Biopsychology Flashcards
1
Q
What are the two components of the nervous system?
A
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
2
Q
What is the human nervous system?
A
Complex network of nerve cells that carry messages to and from the brain and spinal cord to other parts of the body to communicate with each other.
3
Q
What is the CNS split into?
A
Brain
Spinal cord
4
Q
What is the PNS split into?
A
Somatic nervous system
Autonomic nervous system
5
Q
What is the autonomic system then split into?
A
Sympathetic NS
Parasympathetic NS
6
Q
What is the nervous system and what does it help do?
A
network of nerve cells carrying messages to and from the brain and spinal cord to different parts of the body.
7
Q
What does the CNS do?
A
Receives information from the senses and controls the body’s responses
8
Q
What is the Peripheral nervous system?
A
Part of the nervous system that is outside of the brain and spinal cord
9
Q
What is the brain responsible for?
A
Coordinating sensation, intellectual and nervous activity
10
Q
What is the spinal cord?
A
Bundle of enclosed nerve fibers which connect nearly all parts of the body with the brain through spinal nerves.
11
Q
What is the voluntary and conscious control system?
A
Somatic nervous system
12
Q
What does the somatic nervous system contain?
A
Contains sensory + motor nerves that control skeletal muscles like joints. Typically receive and act on external stimuli.
13
Q
What is the autonomic nervous system and what does it contain?
A
Unconscious thought.
Contains nerves that control heartbeat.
Adjusts and maintains body’s internal environment
14
Q
What is the parasympathetic nervous system responsible for?
A
Calms the body after an emergency state.
15
Q
What is the parasympathetic nervous system involved in?
A
energy conservation and digestion
16
Q
What is the sympathetic nervous system involved in?
A
Responses that help us deal with fight or flight
17
Q
Where is the relay neuron found?
A
In the CNS
18
Q
What does the relay neuron allow
A
Communication between motor and sensory neurons
19
Q
What are sensory neurons? and what do they do?
A
They carry sensory receptors to spinal cord / brain. Sensory neurons convert info from receptors into nerve impulses. When impulses reach brain they are translated into sensations (eg: heat) so organism can react appropriately
20
Q
What are motor neurons? and what do they do?
A
Form synapses with muscles and control their contractions. Motor carries relay neuron to allow the muscle to then contract.
21
Q
What are the two types of neurotransmitters?
A
Excitatory and inhibitory
22
Q
What is an exitatory neurotransmitter? and give an example.
A
Nor-adrenaline.
Excitatory neurotransmitters are the system’s ‘on switches’ which increase the likelihood of an excitatory signal being sent to the post synaptic cell which is then more likely to fire.
23
Q
What is an inhibitory neurotransmitter? and give an example.
A
Serotonin.
Nervous system’s ‘off switches’ which decrease the likelihood of neurons firing. Generally responsible for calming mind, body and inducing sleep.
24
Q
What is the name of a junction between two neurons?
A
A synapse.
25
What happens when an impulse reaches the end of a neuron? Describe synaptic transmission.
Causes a neurotransmitter to be released into synaptic cleft. Neurotransmitter then diffuses across post synaptic membrane before binding to receptor cells, relaying the message.
26
What is the pituitary gland controlled by?
Hypothalamus.
27
What do the endocrine glands do?
They produce and secrete hormones. They are chemical substances that regulate activity of cells or organs in the body.
28
What are the 5 glands?
```
Pituitary
Adrenal
Hypothalamus
Ovaries
Testies
```
29
What does the endocrine system do?
Regulated by feedback similar to how a thermostat regulates temperature in a room. Signal sent from hypothalamus to pituitary gland in form of a 'releasing hormone' causing the pituitary gland to secrete a 'stimulating hormone' into the bloodstream. Hormone signals target gland and as levels of the hormone increase, hypothalamus shuts down secretion of stimulating hormone.
30
What are hormones?
Chemicals circulating in bloodstream and they are carried to target sites throughout the body. The come into contact with most cells but only affect those known as target cells - are able to respond as they have receptors for that hormone.
31
What is the pituitary gland?
Master gland. As hormones are released by P.G the hormones control and stimulate the release of hormones from other glands in the endocrine system.
32
What is the pituitary gland divided into?
Anterior (front) + posterior (rear)
33
What does the anterior pituitary gland do?
Releases ACTH as a response to stress - ACTH stimulates adrenal glands to produce CORTISOL.
Also produces LH and FSH - sexual characteristics.
34
What does the posterior pituitary gland do?
Releases OXYTOCIN, which stimulates contraction of uterus during childbirth. Also important for mother-infant bonding.
35
Describe the adrenal glands and where are they located?
2 of them sit on top of kidneys.
Outer part of each gland = adrenal cortex
Inner region of each gland = adrenal medulla.
Difference is that hormones released by adrenal cortex are necessary for life whereas adrenal medulla hormones are not.
36
What hormones are produced by the adrenal glands?
Adrenal cortex produces CORTISOL.
If cortisol level is low, individual has a low B.P, poor immune system and an inability to deal with stress. Tf adrenal cortex produces aldosterone responsible for maintaining blood volume + B.P.
Adrenal medulla releases adrenaline and noradrenaline, hormones preparing body for fight or flight.
37
What does nor adrenaline do?
Constricts blood vessels, causing blood pressure to increase.
38
What does the amygdala do in fight-or-flight responses?
The part of the brain that is triggered in fight-or-flight responses. Associates sensory signals with emotions associated with fight-or-flight such as fear.
39
How does the amygdala communicate with the hypothalamus in the fight-or-flight response?
Sends a distress signal to hypothalamus which then communicates to the rest of the body via the sympathetic NS for a response.
40
What are the two major stress reponses? and their meanings..
Acute (sudden) stressors such as a personal attack.
Chronic (ongoing) stressors such as a stressful job.
41
What does the SNS then do after hypothalamus has called it because of the amygala? and then what does the adrenaline do?
Adrenaline Sends signal to adrenal medulla to release adrenaline into blood.
Circulates body, affecting target cells, heart beats faster to push blood to the muscles and heart. Blood pressure and breathing rate increases. Release of glucose + fats to provide supply for energy
42
What does the PNS do after the fight-or-flight response?
Once the threat has gone, autonomic nervous system dampens down stress responses causing a decrease in heart rate and blood pressure and digestion begins again.
43
How does the brain respond to chronic stressors?
If brain continues to perceive something threatening the second system kicks in. Hypothalamus activates the HPA axis.
44
What does the abbreviation HPA stand for?
Hypothalamus
Pituitary gland
Adrenal glands.
45
What does the H P A axis do?
Hypothalamus - stimulates (CRH) into the blood.
Pituitary gland - CRH causes pituitary to produce + release ACTH targetting cells in adrenal glands
Adrenal gland - ACTH stimulates adrenal cortex to release various stress hormones including cortisol causing a positive effect - a burst of energy.
46
What is the 'tend and befriend' evaluation point in fight or flight response
Taylor et al (2000) suggests for females, responses to stress are due to tend and befriend than fight or flight.
Involves protecting themselves/young ones through nurturing behaviours (tending) and forming protective alliances (befriending).
They may have a different strategy to coping with stress because of the context of being the caregiver of the child.
47
What are the negative consequences of the fight or flight response - eval point.
Stress of modern life rarely require such levels of physical activity - problem arises when response is repeatedly activated eg: increased B.P, a characteristic of SNS activation can lead to physical damage.
48
Fight or flight does not tell the whole story - eval point.
Gray (1988) aruges first phase of reaction to a threat is not to fight or flee but to avoid confrontation - animals often display 'freeze responses' - not included.
49
What is localisation of function?
Localisation of function means that specific functions (language, memory, hearing, etc) have specific locations within the brain.
50
What is the motor cortex's primary function?
Responsible for generation of voluntary motor movement.
51
Where is the motor cortex located in the brain? (what does each bit control?)
Frontal lobe in both the left and the right hemisphere - With the motor cortex on one side of the brain controlling the muscles on the other side of the body.
52
What is the somatosensory cortex's primary function?
Detects sensory events arising from different regions of the body
53
Where is the somatosensory cortex located in the brain?
Again is on the opposite side of the brain to the side of the body affected
Parietal lobe.
54
What is the visual cortex's primary function?
Colour / shape of movement
55
Where is the visual cortex located in the brain?
Occipital lobe of the brain.
Visual cortex spans both hemispheres, receiving information from opposite sides of the body again e.g. right hemispheres receives impulse from left retina.
Begins in retina.
56
What is the visual cortex's primary function?
concerned with hearing.
57
Where is the auditory cortex located in the brain?
Temporal lobes on both sides of brain.
Pathway begins in the cochlea in the inner ear where sound waves are converted into nerve impulses, which travel up auditory nerve.
58
Who was Broca and what did he do?
Broca's area name after Paul Broca, French neurosurgeon who treated a patient who he referred to as 'Tan' as that is the only syllable this patient could express.
59
What is Broca's area primary function?
concerned with speech.
60
Where is Broca's area located in the brain?
Posterior portion of frontal lobe - mainly left hemisphere
61
Who was Wernicke and what did he do?
Carl Wernicke, German neurologist, discovered area involving the understanding of language.
62
What is Wernicke's area primary function?
understanding of language.
63
Where is Wernicke's area located in the brain?
posterior portion of left temporal lobe.
64
What are the challenges to localisation: equipotentiality in the localisation of function.
Not all researchers agree with the view that cognitive functions are localised in the brain. Lashley (1930) believed basic motor and sensory functions were localized - but following injury the intact areas of the cortec could take over responsibility.
65
What is the support for language centres from aphasia studies in localisation of function Eval point.
Broca's and Wernicke's areas come from the discover that damage to these different areas results in different types of aphasia.
Expressive (Broca's) aphasia, an impaired ability to produce language. Most cases caused by brain damage.
Receptive (Wernicke's) aphasia impaired ability to understand language. Usually result from stroke.
66
What is communication may be more important than localisation in localisation of function. Eval point.
Research suggests what might be more important is how brain areas communicate with each other, rather than what controls each specific process. Dejerine describes a case where there was a loss of the ability to read in a patient because of damage to connection between visual cortex and Wernicke's area.
67
What is lateralisation?
Lateralisation= two halves of the brain are not exactly alike
Each hemisphere has functional specialisations i.e. neural mechanism for speech are located primarily in one half of the brain.
68
What are 2 features of the left hemisphere of the brain.
Broca + Wernicke
Language processing, analysis
Problem solving
69
What are 2 features of the right hemisphere of the brain.
Spatial comprehension
Emotions
Facial recognition
70
What section of the body does the right side of the brain control?
Left side of the body.
71
Who are split brain patients?
- A group of patients who had their Corpus Callosum is severed so that the two hemispheres are separated and don’t communicate with each other.
- This was done to control frequent and severe epileptic fits.
72
What does the corpus callosum do?
Allows info to be transferred between hemispheres.
73
What was Sperry and Gazzaniga's reseach - aim, procedure and findings.
AIM: To investigate what functions of the brain are lateralised.
PROCEDURE: Compared split brain patients to others with no hemisphere separation.
Different activities were tried with the patients including touch of objects and visual presentation of stimuli to see how the different sides perform on tasks.
FINDINGS:
LEFT visual field: they could not describe it (they often reported that there was nothing there).
RIGHT visual field: they could easily describe the picture shown to their right visual field.
74
2 evaluation points for lateralisation.
Strength:
Advantage to having a lateralised brain - each hemisphere focussing on different function. Rogers (2004) with chickens finding food and being vigilant for predators.
Increases neural processing
Evidence supporting lateralisation changes over time. Szaflarski (2006) found language became more lateralised to the left hemisphere with increasing age in children and adolescents, but after age of 25, decreased with each decade. Suggests other hemisphere compensates.
75
2 evaluation points for split brain research.
- Language may not be restricted to left hemisphere - one patient developed the capactiy to speak out of the right hemisphere.
- Limitations of split-brain research - rarely carried out nowadays, Andrewes (2001) points out many studies are presented with as few as 3 ppts. Moreover, they usually have a confounding physical disoder.
76
What is plasticity?
Refers to the brain's ability to modify its own structure and function as a result of experience.
77
Name 2 ways the brain can modify its own structure and function - plasticity
- Result of life experience
- Playing video games
- Meditation.
78
What is plasticity as a result of life experience about?
People gain new experiences, nerve pathways used frequently develop stronger connections whereas neurons that are never used, eventually die.
Developing new connections, pruning away weak ones - to adapt to environment.
79
Give the example of plasticity as a result of life experience.
Boyke et al. (2008) found evidence of brain plasticity in 60 year olds taught new skill - juggling.
80
Give the example of plasticity as a result of playing video games.
Look at Maguire (2000) study on taxi drivers.
Kuhn et al. (2014) - temporal validity - compared control groups with video game training group trained for 2 months for at least 30 mins a day at Super Mario.
Found a significant increase in grey matter in various areas of the brain in various brain areas including cortex, hippocampus. Increase not evident in control group.
81
What is functional recovery after trauma?
Look at Maguire (2000) study on taxi drivers.
1960s research found brain cells damaged/destroyed do rewire itself over time - some function regained.
82
What is neuronal unmasking in functional recovery after trauma?
Look at Maguire (2000) study on taxi drivers.
'Dormant synapses', synaptic connections which exist but function is blocked.
Normal conditions this may be ineffective because of rate of neuronal.
However, increasing the rate of input into synapses can open (unmask) dormant synapses, leading to new connections not normally activated.
83
What are stem cells in functional recovery after trauma?
Look at Maguire (2000) study on taxi drivers.
Unspecialised cells have potential to give rise to different cell types carrying out different functions.
84
What are the 2 mechanisms for recovery after trauma?
Neuronal unmasking
| Stem cells.
85
Look at Maguire (2000) study on taxi drivers.
Aim: To examine whether structural changes could be detected in the brain of people with extensive experience of spatial navigation.
Method: Structural MRI scans were obtained. 16 right-handed male London taxi drivers participated; all had been driving for more than 1.5 years. Scans of 50 healthy right-handed males who did not drive taxis were included for comparison. The mean age did not differ between the two groups.
Results: 1) Increased grey matter was found in the brains of taxi drivers compared with controls in two brain regions, the right and left hippocampi. The increased volume was found in the posterior (rear) hippocampus.
2) Changes with navigation experience – A correlation was found between the amount of time spent as a taxi driver and volume in the right posterior hippocampus.
Conclusion: The results provide evidence for structural differences between the hippocampi of London taxi drivers and control participants, therefore suggesting that extensive practice with spatial navigation affects the hippocampus.
Evaluation: Could this particular arrangement of hippocampal grey matter predispose individuals to professional dependence on navigational skills? This notion was tested directly, by examining a correlation between hippocampi volume and the amount of time spent as a taxi driver. Right posterior hippocampal volume positively correlated with the amount of time spent as a taxi driver and therefore suggests that changes in hippocampal volume are acquired.
As such, the finding indicates the possibility of local plasticity in the structure of the healthy adult human brain, as a function of increased exposure to an environmental stimulus. The results suggest that a mental map of London is stored in the posterior hippocampus and is accommodated by an increase in tissue volume.
86
Give the strength of plasticity.
Maguire (2000) study on taxi drivers in London - discovered changes in the brain could be detected as a result of extensive experience of spatial navigation. Hippocampus volume greater.
87
Give 2 evaluation points for functional recovery after trauma.
1
88
1
1
89
What is a post-mortem examination?
Used to establish the cause of death
| Establish the underlying neurobiology of a particular behaviour
90
Give an example of a post-moterm examination - how it can help study the brain.
Broca's work with patient, Tan, who displayed speech problems when alive and was subsequently found to have a lesion in the area of the brain now known as the Broca's area.
91
1 strength of a post-mortem examination.
Allow for more detailed examination of anatomical neur
92
1 weakness of a post-mortem examination.
People die in a variety of circumstances, varying stages of disease - factors that can influence post-mortem.
Limited as the person is dead - Tf researcher unable to follow up on anything from post-mortem.
93
What is a functional magnetic resonance imaging (fMRI)
technique for measuring changes in brain activity while a person performs a task.
-It does this by measuring changes in blood flow in particular areas of the brain, which indicates increased neural activity in those areas. -If a particular area of the brain becomes more active, there in an increased demand for oxygen in that area. -The brain responds to this extra demand by increasing blood flow, delivering oxygen in the red blood cells. -As a result of these changes in blood flow, researchers are able to produce maps showing which areas of the brain are involved in a particular mental activity.
94
Give 1 strength of an fMRI scan.
- Noninvasive, does not involve insertion of instruments into body.
- More objective + reliable measure than verbal reports
95
Give 1 weakness of an fMRI scan.
- Changes blood flow in brain
| - Overlooks networked nature of brain activity
96
What is an electroencephalogram (EEG)
Measures electrical activity in the brain.
Electrodes placed on scalp detect small electrical charges resulting from the activity activity of brain cells. When electrical signals from the different electrodes are graphed over a period of time - result is an EEG.
EEG data is useful for: detecting brain disorders (epilepsy)
4 basic EEG patterns are alpha, beta, delta and theta waves:
Awake but relaxed = Rhythmical Alpha. Psychologically aroused and sleep when eyes move back and forth rapidly = Low Amp / Fast frequency Beta
Delta + Theta are also sleep
97
Give 1 strength of an EEG.
- Provides a recording of the brains activity in real time, therefore a researcher can accurately measure a particular task
- It is useful in clinical diagnosis
98
Give 1 weakness of an EEG.
- It cannot reveal what is going on in deeper regions of the brain because it only detects the superficial regions
- Electrical activity can be picked up by neighbouring electrodes, therefore the EEG signal is not always that exact
99
What is an event-related potential?
Event-related potentials (ERPs) are very small voltage changes in the brain that are triggered by specific events or stimuli. ERPs are difficult to pick out from all other electrical activity being generated within the brain at a given time. To establish a specific response to a target stimulus requires many presentations of the stimulus and these responses are then averaged. Any other neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will.
100
Give 1 strength of an event-related potential (ERP).
Can measure the processing of stimuli even in the absence of a behavioural response. ERPs can record covertly
101
Give 1 weakness of an event-related potential (ERP).
- ERPs are so small and difficult to pick out from the other electrical activity in the brain. Requires a large number of trials to gain meaningful data.
- Only sufficiently strong voltage changes across the scalp are recordable.
102
How long is a circadian rhythm cycle?
24 hours, sleep and wake cycle
103
What is a circadian rhythm?
Driven by our body clocks. Found in all cells of the body and synchronised by the master circadian pacemaker - suprachiasmatic nuclei (SCN), found in hypothalamus.
104
What is the Siffre (1975) case study in circadian rhythms?
- Evidence for a 'free running' circadian rhythms comes from a series of studies by French cave explorer, Siffre.
- Siffre spent 6 months underground in a cave.
- No clocks, or natural light.
- Sleep-wake cycle intact but went from 24hrs - 25.5 hrs
- He did not know the date.
105
What is the sleep-wake cycle?
- Light and darkness are external signals that determine when we feel the need to sleep / wake up.
- Rhythm also dips and rises throughout the day so strongest sleep drive, either 2-4am or 1-3pm.
- Sleepiness in these dips is less intense if you have had enough sleep.
- Sleep also controlled by homeostatic control. Tells us need for sleep increasing because amount of energy used during wakefulness is reacting time to sleep.
106
What is the circadian clock described as and what does this mean?
Described as 'free running', maintains for 24-25 hours and even in absence of cues. Intolerant to major changes - jet lag causes clock to be out of balance.
107
What is another circadian rhythm other than the sleep-wake cycle?
Core body temperature.
108
What is the core body temperature circadian rhythm about?
Body temp rises in the morning for alertness, 4:30am = (36 degrees). Small drop in temp in afternoon between 2-4pm
Highest at 6pm = 38 degrees.
109
Give 1 weakness into Siffre's (1975) case study into circadian rhythm, sleep-wake cycle.
Use of artificial lights disrupted measurements of 'free running' circadian rhythms
Czeisler (1999) controlled light and results show circadian rhythms can vary from 13 - 65 hours.
110
Give 1 evaluation point of circadian rhythms.
- Individual differences - supported by Duffy (2001) explain why some prefer to wake up + sleep at (6am-10pm) others prefer prefer to wake and sleep later (10am-1am)
- Temp more important than light, light may be a trigger but SCN transforms info about light levels into neural messages that set body's temp. Body temp fluctuates and small changes in body temp can send a powerful signal to body clock.
111
1 strength of circadian rhythms!
Understanding circadian blood pressure rhythm helps with timing drug treatments.
112
What is an ultradian rhythm?
| Give example.
Spans a period of less than 24 hours.
| Classic example would be the 5 stages that make up a typical night's sleep.
113
What pattern does ultradian rhythm follow?
| How often does this cycle repeat?
Pattern of alternating Rapid Eye Movement (REM) and Non-Rapid Eye Movement (nREM)
Every 90-100 minutes throughout the night.
114
What does a complete ultradian cycle consist of?
| Note where REM and nREM is.
5 stages
Stages 1-2: nREM, sleep is light, can be woken, slow brain waves.
Stages 3-4: nREM, slower breating, deep brain waves, difficult to wake.
Stage 5: REM, individual is paralysed. Brain waves speed up - dreaming occurs
115
Kleitman (1969) suggested the Basic Rest Activity Cycle in ultradian rhythms. What was his study?
9 ppts over 61 nights
Brain activity monitored using EEG, woken up to report dreams
Rapid eye movement correlated to EEG patterns.
116
What is a strength of Kleitman's (1969) study?
Has been repeated.
Reseach suggests human mind can focus for a period of about 90 minutes - after 90 mins body runs out of resources.
117
Give 1 strength of ultradian research.
Shapire (1981) supports stages
Marathon runners showed longer sleep after intense physical activity. Also increased proportion in SWS, slow wave sleep - stage 3.
Technology has been developed - tracks sleep and helps individual improve it.
118
Give 1 weakness of ultradian research.
Individual differences:
| Tucker (2007) says I.D are biologically determined. Research can Tf only tell us so much
119
What are infradian rhythms?
| Give example.
Have a duration over 24 hours, could be weeks, months even annually.
eg: female menstrual cycle
120
Give an example of differences in human behaviour of a weekly rhythm in infradian rhythms.
say: EVIDENCE IS SKETCHY.
Although male testosterone levels are elavated at weekends + young couple report more sexual activity on weekends than on weekdays. But birth frequency is lower on weekends than on weekdays.
Evidence is sketchy.
121
What did McClintock (1971) find after doing research into the menstrual cycle and infradian rhythms.
-Noticed women living together tended to synchronise their periods.
-29 women (aged 20-35) with irregular period.
-Sweat samples from armpits of some of the women were collected - sterilised.
Found 68% recipients’ menstrual cycle altered and synchronised with donors.
However findings were not replicated in other studies.
122
What research has been found with Seasonal Affective Disorder (SAD) in infradian rhythms.
- Types of depression that comes and goes in sexual patterns (winter)
- At night low light levels stimulate the production of melatonin, triggering sleepiness. Symptoms include low mood, lack of activity and interest.
123
What Seasonal Affective Disorder (SAD) research has been done that supports the theory.
Infradian rhythms.
Terman (1988) found SAD was 5 times more common in New Hampshire (shorter winter days) than Florida (longer winter days).
124
Give 1 weakness of infradian rhythms.
Pheremones (secreted or excreted chemical factor that triggers a social response in members of the same species) as chemical messenger are not widely accepted
Trevathan (1993) showed lesbian couples cohabiting did not synchronise - were in optimal conditions for synchrony.
125
Are endogenous pacemakers internal/biological or external/environmental?
Internal/biological
126
Are exogenous zeitgebers internal/biological or external/environmental?
External/environmental
127
What are endogenous pacemakers?
Refers to anything whose origins are within the organism. Pacemakers are likely to be inherited allowing us to keep pace with changing cycles in environment.
128
What is the suprachiasmatic nuceli?
In mammals the main endogenous pacemakers is a cluster of nerve cells, lies in hypothalamus - important role in generating body’s circadian rhythm.
Neurons with SCN synchronise so they target neuron sites elsewhere in the body - receive correctly time - coordinated signals.
129
What is light to do with in exogenous zeitgebers?
Receptors in SCN are sensitive to light, use inference to synchronise activity of body organs + glands.
Light resets internal clock each day keeping it on 24hr cycle.
Can reset the SCN. Campbell and Murphy (1998) if you shine light on the back of participants knees, it can shift their bio-rhythms
130
What are social cues to do with in exogenous zeitgebers?
Social stimuli such as meal times can have a role in zeitgebers.
131
1 evaluation point for endogenous pacemakers.
Morgan (1955) bred hamsters so that they had circadian rhythms of 20 hours rather than 24.
W = ethical issues - LT effects
SCN neurons from abnormal hamsters were transferred to normal hamsters showing same 20hr.
suggests transplanted SCN had imposed its pattern onto recipients.
132
1 evaluation point for exogenous zeitgebers.
Using light exposure has helped to avoid jet lag.
Burgess et al. (2003) found exposure to bright light prior to an east-west flight (backward) decreased the time needed to readjust to local time on arrival.
