Biopsychology Flashcards

Question

What are motor neurons?

Answer 1

These connect the central nervous system to effectors such as muscles and glands . They have short dendrites and long axons.

Answer 2

These connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons.

Answer 3

The brain and spinal cord.

Answer 4

Contains pons, medulla and cerebellum. Pons and medulla Is a continuation of the spinal cord carrying on into the bottom of the brain, the brain stem, mainly composed of sensory and motor neurons. The cerebellum controls movement and motor coordination.

Answer 5

The diencephalon. The cerebral hemispheres.

Answer 6

Thalamus Hypothalamus

Answer 7

Concerned with relaying sensory information from the brainstem to the cortex.

Answer 8

Controls basic functions such as hunger, thirst, sexual behaviour, also controls the the pituitary gland.

Answer 9

Controls higher level cognitive and emotional processes

Answer 10

The limbic system The basal ganglia The cerebral cortex

Answer 11

involved in learning memory and emotions

Answer 12

Involved in motor activités and movement.

Answer 13

Is involved with planning, problem-solving, language, consciousness and personality.

Answer 14

Sends information to the central nervous system from the outside world, and transmits messages from the CNS to muscles and glands in the body.

Answer 15

somatic nervous system autonomic nervous system.

Answer 16

Automatic behaviour by the body which controls bodily arousal, body temperature, homeostasis, heart rate and blood pressure.

Answer 17

The sympathetic nervous system. Parasympathetic nervous system.

Answer 18

Leads to increased arousal e.g. increase in heart rate and blood pressure. Fight and flight response

Answer 19

Leads to decreased arousal e.g. decreased heart rate and blood pressure. Returns body to normal after flight and fight response

Answer 20

hormones are chemical messengers secreted from glands in the body which pass through the bloodstream to cause changes in our body or behaviour.

Answer 21

The endocrine system is a network of glands across the body that secrete chemical messages called hormones.

Answer 22

``` Thyroid Adrenal Medulla Adrenal cortex Testes Ovaries Pineal ```

Answer 23

Regulates metabolic rate and protein synthesis

Answer 24

Adrenaline and noradrenaline

Answer 25

Used in flight of fight response: | Increased heart rate, blood pressure, release of glucose and fats for energy.

Answer 26

Corticosteroids

Answer 27

Release of glucose and fats for energy; suppression of the immune system.

Answer 28

Testosterone

Answer 29

Male sexual characteristics, muscle mass.

Answer 30

Female sexual characteristics, menstruation, pregnancy.

Answer 31

Effects the sleep-wake cycle.

Answer 32

It is the master gland and controls release of hormones many from the endocrine system. It is divided into the anterior and posterior.

Answer 33

ACTH Prolactin Growth hormone

Answer 34

Stimulates release of corticosteroids during flight-fight response.

Answer 35

Stimulates production of milk from mammary glands. (breasts)

Answer 36

Cell growth and multiplication.

Answer 37

Vasopressin Oxytocin

Answer 38

Regulating water balance

Answer 39

Uterine contractions during childbirth.

Answer 40

Stress is experiences when a person's perceived environmental, social and or physical demands exceed their perceived ability to cope.

Answer 41

The fight or flight response.

Answer 42

The fight or flight response is hard-wired response into our brains are represents an evolutionary adaptation designed to increase an organism's chances of survival in life threatening situations.

Answer 43

The sympathomedullary pathway The pituitary-adrenal system.

Answer 44

Deals with acute (short term, immediate) stressors such as personal attack.

Answer 45

Deals with chronic (long-term, ongoing) stressors such as a stressful job.

Answer 46

Stressor is recognised by the Hypothalamus

Answer 47

Hypothalamus sends a message to the sympathetic branch of the autonomic nervous system- which causes a state of high physiological arousal.

Answer 48

Neurons send signals to adrenal medulla, which causes the release of adrenaline and noradrenaline into bloodstream.

Answer 49

The release of adrenaline and noradrenaline into bloodstream helps prepare the body for action to survive life threatening stressors resulting in the fight or flight response. By increasing: Heart rate, breathing rate and blood pressure Oxygen supply to brain and muscles Salivation reduced, pupil dilation, sweating to cool body, digestion slows Blood flow diverted from skin surface to heart and brain.

Answer 50

Once the stressor has passed or been coped with the parasympathetic branch of the autonomic nervous system is activated which returns the body to a resting state: e.g. heart rate and blood pressure return to normal.

Answer 51

The sympathomedullary pathway.

Answer 52

The hypothalamic pituitary adrenal system.

Answer 53

Stressor is recognised by the hypothalamus

Answer 54

Hypothalamus sends a message to the pituitary gland which releases ACTH into the bloodstream.

Answer 55

ACTH travels to the adrenal cortex which releases corticosteroids into the bloodstream.

Answer 56

Corticosteroids leads to positive effects, liver releases energy in form of glucose, lowered sensitivity to pain.

Answer 57

Negative effects as a response to the body's response to chronic long term stressors such as higher blood pressure, lower immune system response (immunosuppression) and impaired cognitive performance.

Answer 58

The link between brain structures and their functions e.g. language memory etc.

Answer 59

2, left and right.

Answer 60

The motor cortex controls voluntary movements. Both hemispheres of the brain have a motor cortex with each side controlling muscles on the opposite side of the body. Different areas of the motor cortex controls different parts of the body and these are in the same sequence as in the body. (e.g. the part of the cortex controlling the foot is next to the part controlling the leg). Located in frontal lobe.

Answer 61

The sensorimotor cortex registers sensory information from different areas of the body e.g. pain, temperature , pressure. Both hemispheres have a sensorimotor cortex with each side receiving information from the opposite side of the body. Located in parietal lobe.

Answer 62

Is the idea that certain functions have certain locations or areas within the brain.

Answer 63

Processes visual information starts when light enters the eye and strikes photoreceptors on the retina at the back of the eye. Nerve impulses then travel up the optic nerve to the thalamus and are then passed on to the visual cortex in the hindbrain. The right hemisphere's visual cortex processes visual information received by the left eye and vice-versa. The visual cortex contains different regions to do with colour, shape, movement etc.

Answer 64

Processes auditory information (sound) begins in the inner ear's cochlea where sound waves are converted into nerve impulses which travel along the auditory nerve to the brain stem. then to the auditory cortex which recognises the sound and may form an appropriate response to that sound.

Answer 65

Contains two areas Broca's area and Wernicke's areas. Broca's and Wernicke's areas are connected by a loop which ties together language production and comprehension.

Answer 66

Broca's Area is generally considered to be the main centre of speech production. The neuroscientist after whom this brain area is named found that patients with speech production problems had lesions to this area in their left hemisphere but lesions in the right hemisphere did not cause this problem. More recent research indicates Broca's area is also involved with performing complex cognitive tasks e.g. solving maths problems.

Answer 67

Wernicke's area is also in the left hemisphere and is concerned with speech comprehension. The neuroscientist after whom this brain area is named found that lesions in this brain area could produce but not understand/comprehend language. Wernicke's area is divided into the motor region (which controls movements of the mouth, tongue and vocal cords) and the sensory area (where sounds are recognised as language with meaning).

Answer 68

At the back of the frontal lobe in both hemispheres.

Answer 69

At the front of both parietal lobes.

Answer 70

in the occipital lobe at the back of the brain.

Answer 71

Is located in the temporal lobe.

Answer 72

Research support from case studies – Phineas Gage was in an accident which caused him to lose part of his frontal love which altered his personality – The frontal lobe may play a role in mood regulation this supports the existence of localisation theory. Petersen et al 1988 used brain scans to demonstrate how Wernicke's area was active during a listening task and Broca's area was active during a reading task, suggesting that these areas of the brain have different functions.

Answer 73

Equipotentiality theory argues that although basic brain functions such as the motor cortex and sensory functions are controlled by localised brain areas, higher cognitive functions such as problem solving are not localised. Research has found that damage to brains can result in other areas of the brain taking over control of functions that were previously controlled by the part of the brain that has been damaged. Therefore, the severity of brain damage is determined by the amount of damage to the brain rather than the particular area which has been damaged. Karl Lashley ('50) suggests that higher cognitive functions, such as the processes involved in learning, are not localised but distributed in a more holistic way in the brain. Lashley removed areas of the cortex between 10-50% in rats that were learning a maze. No area was proven to be more important than any other area in terms of the rats' ability to learn the maze. The process of learning appeared to require every part of the cortex, rather than being confined to a particular area. This seems to suggest that learning is too complex to be localised and requires the involvement of the whole of the brain.

Answer 74

The idea that the two hemispheres of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other, as in the example of language.

Answer 75

A bundle of nerve fibres called the corpus callosum..

Answer 76

A bundle of nerve fibres which allows information to be received by one hemisphere to be transferred to hate there hemisphere.

Answer 77

Sperry ('68)

Answer 78

Participants sat in front of aboard with a horizontal rows of light and were asked to stare at the middle point. The lights then flashed across their right and left visual field. Participants reported lights had only flashed up on the right side of the board. When their right eye was covered and the lights were flashed to the left side of their visual field they claimed not have seen any lights at all. However, when asked to point at which lights had lit up they could do.

Answer 79

Shows that participants had seen the lights in both hemispheres but that material presented to the left eye could not be spoken about as the right hemisphere (which receives information from the left eye) has no language centre and thus cannot speak about the visual information it has received. It can communicate about this in different non-visual ways, however e.g. participants could point at what they had seen.

Answer 80

This proves that in order to say that one has seen something the region of the brain associated with speech must be able to communicate with areas of the brain that process visual information.

Answer 81

Because split-brain patients are so rare, findings as described above were often based on samples of 2 or 3, and these patients often had other neurological problems which might have acted as a confounding variable. Also, patients do not always have a complete splitting of the 2 hemispheres. These factors mean findings should be generalised with care. More recent research has contradicted Sperry's original claim that the right hemisphere could not process even basic language. For example, the case study of Patient JW found that after a split-brain procedure he developed the ability to speak out of his right hemisphere which means that he can speak about information presented to either his left or his right visual field, contradicting findings from Sperry's research.

Answer 82

Strong methodology, the experiments involving split-brain patients made use of highly specialised and standardised procedures. Sperry's method of presenting visual information to one hemispheric field at a time was quite ingenious. Typically, participants would be asked to stare at a given point, the 'fixation point', whilst one eye was blindfolded. The image projected would be flashed up for one-tenth of a second, meaning the split-brain patient would not have time to move their eye across the image and so spread the information across both sides of the visual field, and subsequently, both sides of the brain. This allowed Sperry to vary aspects of the basic procedure and ensured that only one hemisphere was receiving information at a time. Thus he developed a very useful and well-controlled procedure.

Answer 83

Plasticity refers to neurological changes as a result of learning and experience. Although this traditionally associated with changes in childhood, recent research indicates that mature brains continue to show plasticity as a result of learning.

Answer 84

Functional recovery refers to brain functions moving from a damaged to an undamaged location after traumatic brain injury.

Answer 85

Learning new skills A result of development changes Response to direct trauma to area of the brain. Response to indirect effects of damage such as brain swelling or bleeding.

Answer 86

Kuhn 2014 found that playing video games for 30+ minutes a day resulted in increase brain matter int he cortex, hippocampus and cerebellum. Thus, the complex cognitive demands involved in mastering a video game caused the formation of new synaptic connects in brain sites controlling spatial navigation, planning, decision making etc. Kempermann 1998 found that rats housed in more complex environments showed an increase in neurons compared to a control group living in simple cages, changes were particularly clear in the hippocampus, associated with memory and spatial navigation.

Answer 87

Victims who have experienced brain damage and thus lost some brain functions have shown that the brain has an ability to re-wire itself with undamaged sites taking over the functions of damages brain sites. Thus, neurons next to damaged brain sites can take over at least some of the functions that have been lost.

Answer 88

Neuronal unmasking Stem cells.

Answer 89

Wall 1977 noticed the brain contained 'dormant synapses' - neural connections which have no function. However, when brain damage occurs these synapses can become activated and open up connections to regions of the brain that are not normally active and take over the neural function that has been lost as a result of damage.

Answer 90

Stem cells are unspecialised cells which can become specialised to carry out different types of task: for example, taking on behaviour of neurons in the brain. Current research is examining ways in which stem cells might be used to aid recovery from brain trauma, for example they could be implanted to replace dead cells or to release substances which encourage growth or recovery of damaged cells.

Answer 91

Age, there is a negative correlation between functional recovery and age, i.e. young people have a higher ability to recover which declines as we age.

Answer 92

Level of education is positive correlated with speed of recovery from traumatic brain injuries. Schneider found that patients with college education were x7 times more likely to than those who did not finish college to recover from their disability after 1 year.

Answer 93

Functional magnetic resonance imaging (fMRI) Electroencephalogram Event-related potentials Post-mortem examinations

Answer 94

A brain scanner which measures increased blood low to brain sites when individuals are asked to perform cognitive/physical tasks. Increased blood flow indicates increase demand for oxygen in that area. Thus, fMRI can help build up a map of brain localisation. For example, an fMRI scan could identify brain sites which received increased oxygen when a participant is asked to move maths problems.

Answer 95

fMRI is a non-invasive technique and does not expose the brain to potentially harmful radiation.

Answer 96

fMRI only measures blood flow- it does not directly measure neural activity and is not, therefore, a totally objective measure of neural activity in the brain. fMRI may overlook the interconnectivity of the brain sites. By only focusing on brain sites receiving increased blood flow, it fails to account for the importance of brain sites connecting/communicating with each other.

Answer 97

An electroencephalogram measures electrical activity in the brain using electrodes attached to the scalp, and measures how electrical activity in the brain varies over time/ in different stages e.g. waking vs asleep. Electroencephalogram readings can detect epilepsy and Alzheimer's.

Answer 98

Electroencephalogram have medical applications in diagnosing disorders such as epilepsy and Alzheimer's. Records brain activity over time and can, therefore, monitor changes as a person switches from task to task or one state to another (e.g. falling asleep).

Answer 99

Electroencephalogram only monitor electrical activity in outer layers of the brain, therefore, cannot reveal electrical activity in deeper brain sites. Not highly accurate- therefore cannot distinguish differences in activity between 2 closely adjacent areas.

Answer 100

Measures small voltages of electrical activity when a stimulus is presented. Because these small voltages are difficult to pick out from other electrical signals in the brain, the stimulus needs to be repeatedly presented, and only signals which occur every time the stimulus is presented will be considered an event-related potential for that stimulus.

Answer 101

Sensory ERPS Cognitive ERPS

Answer 102

A sensory event-related potential are those that occur within 100milliseconds of stimulus presentation.

Answer 103

Those that occur 100milliseconds or more after stimulus presentation.

Answer 104

The brain's 1st recognition of a stimulus.

Answer 105

Information processing and evaluation of the stimulus.

Answer 106

Event-related potentials provide a continue measure of neural activity in response to a stimulus. Therefore, changes to the stimulus can be directly recorded. They have excellent temporal resolution. They are much more specific to the measurement of neural processes than could ever be achieved using raw Electroencephalogram data.

Answer 107

ERPS only monitor electrical activity in outer layers of the brain, therefore, cannot reveal electrical activity in deeper brain sites. A further issue its hat, in order toe establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, and this may not always be easy to achieve.

Answer 108

A technique involving the analysis of a person's brain following their death. In psychological research, individuals whose brains are subject to a post-mortem are likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime.

Answer 109

Allow for detailed examinations and measurement of deep brain structures e.g. the hypothalamus which is not measurable by brain scans.

Answer 110

Various factors can act as confounding variables and might confuse findings/conclusions. For example, length of time between death and post-mortem, other damage caused to the brain either during death or as a result of disease, age at death, drugs given in months prior to death etc. A further problem is that post-mortem studies raise ethical issues of consent from the patient before death. Patients may not be able to provide informed consent. For example in the case of HM who lost his ability to form memories and was not able to provide such consent - nevertheless post-mortem research has been donated on his brain.

Answer 111

Circadian rhythms Ultradian rhythms Infradian rhythms

Answer 112

A type of rhythm that follows a 24-hour cycle e.g. the sleep wake cycle.

Answer 113

A type of rhythm that occurs more than once a day e.g. the cycles of REM and NREM sleep in a single night's sleep.

Answer 114

Are rhythms that occur less than one a day e.g. menstruation (monthly) or hibernation

Answer 115

Distinct patterns of changes in body activity that conform to cyclical time periods.

Answer 116

Endogenous pacemakers. Exogenous zeitgebers

Answer 117

Internal biological structures that control and regulate the rhythm.

Answer 118

External environmental factors that influence the rhythm.

Answer 119

Sleep-wake cycle once everyday Body temperature (max in the afternoon 38 C and minimum in the early morning 36 C, may also slightly drop between 2pm and 4pm which is why we feel sleepy in the afternoon.

Answer 120

Optimise and organism's physiology and behaviour to best meet the varying demands of the day/night cycle.

Answer 121

The cycle is controlled by a 'biological clock' (endogenous pacemaker) but is also influenced by external cues (exogenous zeitgebers) such as light.

Answer 122

When we feel drowsy at night and feel alert during the day, this cycle lasts 24-25hours and is repeated daily. This shows the effect of daylight, an important exogenous zeitgeber on the sleep/wake cycle.

Answer 123

The endogenous pacemakers controlling the sleep-waking cycle is located in the hypothalamus. Patterns of light and darkness are registered by the retina, travel up the optic nerves to where these nerves join the optic chiasma, then pass into the suprachiasmatic nucleus of the hypothalamus. If this nerve connection is severed circadian rhythms become random. The same effect is produced by damaging the SCN of rats, and people born without eyes cannot regulate bodily rhythms.

Answer 124

Ralph's study Yakazaki study on isolated lungs and livers

Answer 125

Ralph bred a group of hamsters to follow a shortened 20hour circadian cycle. Suprachiasmatic nucleus cells were removed and transplanted into the brains of rat foetuses with normal rhythms. Once born, these rats adopted a 20hour cycle. Their brains were then transplanted with Suprachiasmatic nucleus cells from 24-hour cycle hamsters and within a week their cycles had adopted this new 24 cycle. When cells from the Suprachiasmatic nucleus were removed from rats the 24-hour cycle of neural activity persisted in the isolated cells.

Answer 126

Yakazaki found that isolated lungs and livers, and other tissues grown in a lab still persist in showing circadian rhythms. This suggests cells are capable of maintaining a circadian rhythm even when they are not under the control of any brain structures and that most bodily cells are tuned in to following a daily circadian rhythm.

Answer 127

All of this evidence points to the fact that circadian rhythms are primarily controlled by evolutionarily-determined, biological structures that exert a strong influence on us to maintain normal sleep-waking patterns.

Answer 128

Siffre 1975 Innult Indians in the Artic Circle

Answer 129

In 1975 Siffre spent 6 months underground in an environment completely cut off from all exogenous zeitgebers. Although he organised his time in regular patterns of sleeping and waking his body seemed to have a preference for a 25 hour rather than a 24-hour cycle. This implies that Circadian rhythms are mainly controlled by endogenous peacekeepers rather than exogenous zeitgebers.

Answer 130

Inuit Indians who live in the Artic Circle inhabit an environment that has hardly any darkness in summer and hardly any light in winter. if the sleep-waking cycle was primarily controlled by exogenous zeitgebers they would tend to sleep a huge amount in winter and hardly at all in summer. However, this is not the case - they maintain a fairly regular pattern of sleeping and waking all year around.

Answer 131

Heart rate, metabolic rate, breathing rate and body temperature all reach maximum values in the late afternoon/early evening and minimum values in the early hours of the morning. If we reverse our sleep-waking pattern these rhythms persist. This indicates human bodies are evolved for activity in the day and rest at night and, indeed, being nocturnal or disrupting the circadian cycle is highly stressful and physiologically and psychologically harmful.

Answer 132

In the hypothalamus

Answer 133

Patterns of light and darkness are registered by the retina, which travels up the optic nerves to where these nerves join the optic chiasma and then pass into the suprachiasmatic nucleus of the hypothalamus. Where the endogenous pacemaker is located which will control and regulate the rhythm.

Answer 134

If the nerve connection that links the optic nerves to the optic chimes and then pass into the suprachiasmatic nucleus of the hypothalamus is severed circadian rhythms become random. The same effect is produced by damaging the suprachiasmatic nucleus of rats. People born without eyes cannot also regulate bodily rhythms.

Answer 135

Rhythms that last longer than 24hours and can be weekly, monthly or annually.

Answer 136

Female menstrual cycle Seasonal affective disorder Hibernation

Answer 137

Female menstrual cycle is regulated by hormones, that promote ovulation or stimulate the uterus for fertilisation. Ovulation occurs roughly halfway through cycle, when oestrogen levels are highest; usually lasts for 16-32 hours. After ovulation, progesterone levels increase, ready for possible embryo implantation. A typical menstrual cycle is approx, 28 days; however, there is considerable variation, 23 days to 36 days.

Answer 138

While it is logical to assume that infradian rhythms, in particular the menstrual cycle, are governed by internal factors (endogenous pacemakers) such as hormonal changes, research suggests that these infradian rhythms are heavily influenced by exogenous zeitgebers.

Answer 139

Infradian rhythm related to the seasons (yearly cycle), that says people are more depressed in winter months due to increased production of Melatonin. Melatonin is secreted by the pineal gland at night, longer nights means more increased melatonin secretion which is linked to increase in depressive symptoms.

Answer 140

Reinberg 1967 examined a women who spent three months in a cave with only a small lamp to provide light. Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days. This result suggests that the lack of light an exogenous zeitgeber in the cave affected her menstrual cycle, and therefore demonstrates the effect of external factors on infradian rhythms. Russell et al 1980 found that female menstrual cycle became synchronised with other females through odour exposure. In one study, sweat samples from one group of women were rubbed onto the upper lip of another group. Despite the fact that the two groups were separate, their menstrual cycles synchronised. This suggests that the synchronisation of menstrual cycles can be affected by pheromones (exogenous zeitgeber), which have an effect on people nearby rather than on the person producing them.

Answer 141

A rhythm that lasts fewer than 24hours.

Answer 142

Human sleep patterns Meal patterns

Answer 143

Rapid eye movement and Non rapid eye movement

Answer 144

Every 90mins during sleep. | Up to 5 full cycles per night

Answer 145

Stage 1 and 2 are 'tight sleep' stages: brain patterns become slower (starting with alpha waves, processing to theta waves). Stages 3 and 4 are 'deep sleep' or slow wave sleep stage ( associated with delta waves) Stage 5 is rapid eve movement or dream sleep. Body is paralysed; desynchronised brain waves.

Answer 146

Randy Gardener remained awake for 264 hours, after this experience, Randy slept for just 15 hours and over several nights he recovered only 25% of his lost sleep. Interestingly, he recovered 70% of Stage 4 sleep, 50% of his REM sleep and very little of the other stages. These results highlight the degree of flexibility in terms of the different stages within the sleep cycle and the variable nature of this ultradian rhythm. Tucker et al 2007 found significant differences between participants in terms of the duration of each stage, particularly stages 3 and 4 just before REM sleep. This demonstrates that there may be innate individual differences in ultradian rhythms, which means it is worth focusing on these differences during investigations into sleep cycles. Low ecological validity in some of these studies, the way in the research conducted such as sleep patterns participants are often to high levels of control and hooked up to monitors that measure their sleep patterns which can be invasive, which can lead them to sleep in a way that differs from their usual sleep cycle and as a result lacking ecological validity which could lead to false conclusions being drawn.

Answer 147

Sleep-waking cycle.

Answer 148

The suprachiasmatic nucleus is one of the primary endogenous pacemakers in mammalian species and is influential in maintaining circadian rhythms such as the sleep/wake cycle. Nerve fibres connected to the eye cross an area called the optic chiasm on their way to the visual area of the cerebral cortex. The suprachiasmatic nucleuses just above the optic chiasm. It recieves information about light directly from this structure. This continues even when our eyes are closed, enabling the biological clock to adjust to changing patterns of daylight whilst we are asleep.

Answer 149

Patricia DeCoursey et al 2000 Martin Ralph et al 1990

Answer 150

Patricia DeCoursey et al 2000 destroyed the SCN connections in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80days. The sleep/wake cycle of the chipmunks disappeared and by the end of the study a significant proportion of them had been killed by predators presumably because they were awake and vulnerable to attack when they should have been asleep.

Answer 151

Martin Ralph et al 1990 bred 'mutant' hamsters with a 20-hour sleep wake cycle. When suprachiasmatic nucleus cells from the foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters, the cycles of the second group defaulted to 20hours.

Answer 152

Both of these studies emphasise the role of the suprachiasmatic nucleus in establishing and maintaining the circadian sleep/wake cycle.

Answer 153

The SCN passes information on day length and light that it receives to the pineal gland. During the night, the pineal gland increases production of melatonin a chemical that induces sleep and is inhibited during periods of wakefulness. Melatonin has also been suggested as a casual factor in seasonal affective disorder.

Answer 154

Light Social cues.

Answer 155

Light is a key zeitgeber in humans. It can reset the body's main endogenous pacemaker the suprachiasmatic nucleus, and thus plays a role in the maintenance of the sleep/wake cycle.

Answer 156

Campbell and Murphy 1998

Answer 157

Light may be detected by skin receptors sites on the body when the same information is not received by the eyes. 15 participants, whom were woken at various times using light shone on the back of their knees. Which produces a deviation in their normal sleep/wake cycle of up to 3 hours in some cases. Suggest light is important factor affecting the sleep/wake cycle which doesn't only have to be on our eyes it can be anywhere on the body.

Answer 158

Babies initial sleep/wake cycle is very random. Circadian rhythms start around 16 weeks. Thus schedules imposed by parents are a key influence e.g. meal times and bedtimes in forming sleep/wake cycles. Research also shows adapting to local time for eating and sleeping is an effective way of beating jet lag.

Answer 159

Generalisation issues Ethical issues e.g. DeCoursey study- considerable harm and subsequent risk.

Answer 160

Siffre cave study evidence against the importance of exogenous zeitgebers, shows that light may not have an important effect on the sleep wake cycle.

Answer 161

There is a practical application, that is using light exposure to avoid jet lag. Jet lag can be a severe condition causing sleep, appetite and mood disturbance. By understanding the role of exogenous zeitgebers have on our sleep we can decrease the impacts jet lag has on our sleep wake cycles.