Biopsychology Flashcards

Question

Synaptic Transmission

Answer 1

- Neurons transmit electrical impulses (known as action potentials) between the pre-synaptic neuron + the post-synaptic neuron - Synaptic transmission takes only a fraction of a second with the effects terminated by a process called re-uptake - The neurotransmitter is taken back by the vesicles on the pre-synaptic neuron where they are stored for later release - The quicker the neurotransmitter is taken back the shorter the effects

Answer 2

The neuron transferring the action potential

Answer 3

The neuron receiving the action potential

Answer 4

- When the action potential reaches the pre-synaptic terminal it triggers the release of neurotransmitters (chemical messengers) from sacs on the pre-synaptic membrane known as vesicles in a process called exocytosis - The released neurotransmitter will diffuse across the synaptic cleft (physical gap between the pre-synaptic membrane + post-synaptic membrane) where it binds to specialised post-synaptic receptor sites

Answer 5

- Neurotransmitters can be excitatory or inhibitory - Most can be both but GABA is purely inhibitory - Excitatory neurotransmitters causes an electrical charge in the membrane of the post-synaptic neuron resulting in an **excitatory post synaptic potential** (EPSP), meaning that the post-synaptic neuron is **more likely** to fire an impulse

Answer 6

Inhibitory neurotransmitters cause an **inhibitory post synaptic potential** (IPSP), making it **less likely** that the neuron will fire an impulse

Answer 7

- A neuron can receive both EPSPs + IPSPs at the same time - The likelihood that the neuron will fire an impulse is determined by adding up the excitatory + the inhibitory synaptic input - The net result of this calculation known as summation determines whether or not the neuron will fire an impulse - If the net effect is inhibitory the neuron will not fire + if the net effect is excitatory, the neuron will fire

Answer 8

- Info can only travel in ONE direction at a synapse - The **vesicles** containing neurotransmitters are ONLY present on the pre-synaptic membrane - The **receptors** for the neurotransmitters are ONLY present on the post-synaptic membrane - It is the binding of the neurotransmitter to the receptor which enables the info to be transmitted to the next neuron - Diffusion of the neurotransmitters mean they can only go from high to low concentration so they can only travel from the pre synaptic membrane to the post synaptic membrane

Answer 9

- Psychoactive drugs (medication that affects brain function to alter perception, mood or behaviour) such as SSRIs, work by affecting (increasing or inhibiting) the transmission of neurotransmitters across the synapse - Some pain medications mimic the effects of inhibitory neurotransmitters - Stimulation of postsynaptic receptors by an inhibitory neurotransmitter results in inhibition of the postsynaptic membrane - When an inhibitory neurotransmitter binds to the post-synaptic receptors it makes the post synaptic neuron less likely to fire - Due to summation, if inhibitory neurotransmitters are higher than excitatory neurotransmitters they can inhibit an action potential from occurring - Therefore, pain medications would decrease the overall activity + reducing brain activity may lead to less pain

Answer 10

- The endocrine system provides a **chemical system of communication** in the body via the blood stream - Endocrine glands produce + secrete hormones into the bloodstream which are required to regulate many bodily functions - The major glands of the endocrine system include the pituitary gland + the adrenal glands - Each gland produces different hormones which regulate activity of organs/tissues in the body

Answer 11

- Although hormones come into contact with most cells in the body, they only affect a limited number of cells known as target cells - Target cells respond to a particular hormone because they have receptors for that hormone - When enough receptor sites are stimulated by that hormone there is a physiological reaction

Answer 12

- Located in the brain - It produces hormones whose primary function is to influence the release of other hormones from other glands in the body - Is controlled by the hypothalamus (a region of the brain just above the pituitary gland) - The hypothalamus receives info from many sources about the basic functions of the body - The hypothalamus then sends a signal to the PG in the form of a releasing hormone - This causes the PG to send a stimulating hormone into the bloodstream to tell the target gland to release its hormone - As levels of this hormone rise in the bloodstream the hypothalamus shuts down production of the releasing hormone + the PG shuts down secretion of the stimulating hormone

Answer 13

1) The anterior pituitary gland releases the hormone called ACTH which regulates levels of the hormone cortisol 2) The posterior pituitary gland is responsible for releasing the hormone oxytocin which is crucial for infant/mother bonding

Answer 14

1) Adrenal Cortex 2) Adrenal Medulla

Answer 15

- This is the outer section of the adrenal gland - It produces the hormone cortisol which is produced in high amounts when someone is experiencing chronic (long-term) stress - Cortisol is also responsible for the cardiovascular system + for instance it will increase blood pressure + causes blood vessels to constrict

Answer 16

- This is the inner section of the adrenal gland which produces adrenaline = the hormone that is needed for the fight or flight response that is activated when someone is acutely (suddenly) stressed - Adrenaline increases heart rate, dilates pupils + stops digestion

Answer 17

- The sympathetic nervous system is triggered by the hypothalamus - The hypothalamus also sends a signal to the adrenal medulla (part of the adrenal glands) which responds by releasing the hormone adrenaline into the bloodstream

Answer 18

- Adrenaline will increase heart rate, constrict blood vessels, increase rate of blood flow, raise blood pressure, divert blood away from the skin, kidneys and digestive system, increase blood supply to the brain and skeletal muscles, and increase respiration and sweating - All of this prepares the body for action + fight or flight by increasing blood supply + therefore oxygen to skeletal muscles for physical action + increasing oxygen to the brain for rapid response planning

Answer 19

- When the threat has passed the parasympathetic nervous system dampens down the stress response - It slows down the heartbeat + reduces blood pressure - Digestion, which is stopped when the sympathetic NS is active, restarts

Answer 20

The F/F response makes sense from an evolutionary psychology POV because it would have helped an individual to survive by fighting or fleeing a threat

Answer 21

- Studies supports the claim that adrenaline is essential in preparing the body for stress - People who have malfunctioning adrenal glands don't have a normal F/F response to stress

Answer 22

- Gray (1988) states that the first reaction to stress is not to F/F but freeze - This involves the person stopping, looking and listening + being hyper vigilant to danger

Answer 23

- Taylor (2000) found that females tend + befriend in times of stress - Tend and befriend refers to the protection of offspring (tend) + seeking out social groups for mutual defence (befriend) - Women have the hormone oxytocin which means they are more likely to stay and protect their offspring

Answer 24

Refers to the principle that functions e.g. vision, hearing, memory, etc. have specific locations within the brain

Answer 25

- That some functions are more localised than others - The motor and somatosensory functions are highly localised to particular areas of the cortex - Other functions are more widely distributed - The language system uses several parts of the brain, although some components such as speech production may be localised (Broca’s Area)

Answer 26

- Visual Centres - Auditory Centres

Answer 27

- The visual cortex processes info such as colour + shape - In the occipital lobe of BOTH hemispheres of the brain - Visual processing starts in the retina where light enters + strikes the photoreceptors - Nerve impulses from the retina are transmitted to the brain via the optic nerve - The majority terminate in the thalamus which acts as a relay station, passing the information onto the visual cortex

Answer 28

- The auditory cortex processes info such as pitch + volume - It lies within the temporal lobe in BOTH hemispheres of the brain - The auditory pathway begins in the cochlea in the inner ear where sound waves are converted to nerve impulses which travel via the auditory nerve to the auditory cortex - Basic decoding occurs in the brain stem, the thalamus carries out further processing before impulses reach the auditory cortex

Answer 29

- The Motor Cortex - The Somatosensory Cortex

Answer 30

- Is responsible for voluntary movements - Located in the frontal lobe of BOTH brain hemispheres - Diff parts of the motor cortex control diff parts of the body - These areas are arranged logically next to one another - Damage to this area can cause a loss of muscle function/paralysis in 1 or both sides of the body (depending on which hemisphere/hemispheres have been affected)

Answer 31

- Is responsible for processing sensations such as pain and pressure - It is located in the parietal lobe of BOTH hemispheres

Answer 32

- Broca's Area - Wernicke's Area

Answer 33

- This area is named after Paul Broca who treated patients who had difficulty producing speech - He found that they had lesions to the LEFT hemisphere of the frontal lobe - Damage to the Broca’s Area causes Expressive Aphasia - This disorder affects language production but NOT understanding - Speech lacks fluency and patients have difficulty with certain words which help sentences function e.g. ‘it’ and ‘the’

Answer 34

- This area is in the LEFT hemisphere of the temporal lobe - Carl Wernicke found that patients with a lesion to this area could speak but were unable to understand language - Wernicke concluded that this area is responsible for the processing of spoken language - The Wernicke Area is connected to the Broca’s Area by a neural loop - Damage to the Wernicke’s Area causes Receptive Aphasia - This disorder leads to an impaired ability to understand language

Answer 35

- Some functions are more localised than others - Motor and somatosensory functions are highly localised to specific areas of the cortex - However, higher functions e.g. personality + consciousness are much more widely distributed - Functions such as language are too complex to be assigned to just one area + instead involve networks of brain regions

Answer 36

- Equipoteniality theory (Lashley, 1930) holds that higher mental functions are not localised - The theory also claims that intact areas of the cortex take over responsibility for a specific cognitive function following injury to the area normally responsible

Answer 37

- Dronkers (2007) re-examined the preserved brains of two of Broca’s patients - MRI scans revealed that several areas of the brain had been damaged - Lesions to the Broca’s Area cause temporary speech disruption they do not usually result in severe disruption of language - Language is a more widely distributed (and less localised) skill than originally thought

Answer 38

- Bavelier (1997) found that there are individual differences in which brain areas are responsible for certain functions - They found that diff brain areas are activated when a person is engaged in silent reading - They observed activity in the right temporal lobe, left frontal lobe + occipital lobe - This means that the function of silent reading doesn't have a specific location within the brain

Answer 39

Refers to the notion that certain functions are principally governed by 1 side of the brain

Answer 40

- That in most people language centres are lateralised to the left hemisphere - The Broca’s Area was thought to be responsible for the production of speech however this is now thought to involve a wider network than just the Broca’s Area - Damage to the Broca’s Area leads to expressive aphasia - The Wernicke’s Area is considered to play a vital role in understanding language/interpreting speech - Damage to the Wernicke’s Area leads to receptive aphasia - The right hemisphere is dominant for visuo-spatial functions + facial recognition

Answer 41

- The right hemisphere of the brain is responsible for the left hand side of the body + the left hemisphere is responsible for the right hand side of the body - If a patient is experiencing right sided paralysis this means there is lateralised damage to the left hemisphere

Answer 42

- The 2 hemispheres are connected by a bundle of nerve fibres known as the corpus callosum which enables information to be communicated between the 2 hemispheres - Many researchers suggest that the 2 hemispheres work together to perform most tasks as part of a highly integrated system

Answer 43

- It makes sense from an evolutionary perspective - It increases neural processing capacity which is adaptive - By using 1 hemisphere to engage in a particular task it leaves the other hemisphere free to engage in another function - Rogers (2004) found that hemispheric lateralisation in chickens is associated with an ability to perform 2 tasks simultaneously: finding food + being vigilant for predators

Answer 44

- Patients who have extensive damage to their left hemisphere can experience global aphasia (loss of speech production + speech comprehension) - This suggests that language is lateralised to the left hemisphere

Answer 45

- JW (a split-brain patient) developed the capacity to speak using his right hemisphere, with the result that they could speak about information presented in either the left visual field or the right visual field (although he was more fluent if information was presented in the left) - It would appear that language is not lateralised entirely to the left hemisphere (Turk, 2002)

Answer 46

- If 1 hemisphere is damaged, undamaged regions on the opposite hemisphere can compensate - Danelli (2013) reported the case of EB, a 17-year-old Italian boy who had virtually his entire left hemisphere removed at the age of 2 and a half due to a huge benign tumour - EB’s language appeared almost normal in everyday life in terms of vocabulary and grammar - However, systematic testing revealed subtle grammatical problems as well as poorer than normal scores on picture naming + reading of loan words (words adopted from another language e.g. cafe) - Language function can be largely preserved after removal of the left hemisphere in childhood but the right hemisphere can't provide by itself a perfect mastery of each component of language

Answer 47

- In the past surgeons have cut the corpus callosum to prevent the violent electrical activity caused by epileptic seizures crossing from 1 hemisphere to the other - Patients who underwent this form of surgery are often referred to as split-brain patients

Answer 48

- They investigated split-brain patients - Info from the left visual field goes into the right hemisphere whereas info from the right visual field goes into the left hemisphere - Because in split-brain patients the corpus callosum has been severed there is no way for the info presented to one hemisphere to travel to the other

Answer 49

- Patients are asked to stare at a dot in the centre of a screen + then info is presented in either the left or right visual field - They are then asked to make responses with either their left hand (right hemisphere), right hand (left hemisphere) or verbally (left hemisphere) without being able to see what their hands were doing - They may be flashed an image of a dog in their right visual field + then asked what they have seen - They will be able to answer ‘dog’ because the info will have gone into their left hemisphere where the language centres are - If a picture of a cat is shown in their left visual field + they are asked what they have seen they will not be able to say because the info has gone into their right hemisphere which has no language centres - However, they can draw a picture of a cat with their left hand because the right hemisphere controls this hand

Answer 50

Split-brain research has enabled discoveries of hemispheric lateralisation

Answer 51

Experiments on split-brain patients are highly controlled + scientific

Answer 52

- Split-brain patients have often had drug therapy for their epilepsy for much longer than others which may affect the way in which their brain works - This means the findings of split-brain research cannot be generalised to the target population

Answer 53

Many studies using split-brain patients have as few as 3 participants making it hard for results to be generalised to the target population

Answer 54

- Refers to the brain’s ability to change and adapt as a result of experience - Plasticity allows the brain to cope better with the indirect effects of brain damage such as swelling or haemorrhage following a road accident or the damage resulting from inadequate blood supply following a stroke

Answer 55

- Nerve pathways that are used frequently develop stronger connections + those that are rarely used eventually die - By developing new connections + reducing weak ones the brain is able to adapt to a changing environment - However, there is also a decline in cognitive functioning with age attributed to these changes - Boyke (2008) taught 60 year olds a new skill (juggling) + this increased grey matter in the visual cortex

Answer 56

- Kuhn (2014) compared a control group to a group who had been given video game training for at least 30 minutes a day for 2 months on the game ‘Super Mario’ - They found that playing video games caused a significant increase in grey matter in the visual cortex, hippocampus and cerebellum - Playing video games results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory + motor performance

Answer 57

- Davidson (2004) compared 8 practitioners of Tibetan meditation with 10 students who had no previous meditation experience - An EEG picked up greater gamma wave activity in the monks even before they started meditating - Gamma waves coordinate neural activity

Answer 58

- Kempermann (1998) found far more new neurons in the brains of rats in complex environments compared to those housed in basic cages - This increase in neurons was most prominent in the hippocampus which is involved in the forming of new long-term memories + the ability to navigate

Answer 59

- Maguire (2000) measured grey matter in the brains of London taxi drivers using an MRI scan - The hippocampus in taxi drivers was significantly larger than a control group + this was positively correlated with the amount of time they had spent as a taxi driver (the extent of their life experience)

Answer 60

- Is a form of plasticity - Following damage caused by trauma, the brain can redistribute or transfer functions usually performed by damaged areas to other, undamaged areas - When the brain is still maturing, recovery from trauma is more likely (Elbert et al. 2001), however the brain is capable of plasticity + functional recovery at any age - Studies have suggested that women recover from a brain injury quicker than men do

Answer 61

Transfer of functions from damaged areas of the brain to undamaged ones can occur = called neural reorganisation

Answer 62

- Growth of new neurons and/or connections (axons and dendrites) to compensate for damaged areas can also occur = called neural regeneration - Axon sprouting is part of neural regeneration, new nerve endings grow + connect with other undamaged nerve cells to form new neural pathways

Answer 63

- Spontaneous recovery from a brain injury tends to slow down after a number of weeks - So physiotherapy may be required to maintain improvements in functioning - Techniques can include movement therapy + electrical stimulation of the brain to counter deficits in motor + cognitive functioning that can be experienced following a stroke

Answer 64

- Phantom Limb Syndrome (PLS) can be used as evidence of neural reorganisation - PLS is the continued experience of sensation in a missing limb, as if it were still there - These sensations are often unpleasant + even painful - PLS is thought to be caused by neural reorganisation in the somatosensory cortex that occurs as a result of limb loss (Ramachandran and Hirstein, 1998)

Answer 65

- Hubel and Torten Wisel (1963) sewed 1 eye of a kitten shut + analysed the brain’s cortical response - They found that the visual cortex for the shut eye was not idle (as was predicted) it continued to process information from the open eye - This is further evidence that brain areas can reorganise themselves + adapt their functions - However this is not ethical as it uses animal cruelty and causes harm, pain and discomfort to the poor kitten

Answer 66

1) Post Mortem Examinations 2) FMRI 3) EEG 4) ERP

Answer 67

- Psychologists may study a person who displays an interesting behaviour while they are alive - When the person dies, the psychologists look for abnormalities in the brain that might explain their behaviour - Post-mortem studies have found a link between brain abnormalities + psychiatric disorders e.g. there is evidence of reduced glial cells in the frontal lobe of patients with depression

Answer 68

- Post-mortem studies allow for more detailed examination of anatomical + neurochemical aspects of the brain than would not be possible with other methods of studying the brain - They have enabled researchers to examine deeper regions such as the hippocampus and hypothalamus

Answer 69

- Studies using post-mortems may lack validity because people die in a variety of circumstances + at varying stages of disease - Similarly, the length of time between death, the post-mortem + drug treatments can all affect the brain

Answer 70

- Post-Mortem studies have very small sample sizes (as special permission needs to be granted) - This means the sample cannot be said to be representative of the target population + so it is problematic to generalise the findings to the wider population

Answer 71

- FMRI provides an INDIRECT measure of neural activity - It uses magnetic fields + radio waves to monitor blood flow in the brain - It measures the change in the energy released by haemoglobin, reflecting activity of the brain (oxygen consumption) to give a moving picture of the brain - Activity in regions of interest can be compared during a base line task + during a specific activity

Answer 72

FMRIs captures dynamic brain activity as opposed to a post-mortem examination which purely show the physiology of the brain

Answer 73

FMRIs have good spatial resolution (refers to the smallest feature that a measurement can detect)

Answer 74

Interpretation of fMRI is complex + is affected by poor temporal resolution (resolution of a measurement with respect to time), biased interpretation + by the base line task used

Answer 75

FMRI research is expensive leading to reduced sample sizes which negatively impact the validity of the research

Answer 76

- An EEG DIRECTLY measures GENERAL neural activity in the brain usually linked to states such as sleep and arousal - Electrodes are placed on the scalp + detect neuronal activity directly below where they are placed + differing numbers of electrodes can be used depending on focus of the research - When electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG pattern - EEG patterns of patients with epilepsy show spikes of electrical activity - EEG patterns of those with brain injury show a slowing of electrical activity

Answer 77

An EEG is useful in clinical diagnosis e.g. it can record the neural activity associated with epilepsy so that doctors can confirm the person is experiencing seizures

Answer 78

EEGs are cheaper than an fMRI so can be used more widely in research

Answer 79

EEGs have poor spatial resolution

Answer 80

- Electrodes are placed on the scalp + DIRECTLY measure neural activity (below where they are placed) in response to a SPECIFIC stimulus introduced by the researcher - ERPs are difficult to pick out from all the other electrical activity being generated within the brain - To establish a specific response to a target stimulus requires many presentations of this stimulus + the responses are then averaged together - Any extraneous neural activity that is not related to the specific stimulus will not occur consistently whereas activity linked to the stimulus will

Answer 81

- ERPs can measure the processing of a stimulus even in the absence of a behavioural response - Therefore it is possible to measure ‘covertly’ the processing of a stimulus

Answer 82

ERPs are cheaper than an fMRI so can be used more widely in research

Answer 83

ERPs have good temporal resolution (unlike FMRIs)

Answer 84

ERPs have poor spatial resolution (unlike FMRIs)

Answer 85

- Only sufficiently strong voltage changes generated across the scalp are recordable - Important electrical activity occurring deeper in the brain is not recorded - The generation of ERPs tends to be restricted to the neocortex

Answer 86

- Are cyclical changes in physiological systems - They evolved because the environments in which organisms live have cyclical changes e.g. day/night, summer/winter etc - There are 3 types of biological rhythms: circadian, ultradian and infradian

Answer 87

- Are any cycle that lasts 24 hours - Nearly all organisms possess a biological representation of the 24 hr day - These optimise an organism’s physiology + behaviour to best meet the varying demands of the day/night cycle

Answer 88

- Circadian rhythms are driven by the suprachiasmatic nuclei (SCN) in the hypothalamus - This pacemaker (controls the rate at which something occurs) must constantly be reset so that our bodies are in synchrony with the outside world - Natural light provides the input to this system, setting the SCN to the correct time in a process called photoentrainment - The SCN then uses this info to coordinate activity of circadian rhythms throughout the body

Answer 89

- Light and darkness are the external signals that determine when we feel the need to sleep + when we wake up - This rhythm dips + rises at different times of the day so that the strongest sleep drives occur between 2:00-4:00am and 1:00-3:00pm

Answer 90

- The release of melatonin from the pineal gland is at its peak during the hours of darkness - Melatonin induces sleep by inhibiting the neural mechanisms that promote wakefulness - Light supresses the production of melatonin

Answer 91

- Sleep and wakefulness are also under homeostatic control - When we have been awake for a long time homeostasis tells us that the need for sleep is increasing because of the amount of energy used up during wakefulness - This homeostatic drive for sleep increases gradually throughout the day, reaching its maximum in the late evening - Circadian rhythms keep us awake as long as there is daylight prompting us to sleep as it becomes dark - The homeostatic system tends to make us sleepier, the longer we have been awake regardless of whether it is night or day - The internal circadian rhythm will maintain a cycle of 24-25 hours even without natural light

Answer 92

- One practical application of CRs is chronotherapeutics - The time that patients take medication is very important for treatment success - It is essential that the right concentration of drug is released in the target area of the body at the time the drug is most needed - E.g. the risk of heart attack is greatest during the early morning hours after waking - Medications have been developed that are taken before the person goes to sleep but are not released until the vulnerable time of 6:00am

Answer 93

- Research on CRs has not isolated people from artificial light, because it was believed only natural light affected CRs - However, more recent research suggests this might not be true - Cziesler (1999) altered participant’s CRs down to 22 hours + up to 28 hours by using artificial light alone

Answer 94

- There are individual differences in the length of CRs - One research study found that cycles can vary from 13 to 165 hours (Czeisler, 1999) - Another individual difference in CRs is when people reach their peak - ‘Morning people’ prefer to rise early + go to bed early whereas ‘evening people’ prefer to rise late

Answer 95

- Studies of individuals who live in Artic regions, where the sun does not set in the summer months, show normal sleeping patterns despite the prolonged exposure to light - This suggests that there are occasions where the exogenous zeitgeber of light may have very little bearing on our internal biological rhythms

Answer 96

- Ultradian rhythms span a period of less than 24 hours e.g. the 5 sleep stages - Human sleep follows a pattern alternating between Rapid Eye Movement (REM) sleep (stage 5) + Non-Rapid Eye Movement (NREM) sleep (consists of stages 1, 2, 3, 4) - The cycle repeats itself every 90 mins - Each stage shows a distinct EEG pattern - As the person enters deep sleep their brainwaves slow + their breathing + heart rate decreases - During the fifth stage (REM sleep), the EEG pattern resembles that of an awake person - It is during this stage that dreaming occurs

Answer 97

- Kleitman (1969) referred to the 90 min cycle found during sleep as the Basic Rest Activity Cycle - He suggested that this 90 min cycle continues when we are awake - During the day rather than moving through the sleep stages, we move progressively from a state of alertness into a state of physiological fatigue - Studies suggest that the human mind can focus for about 90 mins + towards the end of those 90 mins the body begins to run out of resources, resulting in loss of concentration, fatigue + hunger

Answer 98

- Ericsson (2006) found support for the URs - They studied a group of elite violinists + found that among this group practise sessions were limited to 90 mins at a time - Violinists frequently napped to recover from practise with the best violinists napping more - The same pattern was found among athletics, chess players and writers - This fits with the BRAC

Answer 99

- Tucker (2007) suggests that there are individual differences in URs which are biologically determined + may even be genetic in origin - Participants were studied over 11 consecutive days + nights in a lab environment - The researchers assessed sleep duration, time taken to fall asleep + the amount of time in each sleep stage - They found differences in all of these characteristics

Answer 100

IRs span a period of longer than 24 hours + they may last weeks, months or even a year e.g. the menstrual cycle

Answer 101

- Lasts for about a month - There are considerable variations in the length of this cycle with some women experiencing a 23 day cycle + others a 36 day cycle - The average is 28 days - Hormones regulate the menstrual cycle - Ovulation occurs roughly halfway through the menstrual cycle when oestrogen levels are at their peak + usually lasts for 16-32 hours - After ovulation, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus

Answer 102

- IRs can affect behaviour - Penton-Voak (1999) found that women express a preference for feminised male faces when choosing a partner for a long-term relationship - However they showed a preference for masculinised faces during ovulation

Answer 103

- The menstrual cycle is not only governed by IRs - When several women of childbearing age live together + don't take oral contraceptives, their menstrual cycles synchronise - In one study samples of sweat were collected from one group of women + rubbed onto the upper lip of another group of women, their menstrual cycles became synchronised - This suggests that the synchronisation is affected by pheromones - Pheromones are a chemical substance produced + released into the environment by an animal which affects the behaviour of others of the same species

Answer 104

- Our internal biological rhythms must be finely tuned in order to stay in keeping with the outside world - To achieve this we have endogenous pacemakers (internal biological rhythms) + exogenous zeitgebers (external cues/factors e.g. light) which reset our biological rhythms every day

Answer 105

- The most important EP is the suprachiasmatic nuclei (SCN) - This is a tiny cluster of nerve cells in the hypothalamus - The SCN plays an important role in generating CRs - It acts as the master clock, linking other brain regions that control sleep and arousal + controlling all other biological clocks throughout the body

Answer 106

- Neurons within the SCN synchronise with each other so that their target neurons in sites elsewhere in the body receive time-coordinated signals - These peripheral clocks can maintain a CR but not for very long which is why they are controlled by the SCN - This is possible because of the SCN’s built in CR which only needs resetting when external light levels change - The SCN receives info about light levels thru the optic nerve - If our biological clock is running slow then morning light shifts the clock

Answer 107

- The SCN also regulates the manufacture + secretion of melatonin in the pineal gland via the interconnecting neural pathway - The SCN sends a signal to the pineal gland, directing it to increase production + secretion of the hormone melatonin at night + to decrease it as light levels increase in the morning - Melatonin induces sleep by inhibiting the brain mechanisms that promote wakefulness

Answer 108

- Folkard (1996) studied a uni student (Kate Aldcroft) who spent 25 days in a lab - She had no access to the EZs of light to reset the SCN - However at the end of 25 days her core temperature rhythm was still at 24 hours - This indicates that we DO NOT need the EZs of light to maintain our internal biological rhythms

Answer 109

- Kate Aldcroft’s sleep-wake cycle extended to 30 hours with periods of sleep as long as 16 hrs - This suggests that we DO need the EZs of light to maintain our internal biological rhythms

Answer 110

- The term exogenous refers to anything whose origins are outside of the organism - EZs are environmental events that are responsible for maintaining the biological clock of an organism - The most important zeitgebers for most animals is **light**

Answer 111

- Receptors in the SCN are sensitive to changes in light levels during the day + use this info to synchronise the activity of the body’s organs + glands - Light resets the internal biological clock each day keeping it on a 24-hour cycle - A protein in the retina of the eye called melanopsin which is sensitive to natural light is critical in this system

Answer 112

- When people move to a night shift or travel to a country with a different time zone their EPs try to impose their inbuilt rhythm of sleep (CR) but this is now out of synchrony with the EZ of light - Out of sync biological rhythms lead to disrupted sleep patterns, increased anxiety + decreased alertness and vigilance

Answer 113

- The vast majority of blind people who still have light perception have normal CRs - Blind people without light perception show abnormal CRs - This shows the vital role that the EZ of light levels play in maintaining our internal biological rhythms

Answer 114

Burgess (2003) found that exposure to bright light prior to an east-west flight decreased the time needed to adjust circadian rhythms to local time

Answer 115

- Studies of individuals who live in Artic regions, where the sun does not set in the summer months show normal sleeping patterns despite the prolonged exposure to light - This suggests that there are occasions where the EZ of light may have very little bearing on our internal biological rhythms