Biopsychology Flashcards
(165 cards)
1
Q
Where is the motor area located to?
A
Frontal lobe
2
Q
Where is the somatosensory area located to?
A
Parietal lobe
3
Q
Where is the visual area located to?
A
Occipital lobe
4
Q
Where is Wernicke’s area located?
A
Temporal lobe
5
Q
Where is Broca’s area located?
A
Frontal lobe
6
Q
Function of the motor cortex/ area?
A
Responsible for the generation of voluntary motor movements
7
Q
What are examples of circadian rhythms?
A
Sleep-wake cycle and body temperature
8
Q
What synchronises the body clocks found in all cells of the body?
A
The master circadian pacemaker
9
Q
What is the master circadian pacemaker and where is it located?
A
The suprachiasmatic nucleus (SCN) in the hypothalamus
10
Q
What is photoentrainment?
A
Light setting the body clock to the correct time
11
Q
What detects the environmental light levels? And where do they send messages to about the changes in light levels?
A
Light-sensitive cells within the eye act as brightness detectors sending messages to the SCN via the optic nerve
12
Q
What happens in the morning in the sleep-wake cycle?
A
Eyes detect light and so messages are sent via the optic nerve to the SCN
SCN sends messages to raise body temperature and blood pressure, and delay the release of hormones like melatonin from the pineal gland.
Sharpest rise in blood pressure and reduction in secretion of melatonin causes us to feel awake.
Highest levels of cortisol (in the morning), also makes us feel awake.
13
Q
What happens in the evening in the sleep-wake cycle?
A
Sun disappears, signals sent to SCN about change in light levels
SCN sends messages to make body temperature cool and sleep inducing hormones like melatonin are released
This signals it is time to sleep
14
Q
What are the two greatest dips for the circadian rhythm?
A
Between 2am and 4am, and between 1pm and 3m (post-lunch dip).
Means the greatest sleep drive usually occurs in these two dips.
Post-lunch dip may be due to a small drop in body temperature between 2pm and 4pm.
15
Q
How can dips in the circadian rhythms be intense for some people?
A
People with sufficient sleep, experience less intense sleepiness in the dips
Sleep deprived people experience more intense sleepiness dips
16
Q
What else are sleep and wakefulness determined by?
A
Homeostasis
17
Q
Why is the circadian rhythm intolerant to any major alterations?
A
Because this causes the biological clock (and the internal systems that are dependent on this) to be completely out of balance
18
Q
What did Siffre do?
A
Lived in a dark cave for 7 months
He measured his performance, heart rate, blood pressure and brain waves
19
Q
What did Siffre find?
A
His ‘natural’ sleep-cycle was 25 hours
20
Q
What is one the research method problems with Siffre’s study? (Confounding variable)
A
Artificial light was used so that Siffre could measure all of his recordings which would potentially act as a confounding variable and influence his sleep-wake cycle.
Research by Czeilser found dim artificial light could adjust circadian rhythms between 22-28 hours
21
Q
What is one the research method problems with Siffre’s study? (Aim)
A
He knew the aim of the study and so may have acted differently as a result (demand characteristics) e.g. trying to stay awake or trying to age a ‘normal’ pattern of waking and sleeping in which may not be a valid result.
22
Q
What is one the research method problems with Siffre’s study? (Case study)
A
He was an individual, may be individual differences
He found when he went back into the cave at 60 years old his sleep-wake cycle was more like 48 hours
Does not take gender and age into account
23
Q
What does Siffres study tell us?
A
Our ‘natural’ sleep-wake cycle is slightly longer than 24 hours. Light therefore seems to be the exogenous zeitgeber that entrains (affects) the cycle to make it 24 hours.
24
Q
What has shift work been found to do to circadian rhythms?
A
Causes them to desynchronise which has adverse cognitive and physiological effects
Concentration lapse at 6am
3x more as likely to suffer heart disease due to stress of adjusting sleep-wake cycles
25
What is an ultradian rhythm?
Biological rhythm that lasts less than 24 hours (more than one cycle in 24 hours)
26
What is an infradian rhythm?
Biological rhythm with a duration of over 24 hours.
27
What is the sleep cycle (sleep stages) an example of?
Ultradian rhythm
28
How long are the stages of sleep?
90-100 minutes
29
The sleep cycle: What happens in stage 1?
Light sleep
Muscle activity slows
Occasional muscle twitching
Person is easily woken
30
The sleep cycle: What happens in stage 2?
Breathing pattern and heart rate slows
Slight decrease in body temperature
31
The sleep cycle: What happens in stage 3?
Deep sleep begins
Brain begins to generate slow delta waves, which have a greater amplitude than earlier waves
32
The sleep cycle: What happens in stage 4?
Very deep sleep
Difficult to wake someone at this point
Rhythmic breathing occurs
Limited muscle activity
Brain produces delta waves
33
The sleep cycle: What happens in stage 5 (REM)?
Rapid eye movement
Brain waves speed up and dreaming occurs
Muscles relax
Heart rate increases
Breathing rapid and shallow
Body is paralysed, yet brain activity speeds up to resemble the awake brain
34
What percentage of the sleep cycle is stage 1?
4-5%
35
What percentage of the sleep cycle is stage 2?
45-55%
36
What percentage of the sleep cycle is stage 3?
4-6%
37
What percentage of the sleep cycle is stage 4?
12-15%
38
What percentage of the sleep cycle is stage 5 (REM)?
20-25%
39
Sleep Cycle: How are brainwave activity monitored?
EEG
40
What is the menstrual cycle an example of?
Infradian rhythm
41
Menstrual cycle: What is the cycle governed by?
Monthly changes in hormone levels which regulate ovulation.
42
Menstrual cycle: What period of time does the cycle refer to?
Time between the first day of the woman’s period, when the womb lining is shed, and the day before her next period.
43
Menstrual cycle: How long is the cycle?
Approximately 28 days to complete
44
Menstrual cycle: What is ovulation, when does it occur and how long does it last?
When rising levels of the hormone oestrogen cause the ovary to develop and egg and release it.
This occurs half when through the menstrual cycle when oestrogen levels are highest.
Usually lasts 16-32 hours
45
Menstrual cycle: What happens after ovulation?
The levels of the hormone progesterone increase which helps the womb grow thicker, readying the body for pregnancy
46
Menstrual cycle: What happens if pregnancy does not occur?
The egg is absorbed into the body and the womb lining comes away and leaves the body (the menstrual flow).
47
Menstrual cycle: Who did Stern and McClintock (1998) study?
Studied 29 women with irregular periods
48
Menstrual cycle: What did Stern and McClintock (1998) do?
Took samples of pheromones from 9 women, at different stages of their cycle.
On day 1, pads from the start of the menstrual cycle we’re applied to all 20 women, on day two they were given a pad from the second day of the cycle etc.
49
Menstrual cycle: How did Stern and McClintock (1998) gather pheromones and how were they given to the other women?
Via a cotton pad placed in their armpit (worn for at least 8 hours to ensure the pheromones were picked up.
The pads were then treated with alcohol and frozen, and then were rubbed on the upper lip of the other women.
50
Menstrual cycle: What did Stern and McClintock (1998) find?
68% of the women experienced changes to their menstrual cycle which brought them closer to the cycle of their ‘odour donor’.
51
Menstrual cycle: What does Stern and McClintock (1998) suggest?
Supports the endogenous infradian rhythm of the menstrual cycle.
However, suggest that it may be influenced by exogenous factors, such as the cycles of other women.
52
What is an endogenous pacemaker?
Internal body clocks that regulate many of our biological rhythms, such as the influence of the SCN on the sleep-wake cycle
53
What is an exogenous zeitgeber?
External factors that affect or entrain our biological rhythms such as the influence of light on the sleep-wake cycle
54
What is plasticity?
The brains tendency to change and adapt (functionally and structurally) as a result of experience (positive or negative), new learning or training.
55
What age does plasticity occur?
Throughout the life span; existing neural connections can change or new neural connections can be formed as a result of learning and experience
56
Does functional plasticity reduce and why?
Tends to reduce with age. The brain has a greater propensity for reorganisation in childhood as it is constantly adapting to new experiences and learning.
57
Brain plasticity: What happens during infancy?
The brain experiences a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 at 2-3 years.
58
What is synaptic pruning?
The process that as we age, rarely used connections are deleted and frequently used connections are strengthened.
59
What did Macguire et al. (2000) study?
Studied the brains of London taxi drivers. As part of their training, they have to complete a complex test called ‘the Knowledge’, which assesses their recall of the city streets and possible routes.
60
What did Mcguire et al. (2000) find?
That there was significantly more volume of grey matter in the posterior hippocampus compared to matched controls.
This is the part of the brain that is associated with the development of spatial and navigational skills in humans and other animals.
The longer they had been in the job, the more pronounced the structural difference (a positive correlation).
61
What did Mcguire et al. (2000) study suggest for theory of plasticity?
This suggests that the brain changes and adapt functionally and structurally (increases grey matter) as a result of learning and experience, supporting the theory of plasticity.
62
What did Mechelli et al. (2004) study?
Compared bilingual brains to matched monolingual controls.
63
What did Mechelli et al. (2004) find?
Found a larger parietal cortex in the brains of people who were bilingual. The experience of learning a new language led to changes in the brain’s structure (increased volume of the parietal cortex) and function (learning the new language).
64
What did Mechelli et al. (2004) suggest for theory of plasticity?
Suggest the brain changes and adapts functionally (learning new language) and structurally (increased volume of parietal cortex), supporting the theory of plasticity.
65
What is functional recovery?
The brain’s ability to redistribute or transfer functions usually performed by a damaged area(s) to other, undamaged area(s). I.e. the brain changes functionally (and sometimes structurally) as a result of the experience of trauma- making it a type of plasticity.
66
How quickly do neuroscientists suggest functional recovery occurs?
Process can occur very quickly after trauma (spontaneous recovery) and then slows down after several weeks or months. At this point the individual may require rehabilitation to aid their recovery.
67
What is neural reorganisation?
The transfer of functions to undamaged areas, which can often explain how people are able to recover from trauma.
68
What is neural regeneration?
When new neurons grow and/or new connections grow to compensate for the damaged areas where neurons are lost. This can explain how people are able to recover from trauma. Reformation of blood vessels support the new connections made.
69
Why is functional recovery easier when we are younger?
Because the brain is still maturing, recovery from trauma is more likely because maturing brains are constantly adapting to experiences and learning
70
How else does functional plasticity aid recovery?
Plasticity allows the brain to cope better with ‘indirect’ effects of brain damage e.g. swelling, haemorrhages that may occur after road accidents, effects of brain damage from inadequate blood supply following a stroke.
71
Functional recovery: what else can enhance recovery?
Brain stimulation of the opposite hemisphere to the trauma, physiotherapy etc.
72
What is the endocrine system?
A network of glands throughout the body that manufacture and secrete chemical messengers called hormones. Hormones are required to regulate bodily functions.
Provides a chemical system of communication for the body via the bloodstream. A required amount of specific hormone is released from an endocrine gland which regulate physiological processes of the human body e.g. growth
73
How is the endocrine system different from the nervous system?
Endocrine system uses blood vessels to deliver hormone to target sites in the body rather than nerves to transmit information.
Endocrine system acts much more slowly than the nervous system, but has more widespread and powerful effects
74
What are endocrine glands?
A specialist group of cells within the endocrine system. Their function is to produce and secrete hormones, chemical substances that regulate the activity of cells or organs in the body. Each gland produces different hormones, which regulate the activity of tissues and organs in the body.
75
What are hormones?
Chemical messages that travel through the bloodstream and are carried to target sites throughout the body. Hormones come into contact with the most cells in the body, but they only affect a limited number of cells called target cells.
76
How do hormones stimulate certain cells in the body but not others?
Target cells respond to particular hormones because they have receptors for that hormone. When enough receptor sites are stimulated by hormones, this results in a physiological reaction in the target cell.
77
How is the endocrine system regulated?
Regulated by feedback. One set of signals stimulates the release of hormones. As the levels of that hormone rise in the bloodstream a second set of signals slows down the secretion of that hormone. This results in stable concentrations of hormones circulating in the bloodstream.
78
What is the key roles of the pituitary gland?
Master gland that regulates many of the body’s functions
Produces hormones that control the release of hormones from other glands
79
What hormones does the pituitary gland release and what are the effects on behaviour?
ACTH- when released in the response to stress, it stimulates the adrenal glands to release cortisol.
FSH and LH- In females it stimulates the ovaries to produce oestrogen and progesterone. In males, it stimulates the testes to produce testosterone
Oxytocin- It stimulates the contraction of the womb in childbirth and is important for mother-infant bonding.
80
What are the key roles of the adrenal gland?
Causes physiological changes associated with arousal and prepares the body for fight or flight.
Supports bodily functions, such as cardiovascular and anti-inflammatory functions.
81
What hormones does the adrenal gland produce and what are their effects on behaviour?
Cortisol- released in response to stress. It affects glucose metabolism, lowers sensitivity to pain and suppresses to immune system.
Adrenaline and noradrenaline- helps the body respond to stressful situations e.g. increasing heart rate, increasing blood flow to the muscle and brain and converting glycogen to glucose
82
What is the key role of the ovaries?
Production of eggs and female sex hormone
83
What hormones do the ovaries produce and what are their effects on behaviour?
Oestrogen- female reproductive function
Progesterone- associated with increased sensitivity to social cues (which would be important in pregnancy)
84
What is the key role of the testes?
Produces sperm and male sex hormones
85
What hormones do the testes produce and what are their effects on behaviour?
Testosterone-
Important for sex drive, sperm production and muscle strength, and is associated with general health and well-being in men.
Also important for the development of male characteristics such as facial hair, deepening voice, and growth spurt
86
When does the fight or flight response occur?
When the body prepares itself for defending/ attacking (fight) or running away (flight).
87
Fight or flight response: What does it involve?
Changes in the nervous system and the secretion of hormones that are necessary to sustain arousal
88
Fight or flight response: Why did it evolve?
As a survival mechanisms, enabling humans and animals to react quickly to life threatening situations
89
Fight or flight response: What happens after a threat/ stressor is perceived?
The hypothalamus prepares the body for action by triggering the sympathetic nervous system .
90
Fight or flight response: What’s state does the body switch from and to what?
Switches from the parasympathetic state to the sympathetic state. Which begins the process of preparing the body for rapid action necessary for fight or flight.
91
Fight or flight response: What does the sympathetic nervous system do?
Sends a signal to the adrenal medulla, and the adrenal medulla releases adrenaline.
92
Fight or flight response: What are the effects of adrenaline being released on the body?
Range of effects that prepare the body for action:
Heart rate, respiration and sweating increases, oxygen supply to skeletal muscles and the brain increase, blood vessels are constricted,blood is diverted away from the skin, kidneys and digestive system.
93
Fight or flight response: What happens once the threat has passed?
The parasympathetic nervous system is activated. The body returns to its resting state e.g. heart rate and blood pressure are reduced and digestion begins again (rest and digest)
94
Fight or flight response: What is the body’s priority after fight of flight?
Energy conservation rather than expenditure
95
Fight or flight response: How is the fight or flight potentially useful?
The physiological responses associated with fight or flight may be adaptive for a stress response that required energetic behaviour e.g. feeling from a lion or moving out of the path of an oncoming car.
96
Fight or flight response: What are modern day stressors? And why is this a problem?
Stressors of modern day life rarely require such physical activity (e.g. worrying about exams). The problem for modern humans is when the stress response is repeatedly activated. The increased blood pressure can lead to physical damage to the blood vessels and eventually heart disease.
97
Fight or flight response: Modern stressors- what does that suggest about the fight of flight response?
Suggests that the response may no longer be adaptive for stressors we face today. However it could be argued that it is still adaptive for some stressors of threats we face today e.g. narrowly avoiding being hit by a car
98
Fight or flight response: What has been suggested to be the first stage of fight or flight instead?
To avoid confrontation. Some psychologists suggest that before responding with attacking or running away, most animals (including humans) typically display a ‘freeze’ response. This is essentially a ‘stop, look and listen’ response, where the animal is hyper-vigilant (alert to the slightest signs of danger).
99
Fight or flight response: What does the freeze response suggest about the fight or flight response?
This would have been adaptive for humans as it focuses attention and makes them look for new information in order to make the best response for that particular threat. Consequently, the fight or flight may not be a complete explanation of our response to stress.
100
Fight or flight response: What did Speisman et al (1964) do?
Asked students to watch a primitive and gruesome medical procedure (initiation rites involving genital mutilation) on film while heart rates were monitored.
101
Fight or flight response: What did Speisman et al (1964) tell participants?
Told some participants that the initiation rites were voluntary and joyful rite of passage (because it signalled the arrival of manhood).
Other participants were told the experience was traumatic and painful.
102
Fight or flight response: What did Speisman et al (1964) find?
They found participants in first group heart rates decreased, but heart rates of those in the second group increased.
103
Fight or flight response: What did Speisman et al’s (1964) study suggest about the fight of flight response?
Suggests that humans aren’t passive in the face of stressors or threats like the fight or flight response theory would assume. Cognitions (thinking whether the stressor is a threat or not) are also important and therefore the theory is a limited explanation of our response to stress.
104
Fight or flight response: What were men and woman’s roles in our evolutionary past?
Had different roles in society
Men would have been hunters, so the fight or flight response would have been appropriate.
Women would have been gatherers whose primary role was to protect themselves and their young.
105
Fight or flight response: What does woman’s evolutionary role suggest?
Women may have a completely different response system for coping to stress because of their role differences.
Fleeing too readily after any sign of danger would put their offspring at risk. It would have been more adaptive for women to have a ‘tend and befriend’ response, in which a threat is met with tending to their offspring and befriending other females to form protective alliances.
106
Fight or flight response: What have studies shown about females response to stress?
They release oxytocin when under stress, and this suppresses the fight or flight response
107
Fight or flight response: What do the differences in men and woman’s roles in society suggest about the fight or flight response?
That there is a male bias and the assumption that fight or flight is a valid explanation in all humans is a reflection of the bias towards male psychology.
108
Functional recovery: What did Schneider et al.(2014) find?
Found that patients with the equivalent of a collage education are 7 times more likely than those who didn’t finish high school to be disability-free one year after a moderate to serve brain injury.
109
Functional recovery: What does Schneider et al.(2014) findings suggest about functional recovery after trauma?
Suggests that education attainment may influence how well the brain functionally adapts after injury and therefore acts as a moderating factor meaning that we cannot see simple cause and effect.
110
Functional recovery: What real world application?
Understanding the processes involved in plasticity has led to the field of neurorehabilitation.
111
Functional recovery: What does the real world application show?
Following illness or injury the brain, spontaneous recovery tends to slow down after a number of weeks. Therefore, forms of physical therapy may be required to maintain improvements in functioning.
112
Functional recovery: What does the real world application techniques may be used?
Techniques may include movement therapy and electrical stimulation of the brain to counter the deficits in motor and/or cognitive functioning that may be experienced following a stroke for example.
113
Functional recovery: What does the real world application suggest about functional recovery after trauma?
Suggests that although the brain may have the capacity to ‘fix’ itself to a point as a result of plasticity, the processes require further intervention if it is to be completely successful. However, this has led to the development of therapies and interventions to ensure that functional recovery is completely successful.
114
Plasticity: Two studies that are supporting evidence?
Macguire et al (2000)- Taxi driver study
Mechelli et al (2004)- Bilingual brain vs monolingual brain
115
Plasticity: What did Bezzola et al. Do?
Demonstrated how 40 hours of golf training produced changes in neural representation of movement in partisans aged 40-60 years old.
116
Plasticity: What did Bezzola et al. Find?
Using fMRI, researchers observed that there was reduced motor cortex activity in the novice golfers compared to a control group, suggesting more efficient neural representations after training.
117
Plasticity: What did Bezzola et al. Study suggest for brain plasticity?
Suggests that neural plasticity continues throughout the lifespan. Provides further evidence to show the brain is highly plastic.
118
What happens if the motor cortex becomes damaged?
May result in a loss of control over fine motor movements
119
What is the function of the somatosensory cortex?
Region of the brain that processes input from sensory receptors in the body that are sensitive to touch I.e. it processes sensory information such as touch.
120
Somatosensory cortex: What indicates the body parts sensitivity?
The amount of the somatosensory cortex area devoted to that body part e.g. receptors for our face and hands occupy over half of the somatosensory cortex and so are very sensitive.
121
What happens if the somatosensory cortex is damaged?
Can lead to numbness and sometimes parathesia (tingling sensations in parts of the body).
122
What is the function of the visual centre?
Receives and processes visual information
123
Visual centres: Where does visual processing begin?
In the retina, at the back of the eye, where light enters and strokes photoreceptors called rods and cones.
Action potentials from the retina are then transmitted to the brain via the optic nerve.
Most action potentials terminate in the thalamus, which is part of the brain that acts like a relay station, passing information on to the visual cortex.
124
Why are there several different areas in the visual cortex?
Because each area processes different types of visual information such as colour, shape or movement.
125
What happens if the visual centre (cortex) is damaged?
Can lead to vision and perception problems, mostly blindness and visual hallucinations.
126
What is the function of the auditory centre?
Concerned with the analysis of speech based I.e. hearing.
127
Auditory centre: Where does the auditory pathway begin?
In the cochlea in the inner ear, where sound waves are converted to action potentials, which travel via the auditory nerve to the auditory cortex in the brain.
128
What happens if there is damage to the auditory centre?
May produce partial hearing loss; the more extensive the more extensive the loss.
129
What hemisphere are language centres usually lateralised to?
The left hemisphere
130
What is Broca’s area named after?
Paul Broca’s who treated a patient known as ‘Tan’ because that was the only syllable he could express. Tan was able to understand spoken language, but was unable to speak, nor express his thoughts in writing.
131
Who else did Broca’s study?
Studied other patients with similar language deficits to Tan, along with lesions in their left frontal hemisphere. Patients with damage to the right hemisphere did not have the same language problems.
132
What is the function of Broca’s area?
Critical for speech production
133
What happens if Broca’s area is damaged?
Called Broca’s aphasia
These people are often only able to speak in short meaningful sentences which take great effort (they are slow and laborious). The speech lacks fluency as there is a difficulty with words that help sentences to function (e.g. ‘it’, ‘the’ etc).
134
Who discovered Wernicke’s area?
Carl Wernicke
135
What is the function of Wernicke’s area?
Involved in understanding language (I.e. the interpretation of speech).
136
What happens if Wernicke’s area is damaged?
Wernicke’s aphasia
Can speak, but unable to understand language, so the speech that they produced was fluent but meaningless. They often produce nonsense words (called neologisms) as part of the content of their speech.
137
Localisation of function: What happened to Phineas Gage?
Survived a metre-length pole passing through his left cheek, left eye and exiting his skull. The damage to his frontal lobe left a mark on his personality-he turned from a calm reserved person to someone who was quick-tempered and rude.
138
Localisation of function: What does Phineas Gage tell us about localisation of function?
Suggests that the frontal lobe may be responsible for regulating mood, supporting localisation theory. However, this is a case study, so it cannot provide particularly strong support for localisation theory as it lacks external validity in that Gage may be a unique case.
139
Localisation of function: What did Lashley do?
Removed areas of the cortex (10-50%) in rats that were learning a maze.
140
Localisation of function: What did Lashley find?
No area was proven to be more important than any other in terms of the rats’ ability to learn the maze.
141
Localisation of function: What does Lashley’s study on rats suggest about localisation of function theory?
The process of learning appeared to require every part of the cortex, rather than being confined to one particular area. This seems to suggest that learning is too complex to be localised, and requires the involvement of the whole brain. Therefore, processes involved in learning may be distributed in a more holistic way in the brain.
142
Localisation of function: What does Lashley’s study on rats suggest about localisation of function theory- counter point?
However, we should be cautious in drawing conclusions related to human learning from this study as the participants were rats and therefore they may learn differently to humans.
143
Localisation of function: What did a French neurologist find?
Found that the loss of the ability to read resulted from damage to the connection between the visual cortex and Wernicke’s area.
144
Localisation of function: What do the French neurologist’s findings tell us about localisation of function?
Suggests that how brain areas communicate with each other may be more important than which specific brain regions control a particular cognitive process.
Wernicke claimed that although different regions of the brain had different specialist functions, they are interdependent in the sense they that in order to work they must interact with each other.
Damage to the connection between any two points in a process results in impairments that resemble damage to the localised brain region associated with that particular function.
145
Localisation of function: What was found about people with Broca’s aphasia?
They have an impaired ability to produce language and in most cases thus was caused by damage in their Broca’s areas.
146
Localisation of function: What was found about people with Wernicke’s aphasia?
Found to have an impaired ability to understand language and is usually the result of damage in Wernicke’s area.
147
Endogenous pacemakers: What is the role?
The endogenous pacemaker SCN receives information about light levels via the optic nerve. This happen even when our eyes are closed, because light penetrates the eyelids. The SCN then sends information about light to the pineal gland to instruct it to increase or decrease melatonin secretion.
148
Exogenous zeitgeber: What is the role?
If our biological clock is running slow (e.g. the sun rises earlier than on the previous day), then morning light (exogenous zeitgeber) automatically adjust the clock, putting its rhythm back in step with the outside world.
149
Endogenous pacemakers and exogenous zeitgebers: What is it difficult to do?
Very difficult to seperate the relative importance of endogenous pacemakers and exogenous zeitgebers as they are so closely linked.
150
Endogenous pacemakers: What did DeCoursey et al (2000) do?
Destroyed the SCN connections in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80 days.
151
Endogenous pacemakers: What did DeCoursey et al (2000) find?
The sleep-wake cycle of the chipmunks disappeared and by the end of the study a significant proportion of them has been killed by predators (presumably because they were awake and vulnerable to attack when they should have been asleep).
152
Endogenous pacemakers: What does DeCoursey et al (2000) study say about endogenous pacemakers?
Supports that the SCN is important in establishing and maintain the circadian rhythm of the sleep-wake cycle because when it’s connections are destroyed, the sleep-wake cycle disappears, implying that this is its role.
153
Exogenous zeitgeber: What did Campbell and Murphy (1998) do?
They demonstrated that light may be detected by skin receptor sites on the body 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’ usual sleep-wake cycle of up to 3 hours in some cases.
154
Exogenous zeitgeber: What did Campbell and Murphy (1998) suggest about exogenous zeitgebers?
Supports that light affects (entrains) the sleep-wake cycle as participants’ cycles were adjusted by up to 3 hours by exposure to light. It seems that light may not even need to be shone in the eyes to exert its influence, and therefore suggests that the theory is valid.
155
Exogenous zeitgeber: What are social stimuli and what might they have a role as?
Mealtimes and social activities, may also have a role as zeitgebers.
156
Exogenous zeitgeber: How are social stimuli entrained in infants?
In human infants, the initial sleep-wake cycle is pretty much random. At about 6 weeks of age, the circadian rhythms begin and adapt about 16 weeks, most babies are entrained. The schedules imposed by parents are likely to be key influence e.g. adult-determined mealtimes and bedtimes.
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Exogenous zeitgebers: What is the weakness of Campbell and Murphy’s study?
The results are yet to be replicated. Other psychologists have also been critical of the manner in which the study was conducted. They have suggested that there may have been some limited light exposure to the participants’ eyes which acted as a major confounding variable.
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Exogenous zeitgebers: What does the weakness of Campbell and Murphy’s study suggest about exogenous zeitgebers?
This suggests that the results may not be internally valid and as such, we cannot strongly support the role of light as an exogenous zeitgeber via the skin form the research.
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Endogenous pacemakers: What is the weakness of DeCoursey et al’s study?
There is a huge problem in generalising the results of animal studies (chipmunks) of the sleep-wake cycle to humans. Additionally, the ethical issues of the study are subject to criticism. The animals were exposed to considerable harm, and subsequent risk when returned to their natural habitat.
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Endogenous pacemakers: What does the weakness of DeCoursey et al’s study suggest about endogenous pacemaker?
Whether what we learn from such investigations such as these justifies the aversive procedures involved is a matter of debate. Regardless, we cannot be certain if the results from an animal study are completely externally valid and so from the research, we can’t strongly support the role of the SCN as an endogenous pacemaker.
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Hemispheric lateralisation: What is it?
Idea that the two halves (hemispheres) of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by (specialised to) one hemisphere rather than the other I.e. they have functional specialisations.
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Hemispheric lateralisation: What is the corpus callosum?
A thick bundle of nerve which connects the two hemispheres of the brain. It allows the two sides of the brain to communicate with each other so that the whole brain can work as one complete organ I.e information received by one hemisphere can be sent to the other hemisphere.
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Hemispheric lateralisation: What is the left hemisphere responsible for?
Control of the right hand, right visual field, speech, analytical tasks, logical thinking, understanding spoken and written language
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Hemispheric lateralisation: What is the right hemisphere responsible for?
Control of the left hand, left visual field, musical ability, drawing, emotional content of language, creativity, spatial awareness, recognising faces
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Hemispheric lateralisation: Who were the participants in Sperry’s research?
11 individuals who had undergone the same surgical procedure in which the corpus callosum (and other tissues which connect the two hemispheres) was cut in order to control frequent and serve epileptic seizures.
