Topic 6 - Biopsychology Flashcards
What is the nervous system?
Primary internal communication system, a specialised network of cells in our body.
What does the central nervous system do?
The central nervous system receives information from the senses and controls the behaviour and regulation of the body’s psychological processes. The brain receives information from sensory receptors and sends messages to muscles and glands. It is the centre of all conscious awareness and is divided into different lobes with different functions. It contains the cerebrum which makes up about 85% of the total mass.
What are the 2 components of the CNS?
Brain and spinal cord.
What is the thalamus?
Concerned with relaying sensory information from the brainstem to the cortex.
What is the hypothalamus?
Controls basic functions such as hunger, thirst, sexual behaviour; also controls the pituitary gland.
What do the cerebral hemispheres control?
Higher level cognitive and emotional processes: The limbic system is involved in learning, memory and emotions.
What are the basal ganglia involved in?
Involved in motor activities and movement.
What is the neocortex/cerebral cortex involved in?
Involved with planning, problem-solving, language, consciousness and personality.
What is the spinal cord responsible for?
An extension of the brain that is responsible for reflex actions. It allows the brain to monitor processes such as breathing and to control voluntary movements.
What is the hindbrain made up of?
(Pons, medulla, cerebellum) 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.
What does the cerebellum control?
Movement and motor coordination.
What is the peripheral nervous system?
The portion of the nervous system that is outside the brain and spinal cord. The primary function of the peripheral nervous system is to connect the brain and spinal cord to the rest of the body and the external environment.
What does the peripheral nervous system do?
Transmits information to and from the CNS. This is accomplished through nerves that carry information from sensory receptors in the eyes, ears, skin, nose and tongue, as well as stretch receptors and nociceptors in muscles, glands and other internal organs.
How many spinal nerves is the PNS made up of?
31
What are the two subsections peripheral nervous system?
Autonomic NS and Somatic NS.
What does the SNS do?
Controls voluntary movements, transmits and receives messages from the senses and is involved in reflex actions without the involvement of the CNS so the reflex can occur very quickly.
It connects the central nervous system with the senses and is composed of: Sensory nerve pathways bring information to the CNS from sensory receptors, dealing with touch, pain, pressure, temperature etc.
What does the ANS do?
Regulates involuntary actions such as bodily arousal (how ‘excited’ or relaxed we are), body temperature, homeostasis, heart rate, digestion and blood pressure.
What are the 2 parts of the ANS?
The sympathetic nervous system and the parasympathetic nervous system.
What does the sympathetic nervous system do?
That is involved in responses which help us deal with emergencies. It slows bodily processes that are less important in emergencies such as digestion. The sympathetic ANS leads to increased arousal: e.g. increase in heart rate and blood pressure, pupil dilation, reduction in digestion and salivation.
What does the parasympathetic nervous system do?
That relaxes the individual once the emergency has passed (e.g. slows the heart rate down and reduces blood pressure) and conserves the body’s natural activity by decreasing activity/maintaining it. The parasympathetic ANS leads to decreased arousal.
What are the sensory neurons responsible for?
Convey information about sensory stimuli: vision, touch, taste, etc. towards the brain.
What are the motor neurons responsible for?
Convey instructions for physical operations: e.g. release of hormones from glands, muscle movement, digestion, etc.
What are the relay neurons responsible for?
Pass messages between motor and sensory neurons.
What is the endocrine system?
Hormones are chemical messengers secreted from structures (glands) in the body which pass through the bloodstream to cause changes in our body or behaviour. The network of glands is called the endocrine system.
Give the hormone and function of the thyroid gland.
Thyroxine - regulates metabolic rate and protein synthesis.
Give the hormone and function of the adrenal medulla gland.
Adrenaline and noradrenaline - fight or flight response: increased heart rate, blood pressure, release of glucose and fats (for energy).
Give the hormone and function of the adrenal cortex gland.
Corticosteroids - release of glucose and fats for energy; suppression of the immune system.
Give the hormone and function of the testes.
Testosterone - male sexual characteristics, muscle mass.
Give the hormone and function of the ovaries.
Oestrogen - female sexual characteristics, menstruation, pregnancy.
Give the hormone and function of the pineal gland.
Melatonin - sleep-wake cycle.
Give the hormone and function of the pituitary gland.
The pituitary gland is the master gland, and controls release of hormones from many of the glands described above. The pituitary is divided into the anterior and posterior.
Give the function of atch.
Stimulates release of corticosteroids during flight-flight response.
Give the function of oxytocin.
Uterine contractions during childbirth.
Give the function of the growth hormone.
Cell growth and multiplication.
Give the function of vasopressin.
Regulates water balance.
Give the function of prolactin.
Stimulates production of milk from mammary glands (breasts).
What is the fight or flight response?
The fight or flight response is a sequence of activity within the body that is triggered when the body prepares itself for defending or attacking (fight) or running away to safety (flight).
What are the 2 major systems that are involved in the fight or flight?
The pituitary-adrenal system and the sympathomedullary pathway.
What is sympathomadullary pathway responsible for?
Deals with acute (short-term, immediate) stressors such as personal attack.
What is the pituitary-adrenal system responsible for?
Deals with chronic (long-term, on-going) stressors such as a stressful job.
What affect does adrenaline have on the sympathetic and parasympathetic nervous system?
Arousal of the sympathetic nervous system and reduced activity in the parasympathetic nervous system.
Once the threat is over, what happens?
The parasympathetic branch takes control and brings the body back into a balanced state. No ill effects are experienced from the short-term response to stress, and it further has survival value in an evolutionary context.
Explain in depth what the hypothalamic pituitary-adrenal system does.
The stressor activates the hypothalamic pituitary axis the hypothalamus stimulates the pituitary gland the pituitary gland secretes adrenocorticotropic hormone (acth) acth stimulates the adrenal glands to produce the hormone corticosteroid the adrenal cortex releases stress hormones called cortisol. This has a number of functions including releasing stored glucose from the liver (for energy) and controlling swelling after injury. The immune system is suppressed while this happens. Adequate and steady blood sugar levels help person to cope with prolonged stressor and helps the body to return to normal.
What happens when an electrical signal reaches the axon terminals?
Molecules of neurotransmitters are released across the synaptic gap/synapse (the gap separating one neuron from another) and then attach to post-synaptic receptors on the adjacent neuron.
This will then trigger an electrical impulse in the adjacent cell. During synaptic transmission, the action potential (an electrical impulse) triggers the synaptic vesicles of the pre-synaptic neuron to release neurotransmitters.
These neurotransmitters diffuse across the synaptic gap (the gap between the pre and postsynaptic neurons) and bind to specialised receptor sites on the post-synaptic neuron.
Define an excitatory neurotransmitter.
Make a nerve impulse more likely to be triggered: for example, dopamine or serotonin which produce states of excitement/activity in the nervous system and in our mental state/behaviour.
Define an inhibitory neurotransmitter.
Make a nerve impulse less likely to be triggered: for example, gaba calms activity in the nervous system and produces states of relaxation (as with anti-anxiety medication such as valium).
What does the localisation theory state?
The theory that different areas of the brain are responsible for different behaviours, processes or activities. It contrasts with the holistic theory of the brain. If a certain area of the brain becomes damaged, the function associated with that area will also be affected. The link between brain structures and their functions (e.g. Language, memory, etc.) Is referred to as brain localisation.
What does the motor cortex control?
Voluntary movement. Different areas of the motor cortex control 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, etc.)
What is visual centre responsible for?
Processing of 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.
What is auditory centre responsible for?
Processing of 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 (which decodes duration and intensity of sound) then to the auditory cortex which recognises the sound and may form an appropriate response to that sound.
What is broca’s area?
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 (damage) 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).
What is wernicke’s area?
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).
Explain a piece of supporting research for the localisation theory.
Phineas gage was in an accident which caused him to lose part of his frontal lobe which altered his personality – the frontal lobe may play a role in mood regulation therefore localisation theory is correct.
Give two weaknesses of the theory of localisation.
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 and decision-making) 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.
What is hemispheric lateralisation?
Concerns the fact that the brain’s 2 hemispheres are not exactly alike and have different specialisms. For example, the left hemisphere is mainly concerned with speech and language and the right with visual-motor tasks. Broca (1861) found that damage to the left hemisphere led to impaired language but damage to the same area on the right hemisphere did not.
The brain’s 2 hemispheres are connected by a bundle of nerve fibres – the corpus callosum. What does this do?
Allows information received by one hemisphere to be transferred to the other hemisphere. Investigations into the corpus callosum began when doctors severed patients’ corpus callosum in an attempt to prevent violent epileptic seizures.
What did sperry test and in what year?
Sperry (1968) tested such split-brain patients to assess the abilities of separated brain hemispheres.
What was sperry’s aim?
To assess the abilities of separated brain hemispheres.
Describe the procedure and findings of sperry’s experiment.
Procedure: participants sat in front of a board with a horizontal row of lights 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.
Findings: when their right eye was covered, and the lights were flashed to the left side of their visual field they claimed not to have seen any lights at all. However, when asked to point at which lights had lit up, they could do.
Give two weaknesses of split-brain research and hemispheric lateralisation.
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 did 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 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.
Give two strengths of split-brain research and hemispheric lateralisation.
Brain lateralisation is assumed to be evolutionarily adaptive as devoting just one hemisphere of the brain to tasks leaves the other hemisphere free to handle other tasks. For example, in chickens, brain lateralisation allows birds to use one hemisphere for locating food, the other hemisphere to watch for predators. Thus, brain lateralisation allows for cognitive multitasking which would increase chances of survival.
Individuals with high level mathematical skills tend to have superior right hemisphere abilities, are more likely to be left-handed, and are more likely to suffer allergies and other immune system health problems. This suggests a relationship between brain lateralisation and the immune system.
What is plasticity?
The brain’s tendency to change and adapt (functionally and physically) as a result of experience and new learning.
What happens to the brain when learning and experiencing new things?
Learning and new experiences cause new neural pathways to strengthen whereas neural pathways which are used infrequently become weak and eventually die. Thus, brains adapt to changed environments and experiences.
What did boyke find in 2008?
Found that even at 60+, learning of a new skill (juggling) resulted in increased neural growth in the visual cortex.
What did kuhn find in 2014?
Found that playing video games for 30+ minutes per day resulted in increased brain matter in the cortex, hippocampus and cerebellum. Thus, the complex cognitive demands involved in mastering a video game caused the formation of new synaptic connections in brain sites controlling spatial navigation, planning, decision-making, etc.
What did Davidson find in 2004?
Matched 8 experienced practitioners of tibetan buddhist meditation against 10 participants with no meditation experience. Levels of gamma brain waves were far higher in the experienced meditation group both before and during meditation. Gamma waves are associated with the coordination of neural activity in the brain. This implies that meditation can increase brain plasticity and cause permanent and positive changes to the brain.
What did Kempermann find in 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.
When studying the brains of london taxi drivers, what was found?
MRI scans revealed that the posterior portion of the hippocampus was significantly larger than a control group, and size of difference was positively correlated with amount of time spent as a taxi driver (i.e. Greater demands on memory = more neurons in this portion of hippocampus).
What is functional recovery?
The idea that following physical injury or other forms of trauma, unaffected areas of the brain can adapt to compensate for those that are damaged.
Case studies of stroke victims have shown what?
Case studies of stroke 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 brain sites taking over the functions of damaged brain sites. Thus, neurons next to damaged brain sites can take over at least some of the functions that have been lost.
Functional recovery is an effect of brain plasticity which is thought to operate in 2 main ways. Name the two ways.
Neuronal unmasking and stem cells are unspecialised cells which can become specialised to carry out different types of tasks.
What did wall discover about neuronal unmasking in 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.
Describe the correlation between functional recovery and age? Explain why.
There is a negative correlation between functional recovery and age: i.e. Young people have a high ability to recover which declines as we age. Level of education (associated with a more active, neurologically well-connected brain) is positively correlated with speed of recovery from traumatic brain injuries. Schneider found that patients with a college education were x7 times more likely to than those who did not finish college to recover from their disability after 1 year.
What is a fMRI?
Functional magnetic resonance imaging (fmri): a brain scanner which measures increased blood flow to brain sites when individuals are asked to perform cognitive/physical tasks. Increased blood flow indicates increased demand for oxygen in that area. This produces 3d images showing which parts of the brain are involved in a particular mental process, important for our understanding of localisation of function. Thus, fmri can help build up a map of brain localisation.
Give two strengths of fMRIs.
- Non-invasive – no insertion of instruments unlike pet and no exposure to radiation
- Beneficial to the economy as there is no recovery time so people don’t have to be off work.
Give four weaknesses of fMRIs.
- Fmri only measures blood flow – it cannot home in on the activity of individual neurons therefore it’s hard to tell exactly what brain activity is being represented on the screen
- High likelihood that the findings will be misinterpreted as it doesn’t show activity like eeg/erp.
- Fmri may overlook the interconnectivity of 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.
- Expensive – other neuroimaging techniques such as eeg may be cheaper, and it can only capture a clear image if the person stays still – may not be worthwhile for the nhs to fund.
What are EEG’s?
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 states (e.g. Waking vs. Asleep). Eeg readings can detect epilepsy and alzheimer’s. 4 basic brain wave patterns are (i) alpha – awake and relaxed, (ii) beta – awake and highly aroused or in rem (rapid eye movement sleep), (iii) delta – deep sleep, (iv) theta – light sleep.
Give four strengths of EEG’s.
- Records brain activity over time and can, therefore, monitor changes as a person switch from task to task or one state to another (e.g. Falling asleep).
- Eegs have medical applications in diagnosing disorders such as epilepsy and alzheimer’s.
- Non-invasive - no insertion of instruments unlike pet and no exposure to radiation
- Eegs are virtually risk free and are avoidant of any danger to the brain itself.
- Cheaper than fmri thus making them more available
- Psychologists can gather more data on the functioning of the human brain thus contributing to our understanding of different psychological phenomena.
Give four weaknesses of eeg’s.
- Eegs only monitor electrical activity in outer layers of the brain, therefore, cannot reveal electrical activity in deeper brain sites.
- Not highly accurate – electrical activity detected in several regions of the brains simultaneously – very hard to pinpoint exactly which area is producing this activity, therefore cannot distinguish differences in activity between 2 closely adjacent areas.
- Uncomfortable – hard for the patients as electrodes are attached to their head
- Could result in an unrepresentative reading as the patient’s discomfort could trigger cognitive responses to the real time situation.
What are ERP’s?
Event-related potentials: very small voltage changes in the brain triggered by specific events or stimuli which are measured using an eeg. 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 erp for that stimulus. Erps are of 2 types: (i) sensory erps - those that occur within 100 milliseconds of stimulus presentation; (ii) cognitive erps – those that occur 100 milliseconds or more after stimulus presentation. Sensory erps indicate the brain’s 1st recognition of a stimulus. Cognitive erps represent information processing and evaluation of the stimulus.
Give three strengths of ERP’s.
- Erps provide a continuous measure of neural activity in response to a stimulus. Therefore, changes to the stimulus can be directly recorded: e.g. If a blue coloured slide turned green.
- Derived from eeg – excellent temporal resolution compared to fmri – much more specificity has led to their widespread use in the measurement of cognitive functions and deficits.
- Non-invasive - no insertion of instruments unlike pet and no exposure to radiation – virtually risk free and is avoidant of any danger to the brain itself.
Give three weaknesses of ERP’s.
- Erps only monitor electrical activity in outer layers of the brain, therefore, cannot reveal electrical activity in deeper brain sites.
- Extraneous stimuli must be eliminated in order to collect pure data, the participant may react to background noise or a difference in temperature – for experiments where these variables can’t be controlled, it’s difficult to draw conclusions.
- Lack of standardisation in methodology between studies – different groups will use varying averages on what neural activity they decide to filter out – hard to replicate experiments and confirm findings in a peer review study.
What are post-mortem examinations?
Brains from dead individuals who displayed cognitive abnormalities whilst alive can be dissected to check for structural abnormalities/damage: e.g. Broca’s area was discovered after dissections of patients who displayed speech abnormalities, and hm’s (memory topic) inability to store new memories was linked to lesions in his hippocampus. Neurological abnormalities have been linked to depression, schizophrenia, anti-social personality disorder, etc.
Give four strengths of post-mortem examinations.
- Allow for detailed examinations and measurement of deep brain structures (e.g. The hypothalamus) not measurable by brain scans.
- Brain tissue can be examined in detail – deep structures of the brain can be investigated after death – pm is more appropriate than eeg or erp when examining any brain structure other than the neocortex.
- Highly applicable – broca and wernicke both relied on postmortem studies in establishing links between language, brain and behaviour decades before neuroimaging ever became a possibility
- Evidence has improved medical knowledge and less money can be used by the nhs on less efficient techniques which generates a positive impact on the economy.
Give four weaknesses of post-mortem examinations.
- The issue of causation – the deficit a patient displays during their lifetime may not be linked to the deficits found in the brain, they may be the result of another illness
- Psychologists are unable to conclude that the deficit is caused by the damage found in the brain. 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.
- Ethical issues – deceased people are not able to provide informed consent and there will be problems with replicability because future ethical guidelines will be stricter.
What are the three types of biological rhythms?
- Circadian rhythms: follow a 24-hour cycle: e.g. The sleep-waking cycle
- Ultradian rhythms: occur more than once a day: e.g. The cycles of rem and nrem sleep in a single night’s sleep
- Infradian rhythms: occur less than once a day: e.g. Menstruation (monthly) or hibernation (yearly).
All bodily rhythms are controlled by an interaction of what?
- Endogenous pacemakers (ep’s). Internal biological structures that control and regulate the rhythm.
- Exogenous zeitgebers (time givers) (ez’s). External environmental factors that influence the rhythm.
What are biological rhythms?
Cyclical changes in body activity.
What are circadian rhythms?
A type of biological rhythm in which a pattern of behaviour occurs or recurs approximately every 24 hours and which is set and reset by environmental light levels.
What are endogenous pacemakers?
Internal body clocks that regulate many of our biological rhythms.
What are exogenous zeitgebers?
External cues that may affect (or entrain or regulate) our biological rhythms.
Give an example of a circadian rhythm.
Sleep-wake cycle.
What are the main exogenous zeitgebers that determine when we sleep and wake up?
Light and darkness.
In what year did micheal siffre complete his cave study?
1962.
What did michael siffre want to investigate?
To investigate the power of the “free running” circadian rhythm so decided to enter a cave with no exogenous zeitgebers (external cues) to guide his rhythms.
What did he document down in the cave?
He documented his sleep wake cycle and found that it naturally settled at around 25 hours. When he emerged on the 17th september 1962, he believed it was the 20th august.
Describe and explain support study for the cave study?
Aschoff & Weaver (1976) sent participants in to a world war 2 bunker for four weeks. All but one participant displayed a circadian rhythm between 24 and 25 hours. This suggests that the natural “free running” sleep wake cycle is slightly longer than 24 hours, but it is governed by exogenous zeitgebers (day light, meal times etc.) Associated with our 24 hour day.
Describe and explain a conflicting evidence study for the cave study?
Simon Folkard et al. (1985) studied a group of 12 people who agreed to live in a dark cave for 3 weeks, retiring to bed when the clock said 11.45pm and rising when it said 7.45am. Over the course of the study, the researchers gradually speeded up the clock so the apparent 24 hours eventually lasted 22 hours. It was revealed that only one participant was able to adjust comfortably suggesting the existence of circadian rhythms that cannot easily be overridden by changes in the external environment.
Light enters the eyes where light-sensitive cells containing the ………. …………. Act as detectors and send messages about environmental light levels to the scn.
This information is then used to coordinate the activity of the ……… …… ………
This explains why we sleep when it is dark and are awake when it is light. It also works whilst we have our eyes closed.
Protein melanopsin, sleep-wake cycle.
What did decoursey et al (2000) find?
They destroyed the scn connections in the brains of 30 chipmunks who were then returned to their natural habitat and observed for 80 days. The sleep-wake cycle of the chipmunks 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).
What did Ralph et al (1990) find?
They bred ‘mutant’ hamsters with a 20-hour sleep-wake cycle. When scn cells from the foetal tissue of ‘mutant’ hamsters were transplanted into the brains of normal hamsters, the cycles of the second group defaulted to 20 hours.
What was Campbell and Murphy’s light pad study?
Campbell & Murphy’s (1998) findings suggest that light is such a powerful exogenous zeitgeber that it does not necessarily need to enter the eyes to affect the sleep wake cycle – it can affect our biological rhythm.
During their study, they woke the 15 participants at random intervals during the night to shine a light pad on the back of their knees.
The research managed to create a deviation of up to 3 hours in the participants’ sleep-wake cycle.
What did Damilola et al (2000) find?
Damilola et al. (2000) demonstrated how changing feeding patterns in mice could alter the circadian rhythm of cells in the liver by up to 12 hours, whilst leaving the rhythm of the scn unaffected. This suggests that there may be many other complex influences on the sleep/wake cycle, aside from scn.
give a limitation of Decourcy’s research.
A disturbing issue in relation to decoursey et al. Study is the ethics involved in such research. The animals were exposed to considerable harm, and subsequent risk, when they were returned to their natural habitat. Whether what we learn from investigations such as these justifies the aversive procedures involved is a matter of debate.
Describe and explain supporting evidence from miles (1977)
miles et al. (1977) recount the story of a young man, blind from birth, with a circadian rhythm of 24.9 hours. Despite exposure to social cues, his sleep/wake cycle could not be adjusted, and consequently, he had to take sedatives at night and stimulants in the morning to keep pace with the 24 hour world. Similarly, studies of individuals who live in artic regions show normal sleep patterns despite the prolonged exposure to light.
Why does the study by campbell and murphy limit reliability?
The findings from campbell and murphy study have yet to be replicated. Other psychologists have been critical of the manner in which the study was conducted and have suggested that there may have been some limited light exposure to the participants eyes – a major confounding variable. Also, isolating one exogenous zeitgeber in this way does not give us insight into the many other zeitgebers that influence the sleep/wake cycle, and the extent to which these may interact.
One strength of circadian rhythms is knowledge of circadian rhythms has given researchers a better understanding of the adverse consequences that can occur as a result of their disruption (desynchronisation). Explain this further and suggest what it means?
For instance, night workers engaged in shift work experience a period of reduced concentration around 6 in the morning (a circadian trough) meaning mistakes and accidents are more likely (bovin et al 1996). Research has also suggested a relationship between shift work and poor health: shift workers are three times more likely to develop heart disease (knutsson, 2003) which may in part due to the stress of adjusting to different sleep/wake patterns and the lack of poor-quality sleep during the day. Thus, research into the sleep/wake cycle may have economic implications in terms of how best to manage worker productivity.
Another strength of circadian rhythms is that the research has practical application. Describe and explain this.
Circadian rhythms co-ordinate a number of the body’s basic processes such as heart rate, digestion and hormone levels. This in turn has an effect on pharmacokinetics, that is, the action of drugs on the body and how well they are absorbed and distributed. Research into circadian rhythms has revealed that there are certain peak times during the day or night when drugs are likely to be at their most effective. This has led to the development of guidelines to do with the timing of drug dosing for a whole range of medications including anticancer, cardiovascular, respiratory, anti-ulcer and anti-epileptic drugs (baraldo, 2008).
A limitation is findings for circadian rhythms cannot be generalised. Explain why.
Studies of the sleep/wake cycle tend to involve small groups of participants, as in the experiment by aschoff and wever, or studies of single individuals, as in the case of siffre. The people involved may not be representative of the wider population and this limits the extent to which meaningful generalisations can be made. In his most recent cave experience in 1999, siffre observed, at the age of 60, that his internal clock ticked much more slowly than when he was a young man.
What did knutterson find? What year?
Found that night shift workers were more likely to experience stroke, heart disease and early death. 2003.
What did pressers find? What year?
Study of 3,500 married couples found that those where one spouse was working fixed night shifts had a three times higher divorce rate in the first 5 years of marriage than those working more sociable shift patterns. 2004.
Research into the effects of desynchronisation has a practical application in terms of improving worker productivity, reducing workplace risks, and ultimately benefiting the economy as a result. What did boivin et al (1996) find?
boivin et. Al (1996) note that concentration is at its lowest between 4-6am (the circadian trough) and there have been numerous incidents documented during this time, such as:
* The chernobyl disaster
* Three mile island nuclear reactor meltdown
* Bhopal chemical explosion
* Exxon valdez oil tanker spillage
Explain rotating vs fixed shift patterns.
Rotating patterns tend to involve a block of mornings, a block of afternoons and a block of nights, whereas a fixed shift pattern might be a permanent night shift.
These can be fast rotation - a week of each - or slow rotation - a month of each.
Shift patterns can be clockwise - starting with mornings and ending with nights - or anti-clockwise, which is the reverse.
Most research suggests that slow, clockwise rotations or fixed shifts promote the best synchronisation, productivity and overall physical and psychological health of workers.
What did czeisler find in 1982?
czeisler et al (1982) were called in to solve shift related problems at a chemical plant in utah, usa. After implementing both a slow, clockwise rotation and a fixed shift pattern (two separate groups) a number of benefits were reported. These included greater productivity, fewer accidents, increased morale and improvements to the health of workers.
However, monk & folkard (1983) reported that rapidly rotating shifts (i.e. Working 2 or 3 days on any one shift) were preferable to slower rotation of shifts. This seemingly contradicts the work of czeisler.
Even with a fixed shift pattern such as 10pm to 6am (night shift) there are issues. Although the worker will adapt to this pattern by experiencing a shift in biological rhythm there will be disruption at the weekend when presumably, not being at work, they will adopt a more sociable day pattern of recreation before restarting the night shift the following week.
What did Fuller (2006) find about reducing symptoms of jet lag?
Found that a period of fasting before travel followed by eating at times relevant to the new time zone was effective at altering biological rhythms.
What did Saper find in 2008?
Suggests that as well as the main ‘master’ clock in the scn there is also a ‘feeding clock’ which depends on food intake. In mice, this feeding clock was found to override the scn and kept them awake until food was found.
What did Klerman in 2009 find out about jet lag?
Found that taken just prior to bedtime in the new time zone, was effective in allowing sufferers of jet lag to get to sleep sooner than their body clock would normally allow.
What does ultradian mean?
“less than a day”, more than once in a 24 hour period, such as sleep stages.
What does infradian mean?
“greater than a day”, cycles that last for a week, month or year, such as the menstrual cycle and seasonal affective disorder (sad).
What is the follicle stimulating hormone (fsh)?
Causes the maturation of an egg in the ovary.
What is the luteinising hormone (lh)?
Stimulates the release of the egg.
What did mcclintock (1998) do?
Mcclintock et. Al (1998) demonstrated menstrual synchronicity in a 10 year longitudinal study of 29 women with irregular menstrual cycles.
Sweat from the women’s armpits was collected, frozen and sterilised, leaving behind pure pheromones.
These pheromones were then applied to the top lip of another woman in the group, and the effects were recorded. 68% of mcclintock’s participants experienced changes to their menstrual cycle.
what is SAD?
A depressive disorder with a seasonal pattern, sometimes called the ‘winter blues’ because sufferers tend to experience depression during the winter months
(september to february) when the number of daylight hours becomes shorter.
It is more common in those who live a long way from the equator.
What is phototherapy and what is it used for?
One of the most effective treatments for sad is phototherapy. This involves a lightbox that simulates very strong light in the morning and evening. It is thought to reset melatonin levels in people with sad. Phototherapy relieves symptoms in up to 60% of sufferers (eastman et al, 1998).
Explain stage 1 and 2 of the sleep wake cycle.
Light sleep where the person may be easily woken. At the beginning of sleep, brainwave patterns start to become slower and more rhythmic (alpha waves), becoming even slower as asleep becomes deeper (theta waves).
Explain stage 3 and 4 of the sleep wake cycle.
Involves delta waves which are slower still and have a greater amplitude than earlier wave patterns. This is deep sleep or slow wave sleep and is difficult to rouse someone at this point.
Explain stage 5 of the sleep wake cycle.
REM sleep where the body is paralysed yet brain activity speeds up significantly in a manner that resembles the awake brain. Rapid eye movement to denote the fast, jerky activity of the eyes under the eyelids.
What did dement and Kleitman (1957) do?
Dement & Kleitman monitored the sleep patterns of 9 adult participants in a sleep lab. Brainwave activity was recorded on an eeg and the researchers controlled for the effects of caffeine and alcohol. Rem activity during sleep was highly correlated with the experience of dreaming, and participants woken during dreaming reported very accurate recall of their dreams.
What is the basic rest activity cycle (brac)?
much evidence from eeg recordings suggests the existence of a 90-minute cycle during sleep. However, kleitman (1969) also suggested that a similar 90-minute rhythm cycle continues during waking hours. He called this the basic rest-activity cycle (brac) which is characterised by a period of alertness followed by a spell of physiological fatigue. This occurs across a 90-minute cycle which then recurs during the course of the day.
Anecdotal evidence supports the existence of brac such as the frequent observation that students find it difficult to concentrate for periods longer than 90 minutes at a time. Similarly, most people will require a (coffee) break in order to divide up their working morning and also their afternoon.
In a widely cited study of prodigious violinists, ericsson et al. (1993) found that the best performers tended to practise for three sessions during the course of the day, each session lasted no more than 90 minutes, and there was a break between each in order to ‘recharge’.
We can therefore use the brac as another example of an ultradian rhythm.
It is said there is casts doubt on the chemical infuence of phototherapy. Explain this and provide detail.
one of the most effective treatments for sad is phototherapy. This involves a lightbox that simulates very strong light in the morning and evening. It is thought to reset melatonin levels in people with sad. Phototherapy relieves symptoms in up to 60% of sufferers (eastman et al, 1998). However, the same study recorded a placebo effect of 30% using a ‘sham negative ion generator’ (participants were told it was another form of treatment).
What study suggests that rem sleep is an important component of the ultradian sleep cycle. What study did this and provide detail.what study suggests that rem sleep is an important component of the ultradian sleep cycle. What study did this and provide detail.
A landmark study by dement and kleitman (1957) monitored the sleep patterns of nine adult participants in a sleep lab. Brainwave activity was recorded on an eeg and the researchers controlled for the effects of caffeine and alcohol. Rem activity during sleep was highly correlated with the experience of dreaming were, and participants woke during dreaming reported very accurate recall of their dreams. Replications of their investigation have noted similar findings, though the small size of the original study has been criticised by some.
