biopsychology

Question 1

what is the nervous system made up of?

Answer 1

brain and spinal cord

Question 2

what is the peripheral nervous system made up of?

Answer 2

relays messages from the environment to the CNS, via sensory neurones, and from the CNS to effectors, via motor neurones.

Question 3

what is the peripheral nervous system further subdivided into?

Answer 3

the autonomic nervous system and the somatic nervous system

Question 4

what does the autonomic nervous system do?

Answer 4

it controls involuntary, vital functions of the body such as maintaining heart and breathing rates.

Question 5

what does the somatic nervous system do?

Answer 5

it receives information from sensory receptors belonging to each of the 5 senses and results in effectors being stimulated in the CNS via: motor neurones

Question 6

what is the autonomic system divided into and how do they work together?

Answer 6

the sympathetic and parasympathetic
these branches work as an antagonistic pair

Question 7

sympathetic nervous systems job

Answer 7

increased heart and breathing rate.
causes vasodilation and pupil constriction

Question 8

endocrines systems job

Answer 8

it sends chemical messages around the body
its where hormones are secreted into the blood stream and then are transported towards target cells in the blood, with complementary receptors.

Question 9

why is the pituitary gland considered?

Answer 9

the ‘master gland’ because it controls the release of hormones from all other glands in the body.

Question 10

what does the adrenal gland release?

Answer 10

adrenaline (fight or flight)

Question 11

what is the fight or flight response

Answer 11

1.The body senses and becomes aware of a stressor in the environment e.g. the sound of a speeding car.
2.Through sensory receptors and sensory neurones in the PNS, this information is sent to the hypothalamus in the brain which coordinates a response and triggers increased levels of activity in the sympathetic branch of the ANS.
3.Adrenaline is released from the adrenal medulla in the adrenal glands, and is transported to target effectors, via the blood and through the
action of the endocrine system.

Question 12

what is synaptic transmission?

Answer 12

is a method of neurons communicating with each other, relaying information to the CNS across sensory neurons and carrying out responses dictated by the brain through sending information to effectors via motor neurons.

Question 13

describe the process of synaptic transmission:

Answer 13

1. An action potential arrives at the presynaptic membrane, causing depolarisation through the opening of voltage-dependent calcium ion channels, and the consequent influx of calcium ions.
   2.The increased concentration of calcium ions within the membrane causes the vesicles, containing
   neurotransmitter, to fuse with the presynaptic membrane and release their contents into the synaptic cleft through exocytosis.
2. The neurotransmitter diffuses across the synaptic cleft, down a concentration gradient, and binds to complementary receptors on the post-synaptic membrane. This can result in an inhibitory or excitatory effect in the postsynaptic membrane.
3. The resultant action potential will then be transmitted along the axon of the following neuron, resulting in a ‘cascade’ of neurotransmission!

Question 14

what’s the difference between inhibitory and excitatory transmitters?

Answer 14

-Neurotransmitters can either have an inhibitory or excitatory effect. Inhibitory neurotransmitters (e.g. serotonin) reduce the potential difference across the postsynaptic membrane through the closure of the voltage-dependent sodium ion channels, reducing the likelihood that an action potential will be generated.

• Excitatory neurotransmitters (e.g. dopamine) increase the potential difference across the postsynaptic membrane through triggering the opening of more voltage-dependent sodium ion channels, increasing the likelihood that an action potential will be generated.

Question 15

what is localisation of the brain?

Answer 15

localisation of the brain suggests that specific areas are responsible for certain processes

Question 16

what are the different localised areas?

Answer 16

motor area
auditory area
visual area
somatosensory area

Question 17

describe the Motor area

Answer 17

-found in frontal lobe
-this area is involved in regulating and coordinating movements.
-Lesions or damage in the motor area result in an inability to control voluntary fine motor movements.

Question 18

describe the auditory area

Answer 18

-located on the superior temporal gyrus
-is responsible for processing auditory information and speech.
-Lesions or damage in the auditory area causes hearing loss,
-damage to specific parts of the auditory area (Wernicke’s area) results in Wernicke’s aphasia.

Question 19

describe the visual area

Answer 19

An area in the occipital lobe which is responsible for processing visual information.

Question 20

describe the somatosensory area

Answer 20

-An area of the parietal lobe
-it processes information associated with
the senses e.g. touch, heat, pressure etc. 1“These regions receive neuronal input from specific nuclei of the thalamus that correspond with the handling of sensation along the lines of touch, pain, temperature and limb position”.
-Lesions in this area result in a loss of ability to denote sensitivity to particular bodily areas.

Question 21

describe wernickes area

Answer 21

-Responsible for speech comprehension and located in the temporal lobe (the left temporal lobe for most people).
-Lesions or damage (e.g. through stroke and trauma) results in Wernicke’s aphasia, which is characterised by the use of nonsensical words (called syllogisms), no awareness of using incorrect words, but no issues with pronounciation and intonation.

Question 22

describe brocas area

Answer 22

-Responsible for speech production
-Located in the frontal lobe, usually in the left hemisphere.
-Lesions or damage results in Broca’s aphasia, characterised by difficulty forming complete sentences and understanding sentences, as well as failing to understand the order of words in a sentence and who they are directed towards i.e. I, you, we, him, me etc.

Question 23

support for localisation of brain function

Answer 23

+ Supporting evidence for localisation of brain function = Tulving et al demonstrated, using PET scans, that semantic memories were recalled from the left prefrontal cortex, whilst episodic memories were recalled from the right prefrontal cortex. This shows that different areas of the brain are responsible for different functions, as predicted by localisation theory. This idea was further supported by Petersen et al (1988) , who found that Wernicke’s area activation is required for listening tasks, whereas Broca’s area is required for reading tasks. This confirms the idea that Wernicke’s area is involved in speech comprehension, whilst Broca’s area is responsible for speech production.

+ Supporting Case Studies = Phineas Gage was injured by a blasting rod which intersected the left side of his face, tearing through his prefrontal cortex. 2“The damage involved both left and right prefrontal cortices in a pattern that, as confirmed by Gage’s modern counterparts, causes a defect in rational decision making and the processing of emotion”. Such case studies, particularly those showing marked differences after trauma, demonstrate the idea that some areas of the brain are responsible for specific functions. However, with the use of case studies, the subjectivity of the conclusions drawn and the unusual sample, alongside a lack of control over confounding and extraneous variables, must also be considered.

+ Supporting evidence for localisation of brain function = Tulving et al demonstrated, using PET scans, that semantic memories were recalled from the left prefrontal cortex, whilst episodic memories were recalled from the right prefrontal cortex. This shows that different areas of the brain are responsible for different functions, as predicted by localisation theory. This idea was further supported by Petersen et al (1988) , who found that Wernicke’s area activation is required for listening tasks, whereas Broca’s area is required for reading tasks. This confirms the idea that Wernicke’s area is involved in speech comprehension, whilst Broca’s area is responsible for speech production.

+ Supporting Case Studies = Phineas Gage was injured by a blasting rod which intersected the left side of his face, tearing through his prefrontal cortex. 2“The damage involved both left and right prefrontal cortices in a pattern that, as confirmed by Gage’s modern counterparts, causes a defect in rational decision making and the processing of emotion”. Such case studies, particularly those showing marked differences after trauma, demonstrate the idea that some areas of the brain are responsible for specific functions. However, with the use of case studies, the subjectivity of the conclusions drawn and the unusual sample, alongside a lack of control over confounding and extraneous variables, must also be considered.

Question 24

weakness to localisation of brain function

Answer 24

— Contradictory Theory = The opposite to localisation theory would be a holistic view of brain function, suggesting that each function requires several brain areas to be activated and that these functions are not restricted to these areas. For example, after removing 20-50% of the cortices belonging to rats, found that no specific brain area or lesion was associated with learning how to traverse through a maze. This suggests that intelligence, or even learning, is too complex and advanced a cognitive ability to be restricted to certain areas of the brain. Therefore, this suggests that localisation theory may provide a better explanation for ‘simple’, rather than complex, brain functions.

Question 25

what is plasticity?

Answer 25

Refers to the brain’s ability to physically and functionally adapt and change in response trauma, new experiences and learning. Neuroplasticity was demonstrated by Maguire et al (2006).

Question 26

what did Gopnik et al’s theory state that came before plasticity?

Answer 26

there is a ‘critical window’ for synaptic and neuronal connection formation, which occurs during the first 3 years of life, after which no new neuronal connections would be formed (Gopnik et al).

Question 27

what is synaptic pruning?

Answer 27

the process by which extra neurons and synaptic connections are eliminated in order to increase the efficiency of neuronal transmissions

Question 28

what did Maguire et al find?

Answer 28

found a larger grey matter volume in the mid-posterior hippocampi of taxi drivers brains, alongside a positive correlation between an increasing grey matter volume and the longer the individuals had been taxi drivers. This may be because the hippocampus is associated with spatial awareness; an ability which taxi drivers must have when they complete The Knowledge test

Question 29

what is functional recovery?

Answer 29

its the ability of the brain to transfer the functions of areas damaged through trauma, to other healthy parts of the brain, thus allowing for normal functioning to carry on

Question 30

how is functional recovery enabled?

Answer 30

through the law of equipotentiality , axonal sprouting , reformation of blood vessels and recruiting homologous areas on the opposite side of the brain.

Question 31

what is ramachandrans research into functional recovery?

Answer 31

Ramachandran’s research into phantom limb syndrome demonstrates negative plasticity, because the neuroplasticity results in painful or negative consequences.

Question 32

what is Jodi millers case into functional recovery?

Answer 32

Whose entire right hemisphere was removed in an attempt to control her epileptic seizures. However, through the mechanisms of neuroplasticity, she was still able to control the right side of her body through the use of cerebral spinal fluid. This demonstrates positive plasticity, because the neuroplasticity results in desirable or positive consequences.

Question 33

advantages of functional recovery and plasticity?

Answer 33

+ Evidence supporting the positive and negative effects of neuroplasticity = Much research has been carried out into the phenomenon of plasticity. For example, Ramachandran et al. has demonstrated negative plasticity through providing an explanation for phantom limb syndrome in terms of cortical reorganization in the cortex and thalamus (particularly, the somatosensory area). Positive plasticity has been demonstrated by the case study of Jodi Miller, who has shown the power of recruiting homologous areas on the opposite side of the brain, axonal sprouting and the reformation of blood vessels. Therefore, there is evidence supporting not only the existence of, but also the uses of plasticity.

+ Neuroplasticity occurs in animals too = Hubel and Weisel (1970) sutured the right eye of kittens, who are blind from birth, for a period of 6 months, opening the eyes and several points and monitoring brain activity in the visual cortex. The researchers found that, although the right eye was closed, there was still activity in the left visual cortex, corresponding to the development of occular dominance columns. This was demonstrated by how 7“during the period of high susceptibility in the fourth and fifth weeks eye closure for as little as 3-4 days leads to a sharp decline in the number of cells that can be driven from both eyes”. This therefore supports the idea that areas of the brain receiving no input can take over the function of highly stimulated areas, despite originally having different functions.

+ Cognitive reserve may increase the rate of functional recovery = Cognitive reserve is the level of education a person has attained and how long they have been in education. Research suggests that an increased cognitive reserve increases the likelihood of making a disability-free recovery (DFR) after trauma, due to increased rates of neuroplasticity. For example, Schneider et al (2014) found that of the 8769 patients studied, 214 achieved DFR after 1 year. Of those, 50.7% had between 12 and 15 years of previous education and 25.2% had more than 16 years. This suggests that individuals who have been in education for a longer time may have developed the ability to form neuronal connections at a high rate, and therefore experience high levels of functional recovery, demonstrating positive plasticity.

Question 34

disadvantages of functional recovery and plasticity?

Answer 34

— There are limits to spontaneous and functional recovery = Although after trauma the brain activates secondary neural circuits which contribute towards reinstating normal function (law of equipotentiality), the brain can only ‘repair’ itself up to a specific point, after which motor therapy or electrical stimulation is needed to increase recovery rates. For example, Lieperta et al (1998) found that after constraint-induced movement therapy, the motor performance of stroke patients improved significantly. Therefore, this suggests that functional recovery cannot be relied upon to reinstate normal function.

Question 35

what is hemispheric lateralisation?

Answer 35

Hemispheric lateralisation = The idea that each hemisphere (half) of the brain is mainly responsible for certain behaviours, processes and activities.

Question 36

what is the holistic view of brain function?

Answer 36

the holistic theory of brain function suggests that function is distributed across the whole brain (i.e. is global).

Question 37

how does each hemisphere control the body?

Answer 37

The right hemisphere controls the left side of the body, and vice versa. Therefore, information which we receive from the left visual field is processed by the right hemisphere, which then coordinates a response to affect the left side of the body.

Question 38

what was Sperry et al research?

Answer 38

Conducted split-brain research on 11 epileptic patients. In order to control their seizures, these patients underwent surgical lesioning of the corpus callosum, through a procedure called a cerebral commissurotomy, where information processed by one hemisphere cannot be relayed to the other hemisphere. Therefore, it is possible to expose a single hemisphere to certain stimuli in split-brain patients, and thus infer the functions of each hemisphere.

Question 39

how was Sperrys et Al, research carried out?

Answer 39

The patients had one of their eyes covered, so that information would not be received by both eyes. The stimuli was flashed onto a screen for one-tenth of a second. This prevented both visual fields of the eye being exposed to the information, so only one hemisphere would process it. Therefore, their research was conducted under strictly controlled conditions, through the use of a laboratory experiment.

Question 40

for the section of the experiment called “describing what you see” what were the results?

Answer 40

If the stimulus word was exposed to the right visual field, then it would be processed by the left hemisphere and the patient would say the word.

This is because the left hemisphere contains the ‘language centres’ of the brain and so allows for speech.

However, if the same stimulus word was exposed to the left visual field, then it would be processed by the right hemisphere and the patient would write the word using their left hand.

This is because the right hemisphere contains the visuo-spatial centres of the brain, allowing for the physical act of writing.

The patient would not be able to give a verbal description of the word, because the right hemisphere contains no language centres.

Question 41

For the section of the experiment called “matching words or faces” what were the results?

Answer 41

The right hemisphere appeared to dominate the ability to match a list of faces to a given stimulus.

This is due to the right hemisphere containing the brain’s visuo-spatial centres, thus allowing for the visual identification and processing of the faces.

Question 42

For the section of the experiment called “Words presented simultaneously “ what were the results?

Answer 42

If two words were presented at the same time, each to one of the visual fields, the patient would say the word presented to the right visual field (processed by the left hemisphere with language centres) and write down the word presented to the left visual field (processed by the right hemisphere and containing visuo-spatial centres).

Question 43

disadvantages of split brain research into hemispheric lateralisation?

Answer 43

— Lack of control with the sample selection = The epileptic patients had been taking anti-epilepsy medications for extended and different periods of time, which may have affected their ability to recognise objects and match words, due to causing cerebral neuronal changes. Secondly, although all patients had undergone a commissurotomy, there may have been differences in the exact procedures e.g. differing extent of the lesioning of the corpus callosum. This would have affected the degree to which the two hemispheres could relay information between themselves. Therefore, these two confounding variables had not been controlled, meaning that the lateralised functions may be examples of unreliable causal conclusions.

— The differences in function may not be so clear-cut = With evidence making the drastic distinctions that the left hemisphere is responsible for language (analyser) whilst the right is responsible for visual- spatial tasks (synthesiser), this has given the public the false impression that the two hemispheres are ‘opposite’ in function and that they can receive such labels. However, as suggested by Pucetti (1980), there have been cases of split-brain patients who are left-handed but produce and comprehend speech in the right hemisphere, which opposes the predictions made by lateralisation theory. Therefore, it is important not to jump to conclusions and to appreciate that, through recruitment of homologous areas on the opposite side of the brain, each hemisphere is not restricted to specific functions.

Question 43

For the section of the experiment called “Recognizing objects placed into the hands “ what were the results?

Answer 43

If an object was placed into the patient’s right hand, they would be unable to identify that it is there, because the information would be processed by the left hemisphere which only has language centres, and no visuo-spatial centres.

Therefore, if an object was placed into the patient’s left hand, they would be able to identify the object and choose a similar one from a hidden bag, due to the action of the visuo-spatial centres.

Question 44

advantages of split brain research into hemispheric lateralisation?

Answer 44

+ Clearly demonstrated lateralisation of function = Split-brain research was pivotal in establishing the differences in functions between the two hemispheres, and so opposing the holistic theory of brain function. The left hemisphere was demonstrated as being dominant for language tasks, due to containing language centres, whereas the right hemisphere was demonstrated as being dominant for visuo-spatial tasks. Therefore, this suggests that the left hemisphere is the analyser, whereas the right hemisphere is the synthesiser, and so there are marked differences between the two.

+ Contribution to discussions about lateralisation theories = Such evidence strongly supported the idea of a ‘dual mind’ where the two hemispheres represent two sides of the mind. Pucetti (1980) critisised Sperry and Gazaniga’s work by pointing out that 9“visual stimuli impinging on the left half of each eye’s retina do not go to the right, but to the left cerebral hemisphere (and vice versa), since the retina is concave and each half retina receives light from the contralateral side of the body”. Therefore, it is clear that split-brain research has sparked much debate about the physiological and theoretical basis of brain function and human abilities.

Question 45

what is EEG (way of investigating the brain)?

Answer 45

To study how the brain reacts to specific events, researchers analyze EEG data by averaging it across multiple trials.

This process filters out unrelated brain activity, leaving only the brainwaves directly triggered by the event, known as event-related potentials (ERPs).

These ERPs show the brain’s specific responses to sensory, motor, or cognitive events.

Question 46

Advantages of EEG?

Answer 46

+ Excellent Temporal Resolution-Neural processes are measured more specifically than in an EEG.

+Widely used in the measurement of cognitive deficits and functions.

Question 47

Disadvantages of EEG

Answer 47

-Lack of standardisation in ERP methodology in different research studies.

-Background noise and extraneous material can be an obstacle.

Question 48

what is fMRI’s scans (ways of investigating the brain)?

Answer 48

These rely on the haemodynamic response. Areas of the brain with high levels of activity have a larger requirement for oxygenated blood, leading to a higher rate of blood deoxygenation.

As measured through the bold response, the deoxyhaemoglobin in the blood in these highly active areas absorbs the signal produced by the scan, so such areas appear brightly coloured on the scan.

Question 49

advantages of fMRI scans

Answer 49

+ High spatial resolution as up to 4 images can be produced per second.
+ Can be used whilst a patient is carrying out a task, and so data from fMRI scans can help us to make inferences about brain function and localisation.
+ Does not use ionising radiation, unlike PET scans, and so is safer.

Question 50

disadvantages of fMRI scans

Answer 50

— Poor temporal resolution because there is approximately a 5 second difference between neuronal activity and the produced image.

Question 51

what are EEG scans?

Answer 51

Through the use of electrodes attached to the scalp, EEG scans measures and amplifies the electric activity across the whole brain i.e. action potentials being transmitted across the axons of neurons.

Question 52

advantages of EEG scans?

Answer 52

+ Particularly useful in investigating the characteristics of the different stages of sleep, as
demonstrated by Dement and Kleitman.
+ Much higher temporal resolution than fMRI scans, and so more appropriate for the monitoring of
ongoing cerebral states and activity.
+ Useful in the diagnosis of epilepsy, which is characterised by random bursts of activity.

Question 53

disadvantages of EEG scans?

Answer 53

— Lower spatial resolution compared to fMRI scans, with particular difficulty in differentiating activity between adjacent areas.

Question 54

what are post-mortem examinations?

Answer 54

These involve a comparison of the patient’s brain with that of a healthy, neurotypical brain. Any differences (e.g. lesions, damage, abnormally large or small areas) are assumed to have caused the neruological problem the patient faced in their lifetime.

Question 55

disadvantages of post-mortem examinations

Answer 55

— Incorrectly makes the assumption that differences compared with the neurotypical brain must be the explanation for neurological or cognitive deficits. Prolonged drug use, stress and genetic factors may be other plausible explanations.
— Ethical issues arise because informed consent cannot always be obtained before the patient dies or from the family. The patient may be unable to give informed consent e.g. HM suffered from deficits in his short-term memory, and so would not remember having signed the document.

Question 56

advantage of post mortem examination

Answer 56

+ Particularly useful for advancing medical knowledge, and being the basis of further research into
certain areas of the brain e.g. Broca used a post-mortem examination on his patient Tan, which led to the identification of Broca’s area and was the foundation of further research into the theory of the localisation of brain function.

Question 57

what are biological rhythms?

Answer 57

Periodic biological fluctuations in an organism that corresponds to, and is in response to, periodic environmental change

Question 58

what does endogenous mean

Answer 58

endogenous= your biological rhythms are controlled by internal clocks e.g. the suprachiasmatic gyrus

Question 59

what does exogenous mean

Answer 59

exogenous= your biological rhythms are controlled by external, environmental factors e.g. exposure to sunlight

Question 60

what are the three types of biological rhythms?

Answer 60

circadian, infradian and ultradian.

Question 61

what are Exogenous zeitgebers?

Answer 61

External changes in the environment which affect or ‘entrain’ our biological rhythms.

Question 62

what are circadian rhythms?

Answer 62

A type of biological rhythm which completes one full cycle every 24 hours e.g. the sleep-wake cycle. Like other biological rhythms, it is affected by both endogenous pacemakers and exogenous zeitgebers.

Question 63

Who studied sleep-wake cycle?

Answer 63

Siffre

Question 64

describe siffre’s study

Answer 64

he descended into a cave on July 16th 1962, completely devoid of natural light. He finished his experiment on September 14th, believing it to be August 20th! This demonstrates that prolonged exposure to a strong exogenous zeitgeber such as light, the sleep-wake cycle becomes disrupted and there is a disconnection between psychological time and the clock. His sleep-wake cycle did not conform to a cyclical 24 hour-period, but was around 24 hours and 30 minutes, with Siffre himself determining when to sleep and when to eat. Therefore, this demonstrates that 11 “there was an internal clock independent of the natural terrestrial day/night cycle”. This describes a ‘free-running’ circadian rhythm i.e. one which is not affected by exogenous zeitgebers.

Question 65

what was Aschoff and Wever’s study?

Answer 65

55 participants were deprived of natural light whilst spending 4 weeks in an underground bunker. The researchers found that “all subjects showed free-running circadian rhythms, with the average periods of wakefulness and sleep ranging from 23.9 to 50.0 hours. 36 subjects remained internally synchronized during the whole experiment”.

Question 66

what did there study show?

Answer 66

it demonstrated that although the free-running circadian rhythm is more than 24 hours long, as a society we have specific exogenous zeitgebers which entrain the rhythm to conform to a 24 hour cycle.

Question 67

disadvantages of studies into sleep-wake cycle:

Answer 67

— Individual differences in circadian rhythms = Circadian rhythms may not and do not always have to conform to cyclical 24 hour periods. For example, Dr. Espie, a Professor of sleep medicine at Oxford University, delayed the starting time of Monkseaton High School to 10 AM, instead of the usual 8AM. The researchers noted that 13“GCSE results went up from 34% of pupils scoring 5 A-C grades including English and Maths, to 53%. For disadvantaged students, the rates of scoring 5 A-C grades increased from 12% to 42%”. Therefore, this is a real-life example of how the circadian rhythms of teenagers specifically are not always in line with that of adults, and so an appreciate of this can improve educational attainment.

— The confounding effect of artificial light = As demonstrated by Czeisler et al (1999), artificial lighting can create shifts in circadian rhythms by up to 6 hours. Siffre’s research was conducted at a time where researchers believed that artificial lighting had no effect on biological rhythms. The use of artificial light meant that over 2 months, Siffre could have entrained his own circadian rhythm through signaling sleeping and waking times by using the light, meaning that the conclusions made about his ‘free-running’ circadian rhythm may not be entirely accurate.

— Detrimental impacts on health in shift workers = 14Karlsson, Knutsson and Lindahl (2001) found that shift work was associated with obesity, high triglycerides and low concentrations of HDL cholesterol, which the researchers suggest may demonstrate a link between the desynchronisation of circadian sleep-wake cycles in shift workers and the consequent disruptions in the biological control of metabolism (and therefore core body temperature). This suggests that there may be practical uses in an improved understanding of the effects of desynchronisation. This in turn has economical implications, in terms of companies who employ shift-workers making the effort to revise their policies in order to reduce days taken off sick.

— Use of case studies and small samples in isolation investigations = Although Siffre conducted multiple isolation studies, his results may not be able to be generalised to the wider population, especially as individual differences in the duration and stages of circadian rhythms has been shown (i.e. Monkseaton High School), hence his results may lack ecological validity. For example, even Siffre himself noted that as he grew older, his endogenous pacemaker ticked at a slower rate, which may have acted as an uncontrolled confounding variable in his investigations. The same can be said for other isolation studies, such as Aschoff and Wever, where large numbers of participants are unlikely to want to participate. This again limits the extent to which the findings represent the experiences of the general population.

Question 68

what is the infradian rhythm?

Answer 68

lasts longer than 24 hours and can be weekly, monthly or annually. A monthly infradian rhythm is the female menstrual cycle, which is regulated by hormones that either promote ovulation or stimulate the uterus for fertilisation

Question 69

what did McClintock study?

Answer 69

demonstrated menstrual cycle synchronisation amongst 29 women who all had irregular periods. The pheromones from 9 of the women were collected through the use of a pad under the armpit, and then rubbed onto the upper lip of the remaining 20 women, corresponding to the specific days of their cycle. The researchers found that “recipients had shorter cycles when receiving axillary compounds producing by donors in the follicular phase of the menstrual cycle (+ 1.7 +/- 0.9 days) and longer cycles when receiving ovulatory compounds (+ 1.4 +/— 0.5 days).

Question 70

What is S.A.D?

Answer 70

seasonal affective disorder

Question 71

what is SAD caused by?

Answer 71

it is caused by disruption to the sleep-wake cycle, and commonly occurs in the winter. Longer nights means that more melatonin is secreted from the pituitary gland, via the endocrine system, which changes the production of melatonin, leading to feelings of loneliness and depression.

Question 72

what is the ultradian rhythm?

Answer 72

Ultradian rhythms are biological rhythms that occur over a period shorter than 24 hours. Examples of ultradian rhythms include the sleep cycle, the feeding cycle, and the hormonal cycles that regulate digestion and metabolism.

Question 73

what did dement and kleitman find in their stages of sleep study?

Answer 73

Dement and Kleitman (1957) studied 33 adults, where their caffeine and alcohol intake had been controlled, in order to remove the effect of these extraneous variables and increase the reliability of the findings. Using EEG scans, the researchers found that 15“discrete periods of rapid eye movement potentials were recorded without exception during each of 126 nights of undisturbed sleep”. Since participants were able to accurately recall their dreams when awoken during REM sleep, the assumption was made that dreaming is associated with REM sleep. Therefore, there is clear evidence supporting the idea of a distinct set of sleep stages.

Question 74

disadvantages of biological rhythms

Answer 74

— Menstrual synchronisation is not always present in all-female samples = For example, Trevathan et al (1993) noted that he had found no evidence of menstrual synchronisation in the all-female participants used, which suggests that there are external (extraneous) variables which may affect the timing and duration of their menstrual cycles. McClintock et al. did not control for such extraneous factors e.g. smoking, physical activity and alcohol consumption. Therefore, this raises doubts about the strength of the influence of pheromones, as an exogenous zeitgeber which can entrain infradian rhythms.

— Dispute over the chemical and hormonal basis of SAD = Gloth et al (1999) found that, when treating sufferers of SAD with either Vitamin D supplements or broad-spectrum phototherapy, “all subjects receiving vitamin D improved in all outcome measures. The phototherapy group showed no significant change in depression scale measures”. Patients who’d been given vitamin D supplements also experienced a 74% improvement in their depression measures. Therefore, this suggests that phototherapy is ineffective in treating SAD. Since phototherapy involves exposure to bright light in order to increase the rate at which the pineal gland secretes melatonin, this implies that melatonin and serotonin levels have little parts to play in the development of SAD and in the entrainment of circadian sleep-wake cycles.

Question 75

advantages of biological rhythms

Answer 75

+ Animal studies supporting the role of pheromones = The link between the pheromone release and animal behaviour has been extensively supported. For example, Luo et al (2003) studied the effects of pheromonal signals in the olfactory bulb of mice and concluded that 16“mammals encode social and reproductive information by integrating vomeronasal sensory activity specific to sex and genetic makeup”. Therefore, this suggests that endogenous pacemakers have a critical role in the entraining of biological rhythms in animals, whose findings can then be generalised to humans.

Question 76

what are endogenous pacemakers?

Answer 76

Internal bodily regulators of biological rhythms, affecting or ‘entraining’ such biological rhythms to conform to certain cyclical periods e.g. one cycle every 24 hours for circadian rhythms.c

Question 77

How does the suprachiasmatic nucleus (SCN) regulate sleep and wakefulness through melatonin and serotonin?

Answer 77

The suprachiasmatic nucleus (SCN) receives light and day-length information from the eyes, which is processed by the brain’s visual area and passed to the SCN. The SCN then uses this information to control melatonin release from the pineal gland. At night, with low light exposure, the SCN increases melatonin release, lowering serotonin and causing sleepiness. During the day, high light exposure causes the SCN to reduce melatonin, allowing serotonin levels to rise and promoting wakefulness.

Question 78

who investigated the effect of the SCN?

Answer 78

DeCoursey et al (2000), surgically lesioned the SCNs of 30 chipmunks, and compared their circadian rhythms in their natural habitat with 17 controls. The researchers found that the vast majority of the experimental group had been killed within the first 80 days after being returned to their habitat and episodes of nocturnal movement were detected within the permanent dens by radio telemetric data logging, especially in supra- schismatic nucleus-lesioned animals

Question 79

what did Ralph et al do on scn cells?

Answer 79

he extracted SCN cells from hamsters which showed abnormal sleep-wake cycles, and inserted these cells into healthy hamster foetuses. The researchers found that the restored rhythms always exhibited the period of the donor genotype, regardless of the direction of the transplant or genotype of the host. The basic period of the overt circadian rhythm therefore is determined by cells of the suprachiasmatic region

Question 80

what are exogenous zeitgeibers?

Answer 80

External environmental changes, affecting or ‘entraining’ biological rhythms to conform to certain cyclical time periods.

Question 81

what is an example of an exogenous zeitgeiber?

Answer 81

Social cues, like set meal and bedtimes, are external signals that help sync our biological rhythms. To avoid jet lag, it’s helpful to adjust to the sleeping and eating schedule of your destination to keep your circadian rhythm in sync.

Question 82

disadvantages of exogenous and endogenous zgeitgeibers

Answer 82

— The influence of the SCN may be overestimated. For example, Damiola et al. demonstrated that the circadian rhythm of mice liver cells could be influenced to experience a 12 hour discrepancy, leaving the SCN unaffected. These so-called ‘peripheral oscillators’, also present in the adrenal gland and lungs, are collections or systems of cells which act independently of the SCN, each having their own biological rhythm. Therefore, the SCN is not so important as once thought.

— There are considerable ethical issues with the use of animals in such research, particularly if they are deliberately put in harms way as was the case with Decoursey et al, thus breaching the BPS ethical guideline of protection from psychological and physical harm. Although this does not impact upon the utility or validity of the findings, a cost-benefit analyses would have to be conducted to assess whether such ethical costs outweigh the benefits of an improved understanding of exogenous zeitgebers and endogenous pacemakers. A second problem occurs with the limitations of generalising findings from animal studies to humans, particularly due to differences in physiology and the number/types of circadian rhythms, thus limiting the ecological validity of such findings.

— There have also been recorded cases where exogenous zeitgebers and endogenous pacemakers have failed to entrain or alter circadian rhythms, as demonstrated by Miles et al (1977) who reported the case of a man with a sleep-wake cycle of 24.9 hours, which could not be changed through the use of either stimulants or sedatives. Therefore, this suggests that the influence of exogenous and endogenous factors may be overestimated!