damage results in a loss of control over fine movements

Question 37

the somatosensory area

Answer 37

located in the front of the pariental lobe, a valley separates the frontal lobe and pariental lobe called the central sulcus
it is where sensory information is represented (from the skin)

Question 38

visual area

Answer 38

located in the occipital lobe, works in opposite to the eye

Question 39

auditory area

Answer 39

located in the temporal lobe, analyses speech based information, damage may produce partial hearing loss

Question 40

Broca’s area

Answer 40

responsible for speech production, damage causes Broca’s aphasia which is characterised by speech that is slow, laborious and lacking in fluency

Question 41

Wernicke’s area

Answer 41

responsible for language comprehension, damage leads to Wernicke’s aphasia, impaired language comprehension

Question 42

Brain scan evidence of localisation - Peterson et al

Answer 42

used brain scans to demonstrate how Wernicke’s area was active during a listening task and that Broca’s area was active during a reading task, shows different areas have different functions

Question 43

Brain scan evidence of localisation - Tulving et al

Answer 43

long-term study revealed that semantic and episodic memories reside in different parts of the prefrontal cortex
Now a number of highly sophisticated and objective methods for measuring activity in the brain provide sound scientific evidence

Question 44

Neurosurgical evidence of localisation - Dougherty et al

Answer 44

The practice of surgically removing and destroying areas of the brain to control aspects of behaviour, discovered in 1950s
44 OCD patients undergone angulotomy, after 32 weeks 1/3 met criteria for successful response - shows that symptoms and behaviours are localised

Question 45

Lobotomy

Answer 45

A brutal and imprecise method of neurosurgery, only used in extreme cases of OCD and depression

Question 46

Lashley’s research to disprove localisation

Answer 46

suggests that higher cognitive functions, such as the process of learning are not localised but distributed in a more holistic way in the brain
Karl removed areas of the cortex in rats that were learning a maze, no area was proven to be more important than any other area
The process of learning appeared to require every part of the cortex; learning is too complex to be localised and requires involvement of the whole brain

Question 47

Plasticity and localisation

Answer 47

when the brain has become damaged the appears able to reorganise itself in an attempt to recover the lost function, known as the law of equipotentiality, stroke victims are able to recover those abilities that were seemingly lost as a result of the illness

Question 48

Brain plasticity

Answer 48

The brain has the ability change throughout life;
during infancy, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 at age 2-3 years
More and more research suggests that at any time in life existing neural connections can change or form

Question 49

synaptic pruning

Answer 49

as we age, rarely used connections are deleted and frequently used connections are strengthened

Question 50

what was originally thought about brain plasticity

Answer 50

changes such as synaptic pruning were restricted to the developing brain within childhood and the adult brain would remain fixed and static in terms of function and structure

Question 51

Research into plasticity - Eleanor Maguire et al

Answer 51

studied the brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group - this part of the brain is associated with the development of spatial and navigational skills in humans and other animals
- London cabbies must take a complex test called ‘the knowledge’ which assesses their recall of the city streets, the longer they had been in the job, the more pronounced was the structural differences (positive correlation)

Question 52

Research into plasticity - Dragonski et al

Answer 52

Imaged the brains of medical students before and after final exams, learning-induced changes were seen to have occurred in the posterior hippocampus and the pariental cortex presumably as a result of the exam

Question 53

Functional recovery after trauma

Answer 53

Unaffected areas of the brain are able to adapt and compensate for those areas that are damaged
it is an example of neural plasticity
healthy brain areas may take over
happens quickly after trauma - spontaneous recovery

Question 54

what happens in the brain during recovery?

Answer 54

secondary neural pathways that would not typically be used to carry out certain functions are activated or unmasked to enable functioning to continue
- axonal sprouting
- reformation of blood vessels
- recruitment of homologous areas

Question 55

axonal sprouting

Answer 55

the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways

Question 56

Practical application of plasticity and functional recovery

Answer 56

Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation
Physical therapy may be required to maintain improvements in functioning
Although the brain may have the capacity to fix itself to a point, this process requires further intervention if it is to be completed successfully

Question 57

Negative plasticity

Answer 57

The brains ability to rewire itself can sometimes have maladaptive behavioural consequences, prolonged drug use for example has been shown to result in poorer cognitive functioning as well as an increased risk of dementia later in life
60-80% of amputees have been known to develop phantom limb syndrome- the continued experience of sensations in the missing limb as if it were still there, usually unpleasant- thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss

Question 58

Age and plasticity`

Answer 58

Functional plasticity tends to reduce with age, the brain has greater prosperity for reorganisation in childhood as it is constantly adapting to new experiences and learning

Question 59

Age and plasticity - Ladina Bezzola et al

Answer 59

Demonstrated how 40 hours of golf training produced changes in the neural representation of movement in participants aged 40-60, using fMRI the researchers observed reduced motor cortex activity in the novice golfers compared to a control group - more effective neural representations after training
Neural plasticity does continue throughout lifespan

Question 60

Animal studies - plasticity and functional recovery

Answer 60

David Huber and Turton Wiesel involves sewing one eye of a kitten shut and analysing the brains cortical responses, it was found that the area of the visual cortex associated with he shut eye was not idle (as had been predicted) but continued to process information from the open eye

Question 61

Hemispheric lateralisation

Answer 61

The ability to produce and understand language is controlled by the left hemisphere
language is subject to this
It has been investigated through a series of ingenious experiments conducted by Roger Sperry and his colleagues

Question 62

Roger Sperry

Answer 62

Awarded the novel prize in 1981 due to his split-brain research

Question 63

Split-brain studies

Answer 63

Involved a unique group of individuals, all whom had undergone the same surgical procedures, the separation of the two hemispheres
The communication line between the two hemispheres was removed
This allowed Sperry to seethe extent to which the two hemispheres were specialised for certain functions and whether the hemispheres performed tasks independently of one another

Question 64

Commissurotomy

Answer 64

The corpus callosum and other tissues which connect the two hemispheres are cut down the middle in order to separate the two hemispheres and control frequent epileptic seizures

Question 65

Procedure of split brain research into hemispheric lateralisation

Answer 65

1. An image or word could be projected to the patients visual field and then processed by the opposite side of the brain
   - in the normal brain, the corpus callosum would immediately share the information between both hemispheres
   - presenting the image to one hemisphere of a split brain patient meant that the information could not be conveyed from that hemisphere to the other

Question 66

Key findings of split brain research - describing what you see

Answer 66

`When a picture of an object was shown to a patients right visual field they could easily describe what was seen but not for the left visual field, the patient typically reported that the was nothing there
Lack of language centres in the right hemisphere

Question 67

Key findings of split brain research - recognition by touch

Answer 67

Patients are able to select a matching object from a grab bag of different objects using their left hand, was also able to select an object that was most closely associated with an object presented to the left visual field but could not verbally identify just understood what the object was

Question 68

Key findings of split brain research - composite words

Answer 68

For example, ‘key’ on the left and ‘ring’ on the right, the patient would write with their left hand the word ‘key’ and say the word ‘ring’

Question 69

Key findings of split brain research - matching faces

Answer 69

The right hemisphere appeared dominant, the picture consistently selected when shown to the left visual field, the left hemisphere dominated in terms of verbal description but right in selecting matching pictures

Question 70

split-brain research - demonstrated lateralised brain functions

Answer 70

Sperry’s work has produced an impressive and sizable body of research findings, the left hemisphere is more geared towards analytical and verbal tasks whilst the right is more adept at performing spatial tasks and music, contributes to emotional and holistic content to language
Research suggests that the left hemisphere is the analyser whilst the right is the synthesiser
- a key contribution to our understanding of brain processes

Question 71

split-brain research - strengths of the methodology

Answer 71

• experiments made use of highly specialised and standardised procedures
• typically, participants would be asked to stare at a given point, the ‘fixation point’
• the image projected would be flashed up for 1/10 of a second, meaning the split-brain patient would not have time to move their eyes across the image and so spread the information across both sides of the visual field
• this allowed Sperry to vary aspects of the basic procedure and ensured that only one hemisphere was receiving information at a time
  = a very useful and well-controlled procedure

Question 72

split-brain research - theoretical basis

Answer 72

Sperry’s work prompted a theoretical and philosophical debate about the degree of communication between the two hemispheres in everyday functioning and the nature of consciousness
other researchers argued that the two hemispheres form a highly integrated system and are both involved in everyday tasks

Question 73

split-brain research - theoretical basis, Roland Pucetti

Answer 73

have suggested that the two hemispheres are so functionally different that they represent a form of duality in the brain - we are all two minds but emphasised in split-brain

Question 74

split-brain research - issues with generalisation

Answer 74

many researchers have urged caution in their widespread acceptance, as split-brain patients constitute such an unusual sample of people - there were only 11 who took part in all variations of the basic procedure, all of whom had a history of epileptic seizures, this may have caused unique changes in the brain that have influenced the findings
the control group, made up of 11 people with no history of epilepsy may have been inappropriate

Question 75

functional magnetic resonance imaging (fMRI)

Answer 75

works by detecting the changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain
when a brain area is more active it consumes more oxygen and to meet this increased demand, blood flow is directed to the active are (known as the haemodynamic response)
produces 3D images (activation maps)
showing which parts of the brain are involved in a particular mental process and this has important implications for our understanding of localisation of function

Question 76

Electroencephalogram (EEG)

Answer 76

measures electrical activity within the brain via electrodes that are fixed to an individuals scalp using a skull cap
the scan recording represents the brainwave patterns that are generated from the action of millions of neurons, providing an overall account of brain activity
often used by clinicians as a diagnostic tool as an unusual arrhythmic pattern of activity may indicate neurological abnormalities such as sleep disorders, epilepsy and tumors

Question 77

Event-related potentials (ERPs)

Answer 77

using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to the presentation of a specific task
what remains are event-related potentials: types of brainwave that are triggered by particular events
research as revealed many different forms of ERP and how, e.g., these are linked to cognitive processes such as attention and perception

Question 78

Post-mortem examinations

Answer 78

a technique involving the analysis of a person’s brain following their death
individuals whose brains are subject to this are likely to be those who have deficits in mental processes or behaviour during their lifetime
areas of damage within the brain are examined after death as a means of establishing a likely cause, it may involve comparison with a neurotypical brain

Question 79

strengths of fMRI

Answer 79

• unlike other scanning techniques such as PET, it does not rely on the use of radiation. If used correctly it is virtually risk-free, non-invasive and straightforward to use
• produces images that have very high spatial resolution, depicting detail by the mm and providing a clear picture of how brain activity is localised

Question 80

weaknesses of fMRI

Answer 80

• expensive compared to other neuroimaging techniques and can only capture a clear image if the person stays perfectly still
• it has poor temporal resolution - around 5 seconds time-lag behind the image on screen and the initial firing of neuronal activity
• can only measure blood flow - difficult to tell what kind of brain activity is being represented on screen

Question 81

strengths of EEG

Answer 81

• proved essential in the diagnosis of conditions such as epilepsy, a disorder characterised by random bursts of energy that can only be detected on screen
• contributed to understanding of stages involved in sleep (ultradian rhythms)
• extremely high temporal resolution, can accurately detect brain activity at a resolution of a single millisecond

Question 82

weaknesses of EEG

Answer 82

• generalised nature of the information received
• the EEG signal is not useful for pinpointing the exact source of neural activity, and does not allow researchers to distinguish between activities originating in different but adjacent locations

Question 83

strengths of ERPs

Answer 83

• bring much more specificity to the measurement of neural processes
• excellent temporal resolution - widespread use in the measurement of cognitive functions and deficits
• researchers have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning

Question 84

weaknesses of ERPs

Answer 84

• lack of standardisation in methodology between different research studies - makes it difficult to confirm findings
• in order to establish pure date in ERP studies, background noise and extraneous material must be completely eliminated, and this may not always be easy to achieve

Question 85

strengths of post-mortem examinations

Answer 85

• post-mortem evidence was vital in providing a foundation for early understanding of key processes in the brain
• Paul Broca and Karl Wernicke both relied on PME in establishing links between language, brain and behaviour, decades before neuroimaging even became a possibility

Question 86

weaknesses of post-mortem examinations

Answer 86

• causation, observable damage to the brain may not be linked to the deficits under review but some other unrelated trauma or decay
• ethical issues, consent from the patient before death, patients may not be able to provide informed consent, e.g. HM who lost his ability to form memories and was not able to provide such consent, post-mortem studies have been conducted on his brain still

Question 87

Biological rhythms

Answer 87

That all living organisms are subject to which exert an important influence on the way in which body systems behave
governed by two things:
- the body’s internal biological clocks which are called endogenous pacemakers
- external changes in the environment called exogenous zeitgebers

Question 88

Circadian rhythms

Answer 88

a type of biological rhythm subject to a 24-hour cycle, which regulates a number of body processes such as the sleep/wake cycle and changes in core body temperature

Question 89

the sleep/wake cycle

Answer 89

the fact we feel drowsy at night time and alert during the day demonstrates the effect of daylight, an important exogenous zeitgeber

Question 90

free running

Answer 90

if our biological clock was left to its own devices without the influences of external stimuli such as light

Question 91

Siffre’s cave study

Answer 91

Michael, deprived of exposure to natural light and sound, but with access to adequate food and drink, spent 2 months in the caves of the Southern Alps
- in each case, his ‘free running’ biological rhythm settled down to one that was just beyond the usual 24 hours (around 25 hours) though he did continue to fall asleep and wake up on a regular schedule

Question 92

Jurgen Ashcoff and Rutger Wever study - circadian rhythms

Answer 92

convinced a group of participants to spend 4 weeks in a WWII bunker deprived of natural light, all but one displayed a circadian rhythm between 24 and 24 hours, the natural sleep/wake cycle may be slightly longer than 24 hours but it is entrained by exogenous zeitgebers such as the number of daylight hours and typical meal-times
- should not overestimate the influence of environmental cues on our internal biological clock

Question 93

Simon Folkard et al study - circadian rhythms

Answer 93

studied 12 people who agreed to live in a dark cave for 3 weeks, sleep at 11:45pm and rising at 7:45am looking at a clock, the researchers gradually sped up the clock to be a 22 hour day instead - only one participant was able to adjust to the new regime
- shows we have a strong free running circadian rhythm

Question 94

circadian rhythms - practical application to shift work

Answer 94

knowledge of circadian rhythms has given researchers a better understanding of the adverse consequences that can occur as a result of their disruption (known as desynchronisation)
- night workers experience a period of reduced concentration around 6 in the morning (a circadian trough) meaning mistakes and accidents are more likely
- significant relationship between shift work and poor health, shift workers 3x more likely t develop heart disease which may occur due to the stress of adjusting to different sleep/wake patterns and poor quality sleep during the day
= research into the sleep/wake cycle may have economic implications in terms of how best to manage worker productivity

Question 95

circadian rhythms - practical application to drug treatments

Answer 95

circadian rhythms also coordinate a number of the body’s basic processes such as heart rate, digestion and hormone levels - an effect on pharmacokinetics, the action of drugs in the body and how well they are absorbed and distributed
- there are certain peak times during the day/night that drugs are likely to be at their most effective
- also with the development of guidelines to do with the timing of drug dosing for a whole range of medications including anti-cancer, cardiovascular, respiratory etc.

Question 96

circadian rhythms - use of case studies and small samples

Answer 96

• studies of the sleep/wake cycle tend to involve small groups of participants
• people involved may not be representative of the wider population and limits the extent to which meaningful generalisations can be made
• Siffre observed at the age of 60 his internal clock ticked much more slowly than when he was a young man
  = even when the same person is involved, there are factors that vary which may prevent general conclusions being drawn

Question 97

circadian rhythms - individual differences

Answer 97

individual cycles may vary, therefore generalisations can’t be made
Duffy et al - some people display a natura; preference for going to bed early (known as ‘larks’) whereas some people prefer to do the opposite (‘owls’)
there are also age differences in sleep/wake patterns

Question 98

Infradian rhythms

Answer 98

Takes longer than a day to complete
- the menstrual cycle is an example, it is governed by monthly changes in hormone levels which regulate ovulation - refers to the time between the first day of a woman’s period to the day before her next period
- the typical cycle takes approximately 28 days to complete
- rising levels of hormone oestrogen cause the ovary to develop an egg and release it (ovulation)
- after ovulation the hormone progesterone helps the womb lining to grow thicker
- if pregnancy does not occur, the egg is absorbed into the body, the womb lining comes away and leaves the body (the menstrual flow)

Question 99

Research study - the menstrual cycle, an infradian rhythm

Answer 99

although it is an endogenous system, evidence suggests that it may be influenced by exogenous factors, such as the cycles of other women
- Kathleen Stem and Martha McClinton, menstrual cycles may synchronise as a result of the influence of female pheromones - 29 women with a history of irregular periods, samples of pheromones were gathered from the armpit via cotton pad placed in their armpit, the pads were then treated with alcohol and frozen, to be rubbed on the upper lips of the other women - a different pad for each day of their cycle
- 68% of the women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor’

Question 100

Seasonal affective disorder (SAD)

Answer 100

• a depressive disorder which has a seasonal pattern of onset, classified as a mental disorder using DSM-5
• referred to as the winter blues as symptoms are triggered during winter months, daylight hours are shorter
• a circannual rhythm - subject to a yearly cycle
• can be a circadian rhythm as it may be caused by a disruption of sleep/wake cycle
• the hormone melatonin is implicated in the cause, during the night the pineal gland secretes melatonin until dawn when there’s an increase in light - during the winter months a lack of light means the secretion process continues, its thought to have a knock-on effect on the production of seratonin in the brain which cause the depressive symptoms

Question 101

Ultradian rhythms

Answer 101

occurs during the day
- psychologists identified 5 distinct stages of sleep that all together span approximately 90 minutes - a cycle that continues throughout the course of the night, each of these stages is characterised by a different level of brainwave activity which can be monitored using an EEG

Question 102

stages 1 and 2 of sleep (ultradian rhythms)

Answer 102

the ‘sleep escalator’, are light sleep where the person can be easily woken, brainwave patterns start to become slower and more rhythmic (alpha waves) becoming even slower as sleep becomes deeper (theta waves)

Question 103

stages 3 and 4 of sleep (ultradian rhythms)

Answer 103

involve delta waves which are slower still and have greater amplitude
this is a deep sleep or slow wave sleep and it is difficult to rouse someone

Question 104

Stage 5, REM sleep ( ultradian rhythm)

Answer 104

the body is paralysed yet brain activity speeds up significantly resembling the awake brain
- REM = rapid eye movement, highly correlated with the experience of dreaming

Question 105

evolutionary basis of the menstrual cycle

Answer 105

• menstrual synchrony, is thought by many to have an evolutionary value
• our ancestors thought it may have been advantageous for females to menstruate together and therefore fall pregnant at the same time
• new-borns could be cared for collectively within a social group, increasing the chances of the offspring’s survival
• the validity of the evolutionary perspective has been questioned by some, Jeffrey Schank argued that if there were too many femals cycling together within a social group, this would produce competition for the highest quality males (and thereby lowering the fitness of any potential offspring)
  the avoidance of synchrony would appear to be most adaptive evolutionary strategy and therefore naturally selected

Question 106

methodolgical limitations in synchronisation studies (infradian and ultradian rhythms)

Answer 106

criticisms have been made of early synchronisation studies and the methods employed
- argue that there are many factors that may affect change in a women’s menstrual cycle, including stress, changes in diet, exercise, etc. that may at as confounding variables, any supposed pattern of synchronisation as seen in the studies by McClintock and others is no more than would have been expected to occur by chance
- research typically involves small samples of women and relies on participants self-reporting the onset of their own cycle
- other cycles failed to find any evidence of menstrual synchrony in all-female samples

Question 107

evidence supports the idea of distinct stages in sleep

Answer 107

• a landmark study by William Dement and Nathaniel Ideitman monitored the sleep patterns of 9 adults in a sleep lab
• Brain wave activity was recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol
• REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were
• replications have noted similar findings, though the small size of the original sample has been criticised by some
  REM sleep is an important component of the ultradian sleep cycle

Question 108

Animal studies (infradian rhythms)

Answer 108

• much of the knowledge of the effects of pheromones on behaviour is derived from animal studies, the role of pheromones in animal sexual selection is well-documented
• e.g. sea urchins release pheromones into the surrounding water so other urchins in the colony will eject their sex cells simultaneously
• evidence for the effects in human behaviour remains speculative and inconclusive

Question 109

The superchiasmatic nucleus (SCN)

Answer 109

A tiny bundle of nerve cells located in the hypothalamus of each hemisphere in the brain
One of the primary endogenous pacemakers in mammalian species and is influential in maintaining circadian rhythms
The SCN receives information about light directly from the optic chiasm and this continues even when our eyes are closed, enabling the biological clock to adjust to the changing patterns of daylight whilst we are sleep

Question 110

Optic chiasm

Answer 110

Point at which optic nerve fibers cross in the brain on their way to the visual area of the eye (cerebral cortex)

Question 111

Patricia DeCoursey et al - the SCN

(Chipmunks?)

Answer 111

Destroyed the SCN connections in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80 days
The sleep/wake cycle of the chipmunks had disappeared and by the end of the study a significant proportion of them had been killed by predators

Question 112

Martin Ralph et al - the SCN

( Hamsters?)

Answer 112

Bred ‘mutant’ hamsters with a 20-hour sleep/wake cycle
When SCN cells from the foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters, the cycles of the second group defaulted to 20 hours

Question 113

Animal studies on SCN

Answer 113

They emphasise the role of the SCN in establishing and maintaining the circadian sleep/wake cycle

Question 114

Melatonin

Answer 114

A chemical that induces sleep and is inhibited during periods of wakefulnes

Question 115

The pineal gland and the SCN

Answer 115

The SCN passed the information on day length and light that it receives to the pineal gland, during the night the pineal gland increases production of melatonin

Question 116

Entrainment

Answer 116

The process whereby external factors in the environment can reset our biological clocks

Question 117

Zeitgeber

Answer 117

Time giver

Question 118

What happens to our sleep/wake cycle in the absence of external cues

Answer 118

The free-running biological clock that controls the sleep/wake cycle continues to tick in a distinct cyclical pattern, thus sleeping and wakefulness would seem to be determined by an interaction of internal and external factors

Question 119

Light

Answer 119

A key zeitgeber in humans
It can reset the body’s main endogenous pacemaker, the SCN and thus plays a role in the maintenance of the the sleep/wake cycle
Also has an indirect influence on key processes in the body that control such functions as hormone secretion and blood circulation

Question 120

Scott Campbell and Patricia Murphy

Answer 120

Demonstrated that light may be detected by skin receptor sites even when the same information is not received by the eyes
15 participants were woken at various times and a light pad was shone on the back of their knees
The researchers managed to produce a deviation in the participants sleep/wake cycle of up to 3 hours
This suggests that light is an exogenous zeitgeber that need not necessarily rely on the eyes to influence the brain

Question 121

Social cues

Answer 121

The schedules imposed by parents are likely to be a key influence on babies sleep/wake cycles including adult determined mealtimes and bedtimes
Infants are seldom on the sleep/wake cycle compared to the rest of the family
Their initial sleep/wake cycle is pretty much random and at about 6 weeks of age the circadian rhythms begin
By 16 weeks most babies are entrained

Question 122

Jet lag…

Answer 122

Research suggests that adapting to local times for eating and sleeping (rather than responding to ones own feelings of hunger and fatigue) is an effective way of entraining circadian rhythms and beating this

Question 123

Peripheral oscillators

Answer 123

There are numerous circadian rhythms in many organs and cells of the body, they are found in adrenal gland, oesophagus, lungs, liver, thymus, spleen, pancreas and skin
They can act independently but are highly influenced by the actions of the SCN

Question 124

Francesa Damiola et al

Answer 124

Demonstrated how changing feeding patterns in mice could alter the circadian rhythms of cells in the liver by up to 12 hours whilst leaving the rhythm of the SCN unaffected

Question 125

Beyond the master clock - evaluation

Answer 125

Suggests that there may be other complex influences on the sleep wake cycle aside from the master clock (the SCN)

Question 126

Ethics in animal studies - the SCN

Answer 126

Issue of generalising from animal studies to humans
In DeCoursey et al study the animals were exposed to considerable harm, and subsequent risk when they were returned to their natural habitat
Whether what we learn from investigations justifies the averse procedures is a matter of debate

Question 127

Influence of exogenous zeitgeber may be overstated

Answer 127

Laughton Miles at al - blind man from birth with a circadian rhythm of 24.9 hours, despite exposure to social cues his sleep/wake cycle could not be adjusted - took sedatives at night and stimulants in the morning to keep pace with 24-hour world
Studies of individuals in attic regions show normal sleep patterns despite the prolonged exposure to light

Question 128

Methodological issues in studies - the SCN

Answer 128

Campbell and Murphy study yet to be replicated
Psychologists have been critical of the manner in which the study was conducted and have suggested that there may have been some limited light exposure to the participants eyes - a major confounding variable
Also isolating an exogenous zeitgeber (light) in this way does not give us an insight into the many other zeitgeber that influence the sleep/wake cycle and the extent to which these may interact