Biopsychology

Question 1

The central nervous system

Answer 1

The central nervous system
− Two main functions:
→ Control behaviour
→ Regulation of the body’s physiological processes
− Spinal cord:
→ Relay information between the brain and the rest of the body
→ Allows the brain to monitor + regulate bodily processes e.g. digestion
→ If damaged nerves below the damage point will be cut off from the brain + stop functioning
− Brain:
→ Cerebrum – largest part of the brain, split into 2 hemispheres + each hemisphere is split into 4 lobes, outer suface = cerebral cortex + is responsible for ‘higher order’ functions
→ Cerebellum – controls motor skills + balance, coordinating the muscle to allow precise movements
→ Diencephalon – consists of the thalamus + hypothalamus, thalamus receives nerve impulses from the senses sending them to the appropriate part of the brain to be processed, hypothalamus regulates body temp, hunger + thirst, link between the endocrine system + nervous system controlling the regular release of hormones
→ Brian stem – regulates automatic features e.g. breathing + heartbeat, motor + sensory neurons travel through allowing impulses to pass between the brain + the spinal cord

Question 2

The peripheral nervous system

Answer 2

− Function = to relay nerve impulses from the CNS to the rest of the body + back again
− Somatic nervous stem:
→ Made up of pairs of cranial nerves + spinal nerves
→ Transmission of information to and from the CNS
→ Involves reflex actions
− Autonomic nervous system:
→ Regulates involuntary actions
→ Two branches that regulate the same organs but have the opposite effect on them
→ Sympathetic branch increases bodily activities
→ Parasympathetic branch maintains or decreases bodily activities

Question 3

Structure of neurons

Answer 3

− Nucleus – serves to maintain the cell + keep the neuron functional
− Dendrites – receive messages from other cells + are covered with synaptic receptor cells
− Axon – the elongated fibre that extends from the cell body to the terminal endings + transmits the neural signal, the larger the axon the faster it transmits information
− Cell body/soma – where signals from the dendrites are joined and passed on, serves to maintain the cell and keep the neuron functional
− Terminal buttons – located at the end of the neuron + responsible for sending the signal to the other neurons

Question 4

Neurons

Answer 4

− Neurons – cells that receive information + transmit it to other cells, essential part of the communication systems around the body

Question 5

Sensory neuron

Answer 5

→ Tell the rest of the brain about the eternal + internal environment by processing information taken from the senses (sensory receptors)
→ Sensory receptors can be found in various parts of the body e.g. the ears, tongue + skin
→ Convert information from sensory receptors into neural impulse which are then translated into sensations (e.g. heat) when they reach the brain
→ Unipolar – only transmit messages from the body to the brain

Question 6

Relay neuron

Answer 6

→ Carry messages from one part of the central nervous system to another
→ Connect motor + sensory neurons
→ Multipolar – both send + receive messages from many sources
→ Only exist in the brain + spinal cord (CNS)

Question 7

Motor neuron

Answer 7

→ Carry signals from the CNS – helps organs, glands + muscles to function
→ Multipolar – have the capability of both sending and receiving messages
→ Motor neurons form synapses with muscles + control their contractions, when stimulated the motor neuron releases neurotransmitters that bind to receptors on the muscle + trigger a response in the form of muscle movement
→ Muscle relaxation is caused by the inhibition of the motor neuron

Question 8

Excitatory neurotrasmitters

Answer 8

− the nervous systems ‘on-switches’ + increase the likelihood that an excitatory signal is sent to the postsynaptic cell which is more likely to fire, e.g. increased heart rate due to the activation of the muscle by noradrenaline

Question 9

Inhibitory neurotransmitters

Answer 9

− the nervous systems ‘off-switches’ + decrease the likelihood that a neuron will fire, they are generally responsible for calming the mind + body by inducing e.g. sleep + filter out unnecessary excitatory signals, e.g. serotonin + GABA

Question 10

The process of synoptic transmission

Answer 10

− Synaptic transmission is the process by which one neuron communicates with another. Information is passed down the axon of the neuron as an electrical impulse known as action potential.
− Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue. It must cross over the synaptic gap between the presynaptic neuron and post-synaptic neuron.
− At the end of the neuron (in the axon terminal) are the synaptic vesicles, which contain chemical messengers, known as neurotransmitters.
− When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters.
− Neurotransmitters then carry the signal across the synaptic gap.
− They bind to receptor sites on the post-synaptic cell, thereby completing the process of synaptic transmission.

Question 11

The endocrine system

Answer 11

− The endocrine system is composed of a series of glands which release chemicals known as hormones into the bloodstream + other bodily fluids
− Targets specific receptor cells on organs + regulates the activity of cells or organs within the body
− The endocrine system is controlled by the pituitary gland + hypothalamus + regulates by means of a ‘feedback loop’ to the hypothalamus
− Too much or too little activity of the endocrine system can lead to dysfunction

Question 12

Pituitary gland

Answer 12

The pituitary gland is likely the most important gland in your body it is crucial to growth, mental development + reproduction, it influences + controls the rest of your endocrine system

Question 13

Adrenal gland

Answer 13

The adrenal glands influence the way your body uses energy, they also release a hormone called adrenaline when you ae under stress + is essential for the fight or flight response

Question 14

Pancreas

Answer 14

Releases the insulin your body need to metabolism sugar

Question 15

Ovaries

Answer 15

Produce oestrogen + progesterone in women, also release egg cells

Question 16

Testes

Answer 16

Are located in the scrotum, produce hormones called androgens + most importantly testosterone in men

Question 17

The fight or flight response - The sympathomedullary pathway (SAM)

Answer 17

− Immediate (acute) stressors arouse the sympathetic branch of the autonomic nervous system

The hypothalamus detects stress —–
Activates the sympathetic branch of the autonomic nervous system (ANS) —–
Triggers the adrenal medulla —–
Releases adrenaline + nor-adrenaline

− Release of adrenaline results in quickening of heart rate + breathing, it also slows down digestion to conserve recourses for fight or flight
− The parasympathetic branch of the ANS returns heart rate + blood pressure to normal as well as speeding up digestion causing the body to relax

Question 18

The fight or flight response - The hypothalamic pituitary-adrenal system (HPA)

Answer 18

− If stress continues (chronic) then the hypothalamic pituitary-adrenal system is increasingly activated

The hypothalamus detects stress + releases corticotrophin releasing factor (CRF/CRH) —–
The pituitary gland secrets adrenal-corticotropin hormone (ACTH) ——
Travels to the adrenal context —–
Releases corticosteroids (eg cortisol) into the blood stream

− Cortisol maintains a steady supply of blood sugar for continued energy which enables the body to cope with the stressor
− Cortisol release increases the ability to tolerate more pain BUT can impair cognitive ability + reduce immune system performance

Question 19

Localisation of brain function

Answer 19

specific areas of the brain are associated with specific functions

Question 20

Hemispheric lateralisation

Answer 20

− the divisions of functions bet. the two (asymmetrical) hemispheres, the brain is contralateral in most people (right hemisphere deals with the left hand side of the body + visa-versa) – e.g. what you see in your right visual field is processed by the left hemisphere

Question 21

Left hemisphere

Answer 21

Contains the language centres (Broca’s + Wernicke’s areas)

Question 22

Right hemisphere

Answer 22

− Recognising emotions
→ Heller + Levy – a photo of a face that has been split so that one half of the face is smiling + the other is neutral is shown, the motions displayed in the left side of the picture is the emotion recognised by the ppts, the right hemisphere is dominant for this task + it’s the left visual field which is processed by the right side of the brain
− Spatial relations
Fink + Halligan et. Al. – if you ask someone to identify the small detail in a picture there is greater activity in the left hemisphere, looking at the picture holistically (as a whole) prompts more activity in the right hemisphere, conclusion: the left hemisphere focuses on detail vs the right hemisphere which processes overall patterns

Question 23

KEY STUDY: Phineas Gage (case study) - (localisation of the brain)

Answer 23

− Phineas worked on railways by placing dynamite into position + using a tamping iron (a metre-long rod with a diameter of 1 inch) to bed the dynamite in place using sand
− One day an accident occurred whereby the rod caused a spark + the dynamite blew up blasting the rod under his cheek bone through the back of his eye socket + out through the top of his forehead
− He recovered very well psychically + although he lost sight in his left eye there were no other apparent effects on his functioning
− However before the accident he was calm + well mannered, following the accident he exhibited unreliable hostile + rude behaviour, he used vulgar language which he never did prior to his injury
− This supports localisation as the damaged area had been responsible for functions e.g. palnning, reasoning + control

Question 24

Motor cortex

Answer 24

− Located in the frontal lobe (both hemispheres)
− Responsible for complex movements e.g. writing, swimming, playing an instrument – NOT basic actions e.g. coughing or crying
− Works by sending messages (nerve impulses via the motor neurons) to the muscles via the brainstem + spinal cord
− It is the complexity of the movement in the area that dictates how many neurons are needed not the size of the body part

Question 25

Somatosensory centres

Answer 25

− Somatosensory: sensations/touch
− Located in the parietal lobe of the brain along the postcentral gyrus (both hemispheres)
− The somatosensory cortex perceives touch, using sensory information from the skin it produces sensations of touch, pressure, pain + temperature
− More neuronal connections + therefore a larger amount of the somatosensory cortex are needed for touch sensitive areas of the body e.g. the face, particularly the lips

Question 26

Visual centres (visual cortex)

Answer 26

− The brain has two visual cortices (one in each hemisphere) the visual cortex in the right hemisphere receives input from the left hand side of the visual field and visa-versa
− Its located in the occipital lobe at the back of the brain (both hemispheres)
− Light enters the eyes is received by the retina hitting the photoreceptors (rods + cones) at the back of the retina, nerve impulses then travel down the optic nerve to the brain where they are received by the thalamus, the thalamus acts as a relay station transmitting information to the visual cortex
− Within the main visual centre there is an area called Area V1 which seems to be necessary for visual perception, research has found that individuals with damage to this area report no vision of any kind: conscious vision, visual imagery while awake or in their dreams (Hurovitz et al)
− However some research has found that damage to Area V1 can lead to a condition known as ‘blindsight’ in which individuals report no vision so appear blind but are able to locate objects in a visual field by pointing at them – this suggests that some of the processing in the visual cortex is not conscious as they respond to visual stimuli that they do not consciously see therefore they may be two types of vision: one conscious + the other unconscious
− Overgaard et al.:
→ Conducted a case study about a 31 yr old women who experienced ‘blindsight’ following damage within her visual cortex which occurred as a result of brain haemorrhage
→ Researchers tested her with tests asking her to detect a letter shown on a screen she could not identify the letter but she did report awareness of something despite seeing nothing
→ This continued with many of the stimuli + when tested statistically there was found to be a sig relationship bet awareness of stimuli + accuracy

Question 27

Auditory centres

Answer 27

− Located within the temporal lobes (both hemispheres) the information received from the right ear is processed mainly by the left hemisphere + visa-versa
− Concerned with hearing + processing sound information from both ears, information is transmitted about what the sound is + its location
− 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 in the brain
− On the journey to the cochlea to the brain nerve impulses passes through the brain stem+ thalamus:
→ In the brainstem information id processed through basic decoding i.e. duration + intensity of sound
→ In the thalamus further processing occurs of auditory stimulus + relay station
− If the primary auditory cortex in damaged it does not lead to total deafness, sounds can still be heard but if they require complex processing e.g. listening to music then this ability is compromised
− Research has found that the auditory cortex is not just involved with conscious sound it also processes auditory imagery, Meyer et al:
→ Found that when ppts watched silent films their primary auditory cortex in both hemispheres activated if a door is shut with force because they imagine a bang
→ The primary auditory cortex also processes auditory imagery

Question 28

Broca’s area

Answer 28

− Located in the posterior portion of the frontal lobe of the left hemisphere (the left hemisphere is where the most language processing in the majority of the pop is situated)
− Responsible for speech production
− Broca’s aphasia (expressive aphasia): is the term used to describe patience’s with problems producing speech
− However individuals with Broca’s aphasia are not always unable to say all words e.g. Gardner + Zurif:
→ Found that nouns + verbs seem relatively unaffected in some patients with damage in Broca’s area but other classes of words e.g. prepositions + conjunctions cannot be spoken e.g. people with Broca’s aphasia can’t read out loud ‘to be or not to be’ but can say ‘two bee oar knot two bee’

Question 29

KEY STUDY: Leborgne (case study) - (Broca’s area)

Answer 29

− Leborgne suffered with epilepsy throughout his childhood + eventually lost his ability to speak except for the word ‘Tan’
− When Broca conducted a post mortem of Leborgnes brain he found a lesion (area of damage – caused by his epilepsy) on the left frontal lobe
− As this was the only area of damage he concluded that it was the areas responsible for production of speech based on the deficit Leborgne exhibited

Question 30

Wernicke’s area

Answer 30

− Located in the posterior portion of the left temporal lobe of the left hemisphere
− Involved in understanding language + accessing words
− Wernicke’s aphasia (receptive aphasia) is an impaired ability to understand language + and inability to extract meaning from spoken or written words
− Wernicke found that patients who had damage to this area close to the auditory cortex had specific language impairments whereby they could speak but were unable to understand language + displayed anomia (when someone struggles to find the word they need)
− Wernicke also noticed that people were able to speak fluently when they were able to access words quickly suggesting that damage to this area of the brain does not affect speech production

Question 31

Interaction between the Broca’s and Wernicke’s areas (language centres)

Answer 31

− These two areas work together so we can understand + produce speech
− When someone speaks the sound travels through the ear + through the auditory cortex to the Wernicke’s area
− The motor region (located in the Broca’s area) is close to the area that controls the mouth, tongue + vocal cords
− The sensory region (located in the Wernicke’s area) is close to regions of the brain responsible for auditory + visual input
− Input from these regions is transferred to the Wernicke’s area where it is recognised as language + associated with meaning
− There is a neural loop (arcuate fasciculus) running bet. the Broca’s + Wernicke’s areas

Question 32

Evaluation of localisation of function in the brain: The holistic theory of brain function argues that localisation of function is largely incorrect :(

Answer 32

P: The holistic theory of brain function argues that localisation of function is largely incorrect
E: Research conducted by Lashley on rats brains didn’t find any specific area included in memory, it appeared to be stored all over the brain – Lashley referred to this as the equipotentiality theory (the idea that basic motor + sensory functions are localised but higher mental functions e.g. cognitive memory were not
C: This casts doubt on the idea that specific areas perform specific functions however it may be difficult to extrapolate these findings to humans as there are psychological difference bet the two species

Question 33

Evaluation of localisation of function in the brain: The fact that rehabilitation can help individuals to overcome brain trauma suggests that there is no localisation or lateralisation :(

Answer 33

P: The fact that rehabilitation can help individuals to overcome brain trauma suggests that there is no localisation or lateralisation
E: If there were task specific areas then there would be no brain plasticity, Lashley claimed that intact areas of the cortex could take over responsibility for specific cognitive function following damage to the area normally responsible for the function e.g. in the case of E.B. had his left hemisphere remove yet regained most of his language abilities
C: HOWEVER as he never fully recovered function then there is some localisation within certain areas of the brain

Question 34

Evaluation of localisation of function in the brain: Research suggests that what might be more important is how brain areas communicate with each other rather than the idea that specific brain regions control a particular cognitive process/function :(

Answer 34

P: Research suggests that what might be more important is how brain areas communicate with each other rather than the idea that specific brain regions control a particular cognitive process/function
E: Wernicke claimed that although different regions of the brain had different specialist functions there are interdependent (in order to work they must interact with each other) e.g. complex behaviours like language, reading + movement are built up gradually as a stimulus enters the brain + moves through different structures before a response is produced
C: Therefore damage to the connection bet any two points in this process results in impairments that resemble damage to the localised brain region associated with a specific function

Question 35

Evaluation of localisation of function in the brain: Language production may not be confined to Broca’s area alone. :(

Answer 35

P: Language production may not be confined to Broca’s area alone.
E: Dronkers et al. (2007) re-examined the preserved brain of Leborgne (Tan), using MRI brain imaging to reveal that other areas besides Broca’s area could have also contributed to the patients’ reduced speech abilities. Therefore, although lesions to Broca’s area alone can cause temporary speech disruption, they do not usually result in severe disruption of spoken language.
C: This suggests that language and cognition are far more complicated than once thought and involve networks of brain regions rather than being localised to specific areas

Question 36

Evaluation of localisation of function in the brain: Individual differences :(

Answer 36

P: There are individual differences in language areas in that the pattern of activation observed in response to various language activities can vary from one person to the next.
E: For example, in a study of silent reading, Bavelier et al. (1997) found a large variability in individual patterns of activation across different individuals. Other studies have found significant gender differences in the size of the brain areas associated with language – Harasty et al. (1997) found that women have proportionally larger Broca’s and Wernicke’s areas than men.
C: This suggests that the size of these areas are related to the use of language i.e. there is generally a greater use of language amongst women.

Question 37

Functional magnetic resonance imaging - fMRI (Ways of studying the brain)

Answer 37

− Measures changes in brain activity while a person performs a task
− Measures changes in blood flow in particular areas of the rain which indicates increased neural activity in those areas
− If an area of the brain becomes more active there is an increased demand for oxygen in that area – the brain responds to those extra demand by increasing blood flow by delivering oxygen in red blood cells
fMRI provides a moving picture of brain activity showing activity 1 sec after it occurs, it is also accurate to within 1-2mm in the brain

Question 38

Strengths of fMRI :) (Ways of studying the brain)

Answer 38

− It is non-invasive nor does it expose the brain to potentially harmful radiation
− It offers objective + reliable measure of psychological processed than is possible with verbal reports
It provides a moving picture which means that patterns of activity can be compare rather than just the physiology of the brain (e.g. in a CAT scan)

Question 39

Weaknesses of fMRI :( (Ways of studying the brain)

Answer 39

− The complexity of the brain activity means that interpreting an fMRI scan is a difficult task made more challenging by the time delay of the scan
− fMRI machines are expensive + they require trained operators which makes research expensive + difficult to organise
− The sample size in studies are often small due to limited availability + funding – the cost per ppts. is high which makes results difficult to generalise from
− Because fMRI measures changes in blood flow in the brain then it is not a direct measure of neural activity in particular brain areas
Critics argue that fMRI overlooks the networked nature of brain activity as it only focuses on localised brain activity

Question 40

Electroencephalogram - EEGs (Ways of studying the brain)

Answer 40

− An EEG measures electrical activity in the brain
− Electrodes placed on the scalp detect small electrical charges resulting from the activity of brain cells
− Electrodes measure the activity of the cells immediately under the electrode so using more electrodes gives a fuller picture
− EEG data can be used to detect various types of brain disorder that influence brain activity:
→ Patients with epilepsy show spikes of electrical activity
Patients with brain disease/injury show overall slowing of electrical activity

Question 41

Strengths of EEGs :) (Ways of studying the brain)

Answer 41

− It provided a recording of the brain’s activity in real time rather than I still image of the passive brain – the researcher can therefore accurately measure a particular task with the brain activity associated with it
− It is useful in clinical diagnosis e.g. by recording the abnormal neural activity associated with epilepsy
Both EEGs + ERPs are cheaper methods than scanning so they are more widely available to researchers

Question 42

Weaknesses of EEGs :( (Ways of studying the brain)

Answer 42

− It can only detect the activity in superficial regions of the brain + cannot reveal what is going on in deeper regions i.e. the hypothalamus – electrodes can be implanted in non-humans to achieve this but it is not ethically permissible to do this with humans because this would be too invasive
Electrical activity can be picked up by several neighbouring electrodes therefore the EEG signal is not useful for pinpointing the exact source of an activity

Question 43

Event-related potentials - ERPs (Ways of studying the brain)

Answer 43

− A measure of brain activity in response to a specific stimulus (using the same equipment as EEG)
− ERPs are difficult to distinguish from all the other electrical activity being generated with the brain at a given time
− To establish a specific response to a target stimulus requires many presentations of the stimulus + these 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
− Waves occurring within the first 100ms after presentation of the stimulus are ‘sensory’ ERPs as they reflect an initial response to the physical characteristics of the stimulus
ERPs generated after the first 100ms are ‘cognitive’ ERPs as they reflect the manner in which the subject evaluates the stimulus + demonstrates information processing

Question 44

Strengths of ERPs :) (Ways of studying the brain)

Answer 44

− An ERP can measure the processing od stimuli even in the absence of a behavioural response
Because ERPs provide a continuous measure of processing in response to a particular stimulus it makes it possible to determine how processing is affected by a specific experimental manipulation

Question 45

Weaknesses of ERPs :( (Ways of studying the brain)

Answer 45

− Because ERPs are so small + difficult to pick out from other electrical activity in the brain it requires a large number of trails to gain meaningful data – this places limitations in the type of question that ERP readings can realistically answer
Only sufficiently strong voltage changes generated across the scalp are recordable – important electrical activities occurring deep in the brain are not recorded meaning that the generation of ERPs tend to be restricted to the neocortex

Question 46

Post-mortem (Ways of studying the brain)

Answer 46

− Post-mortem examinations are used to establish the underlying neurobiology of a particular behaviour
− A person’s body inc. the brain is examined after death
− Examinations can be used to see where damage had occurred in the brain + how that might explain behaviour exhibited by the individual prior to death
One of the most famous cause studies is Leborgne

Question 47

Strengths of post-mortem :) (Ways of studying the brain)

Answer 47

− Allows for a more detailed examination of anatomical + neurochemical aspects of the brain than would be possible with non-invasive techniques – it enables researchers to examine deeper regions of the brain
Harrison: post-mortem studies have played a central part in our understanding of the origins of schizophrenia – researchers have discovered structural abnormalities + changes in neurotransmitter systems which are associate with the disorder

Question 48

Weaknesses of post-mortem :( (Ways of studying the brain)

Answer 48

− It is retrospective as the person is already dead – the researcher is unable to follow up on anything that arises from the post-mortem concerning a possible relationship bet brain abnormalities + cognitive functioning
Some brains may have been affected by the reason for death i.e. disease, similarly the length of time bet. death + post-mortem + age of death are possible confounding variables

Question 49

Circadian rhythms definition

Answer 49

− Biological rhythms that last about 24 hrs + are set/reset be environmental light levels

Question 50

The sleep-wake cycle (circadian rhythm)

Answer 50

− It dictates when we should be sleeping but also when we should be awake with dips + rises at different point of the day
− Our strongest sleep drive when we feel most sleepy usually occurs bet. 2-4am + 1-3pm (‘post lunch dip’) – the circadian rhythm therefore keeps us awake as long as there is daylight prompting us to sleep as it becomes dark
− The sleep-wake cycle is under homeostatic control: when we have been awake from a long period of time homeostasis tells us that the need for sleep is increasing because of the amount of energy used during wakefulness – this homeostatic drive for sleep increases gradually throughout the day reaching its max. in the late evening when most people fall asleep
− The internal circadian clock is ‘free-running’: it will maintain a cycle of about 24-25 hrs even in the absence of external causes
− Jet travel + shift work have a sig. impact on the sleep-wake cycle as they cause the biological clock (+internal physiological systems dependent on this) to become completely out of balance

Question 51

The sleep-wake cycle research (circadian rhythm)

Answer 51

− Michel Siffre – French cave explorer:
→ Siffre spent 6 months in a cave with no day light or cues as to the day or time e.g. a clock
→ He was wired up to machines that recorded various bodily functions
→ The researcher put lights on when Michel was awake + turned them off when he went to bed – he ate + slept whenever he wanted
→ Findings: he settled into a sleep-wake cycle of 25-30 hrs – this suggests that circadian rhythms persist despite isolation from natural light which demonstrates the existence of an endogenous clock BUT it also shows that external cues are important as the clock want perfectly accurate

− Aschoff + Weber:
→ Ppts were placed in an underground WWII bunker where there was an absence of environmental time cues as there were no windows but there was electric light in the bunker
→ Findings: most ppts displayed circadian rhythms bet. 24-25 hrs although some were as long as 29 hrs – shows that the cycle operates in the absence of external cues + that the natural free-running cycle is about 24-25 hrs

− Folkard et al:
→ 12 ppts lived in a temporal isolation unit for 3 weeks isolated from light + other time cues
→ The volunteers went to bed when the clock said 11:45 and got up at 7:45
→ The clock initially run normally but gradually quickened to become a 22 hr day
→ Findings: at the beginning the volunteers circadian rhythms matched the clock but as it quickened their rhythms ceased to matched the clock + continued to follow a 24 hr cycle rather than 22 hrs imposed by the experiment (except for 1 ppts)

Question 52

The sleep-wake cycle research evaluation (circadian rhythm)

Answer 52

− Evaluation of research:
→ Although ppts were isolated from variables e.g. clocks + daylight which could affect their circadian rhythm they were not isolated from artificial light
→ Czeisler et al found that it was possible to alter ppts circadian rhythms down to 22 hrs + up to 28 hrs using dim lighting
→ Individual differences e.g. cycle length (Czeisler et al suggested that cycles can vary from 13-65 hrs) + cycle onset (there are differences in terms of when circadian rhythms reach their peak – Duffy et al identified morning + evening types)
→ Age may also play a role in determining an individual’s sleep-wake cycle

Question 53

The temperature cycle (circadian rhythm)

Answer 53

− Core body temp. rises to its highest at about 6pm (38 degrees Celsius) + falls by about 2 degrees Celsius over the next 10 hrs to a low at about 4:40am
− Sleep occurs when core temp. begins to drop + alertness increases a core body temp. starts to rise in the last few hrs of sleep
− There is a slight drop in body temp. in the afternoon (2-4pm) which could explain feelings of sleepiness + cognitive behaviour
− The circadian temp. rhythm is different from the circadian sleep-wake cycle as they both peak at different times thus there must be at least 2 biological clocks
→ Hawkins + Armstrong-Esther found that nurses on shift duty were able to adjust their sleep-wake cycle quite quickly to their shift pattern but their temp. cycle took at least a week to change
− This information regarding circadian rhythms can be out use in everyday life e.g. through Chrono-therapeutics where treatment of an illness or disorder (e.g. drugs) are administered at a time of day believed to be in harmony with the body’s natural rhythms i.e. at a time when it will be more effective
→ E.g. you are at greatest risk of having a heart attack in the early hrs of the morning –aspirin would therefore be most effective if taken around 11pm as it takes bet. 2-4 hrs to peak in the blood stream
→ Cancer treatment – chromotheraphy drugs are administered at certain times of the day when good cells are less active (4am + 4pm), this results in the drug being 5x less likely to kill good healthy cells + 2x more likely to kill bad cancerous cells

Question 54

Hormone production (circadian rhythm)

Answer 54

− Hormone release follows a circadian rhythm e.g. the production + release of melatonin from the pineal gland in the brain follows a certain circadian rhythm with levels peaking during the hours of darkness + decreasing in response to light in the morning – melatonin encourages sleep
− Cortisol levels have also been found to fluctuate throughout the day + increase about an hr before a person wakes up helping with alertness

Question 55

Infradian rhythms definition

Answer 55

− Biological rhythms that last more than 24 hrs e.g. monthly cycles (e.g. the female menstrual cycle) + yearly cycles also known as circannual rhythms (e.g. seasonal affective disorder [SAD])

Question 56

Monthly cycles (Infradian rhythms)

Answer 56

− The menstrual cycle id driven by the endocrine system as hormone levels (oestrogen + progesterone) fluctuate under the control of the pituitary gland which regulate the ovaries – however exogenous zeitgebers e.g. light + odour (pheromones) are also thought to be involved
− The average length of the cycle is 28 days + ovulation occurs halfway through the menstrual cycle (14 days) when oestrogen levels peak + usually lasts for 16-32 hrs
− McClinton + Stern:
→ Investigated the effects of female pheromone (an exogenous zeitgeber) on the menstrual cycle
→ They collected daily samples of ‘odourless compounds’ (sweat) from the armpits of a group of 9 women which was then rubbed on the upper lips of a group of 20 women
→ A record was kept of the ppts menstrual cycles
→ 68% of women responded to the odourless compounds – when women received the odourless compound from the women in the latter half of their menstrual cycle their menstrual cycle was shortened + if the sweat was collected from the women at the beginning of their cycle this lengthened the cycle of those who received it
→ this shows that the menstrual cycle of women can be altered by communication via pheromones – the effects of pheromones could explain menstrual synchrony
− Menstrual synchrony may occur amongst women who spend a lot of time together as it means that there could potentially be synchronised pregnancies (given that they would be ovulating at the same time) – this means that childcare could be shared when babies are born
− However how close women have to live together + for how long for menstrual synchronisation occur is not clear + the extent to which pheromones have an effect still requires research
− It is also questionable as to whether menstrual synchronicity actually occurs or not – Wilson challenged its existence stating that experiment evidence was exaggerated
− Reinberg:
→ Documented the duration of a women menstrual cycle during + after she spent 3 months in a cave with only dim lighting
→ Her sleep-wake cycle lengthened slightly + her menstrual cycle became shorter during her stay in the cave – her menstrual cycle shortened to 25.7 days + it took a further yr. for her cycle to return to normal
→ This study shows that the levels of light in the cave could have affected the woman’s menstrual cycle – it shows how infradian biological rhythms can be influenced by exogenous zeitgebers i.e. light

Question 57

Yearly cycles (Infradian rhythms)

Answer 57

− Seasonal affective disorder (SAD) – individuals experience severe depression during the winter months + recover during the summer
− The hormones melatonin + serotonin are secreted when it is dark by the pineal glands – more darkness means more melatonin which means less serotonin (because melatonin is produced from serotonin) + low levels of serotonin are associated with depression
− Treatment: phototherapy – uses very strong light (equivalent to full daylight) in the evening +/or early morning to change levels of melatonin + serotonin, SAD sufferers have reported that daily phototherapy has relieved them of lethargy, depression + other related symptoms

Question 58

Split brain research (intro)

Answer 58

− Corpus callosum: a braid bundle of 55 million connecting nerve fibres that joins the two hemispheres of the brain allowing information received by one hemisphere to be sent to the other
− To treat sever epilepsy (in the past) surgeons cut the corpus callosum so that he epilepsy + accompanying electoral storms are contained within one hemisphere of the brain – this reduces the number of epileptic fits as the hemispheres rebounding off each other can prompt seizures

Question 59

Sperry and Gazzangia (split brain research)

Answer 59

− Sperry + Gazzangia studied split-brain patients to test the capabilities of the separate hemispheres
− In a typical study:
→ Patients fixate on a dot/cross in the centre of a screen (creating a split visual field) while information (e.g. faces, words, digits) is presented to either the left or the right visual field
→ They might be asked to make responses with either their left hand (controlled by the right hemisphere) of their right hand (controlled by the left hemisphere) or verbally (controlled by the left hemisphere) which out being able to see what their hands were doing
− Key findings:
→ Left hemisphere (right visual field): Patients could say any words that flashed to the right visual field demonstrating the left hemispheres ability to produce speech (presence of Broca’s area) + patients identified a painting of a face made up of fruit as ‘FRUITS’ instead of “FACE” demonstrating how the left hemisphere focuses on detail
→ Right hemisphere (left visual field): Patients could not say words flashed up on the left side of the screen but they could draw it with their left hand demonstrating processing of the word + patients identified a painting of a face made up of fruits as a ‘FACE” showing how the right hemisphere processes faces (+ emotions)

Question 60

Alien hand syndorme (split brain research)

Answer 60

− Karen suffered from epilepsy + at the age of 27 the decision was taken to operate + cut the connection bet. the two hemispheres by severing the corpus callosum
− After the surgery it became apparent that her left hand functioned separately from the rest of her body – she was diagnosed with alien hand syndrome
− This case study shows how movement is lateralised into two hemispheres

Question 61

Evaluation of split brain research: Brain lateralisation increases neural processing capacity :)

Answer 61

P: Brain lateralisation increases neural processing capacity – by using only one hemisphere to engage in a particular task this would leave the other hemisphere free to engage in another function
E: Rogers et al – in the domestic chicken brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously, finding food + being vigilant for predators
C: This study provided some evidence that brain lateralisation enhances brain efficiency in cognitive tasks that demand the simultaneous but different use of both hemispheres HOWEVER there is very little empirical evidence to support this assertion

Question 62

Evaluation of split brain research: Research has suggested that lateralisation of function changes with age :(

Answer 62

P: Research has suggested that lateralisation of function changes with age
E: Across many types of tasks + many brain areas lateralised patterns found in younger individuals tend to switch to bilateral patterns in healthy older adults e.g. the extent to which language is dominated by the left hemisphere is not fixed, it increases through childhood + adolescence + then this trend reverses in old age with signs of greater sharing of language function across the brain hemispheres in later life
E: This was supported by research that found that language became more lateralised to the left hemisphere with increasing age in children + adolescents but after age 25 lateralisation decreased with each decade of life
C: Therefore perhaps the extra (cognitive) processing resources of the other hemisphere compensates for general age-related declines in function

Question 63

Evaluation of split brain research: Language may not be restricted to the left hemisphere :(

Answer 63

P: Research suggests that language may not be restricted to the left hemisphere – slit-brain research had suggested that he right hemisphere was unable to handle even the most rudimentary language + that damage to the left hemisphere was far more detrimental to language function
E: However Turk et al conducted a case study of split-brain patient J.W. who developed the capacity to speck out of the right hemisphere such that J.W. can now speak about information presented to the left or right hemisphere
E: The case of E.B. further demonstrates the language capabilities of the right hemisphere, E.B.’s right hemisphere compensated for the loss of his left hemisphere in that he was found to be functioning linguistically well when tested at the age of 17 (having had his left hemisphere removed at 2½)
C: This therefore suggests that the right hemisphere is capable of processing language + developing that function when required

Question 64

Evaluation of split brain research: Flawed methodology :(

Answer 64

P: It is problematic to assume that split-brain research is not methodologically flawed
E: The extent to which split brain were indicative of normal function prior to surgery is an issue especially as the spilt brain surgery was to treat a problem within the brain – it is also possible that were other effects on the brain of the split brain surgery of that the hemispheres were not entirely disconnected for one another, some patients had experiences drug therapy for longer than others beforehand
E: Furthermore the split brain procedure is rarely carried out now days + patients who have had this procedure are not encounter in sufficient numbers to be useful for research purposes – Andrews argues that many studies involve as few as 3 ppts or just a single ppt which then makes it difficult to generalise the findings to others
C: This therefore suggest that we should be cautious when interpreting the findings of split-brain research + drawing conclusions about hemispheric lateralisation

Question 65

Evaluation of split brain research: Artificiality of Sperry + Gazzaniga’s research :(

Answer 65

P: The data of Sperry + Gazzaniga’s research were artificially produced
E: Because in real life a severed corpus callosum can be compensated for by the unrestricted use of 2 eye to enable both hemispheres to process visual stimuli rather than patients fixating on a point + different information being presented to each visual field
C: This therefore makes it difficult to generalise the findings of Sperry + Gazzaniga’s research beyond the experimental setting to explain the capabilities of split-brain patients in everyday life – they said that their research provided a useful insight into the functions of the 2 hemispheres thus developing a clearers understanding of hemispheric lateralization

Question 66

Plasticity of the brain

Answer 66

− Brain plasticity (or neuroplasticity) refers to the brains ability to change + adapt, modifying its own structure + function as a result of experience – research has demonstrated that the brain continues to create new neural pathways + alter existing ones to adapt to new experiences as a result of learning
− Neuroplasticity occur in the brain:
1. At the beginning of life – when the immature brain organises itself
2. In the case of brain injury – to compensate for lost functions or maximise remaining functions
3. Through adulthood – whenever something new is learnt + memorised

Question 67

Negative brain plasticity

Answer 67

− Negative neuroplasticity means that something in the environment of the individual is affecting the ongoing function + physical structure of the brain – these are thought to cause atrophy in the brain, a reduced number of dendrites connecting neurons + unfavourable levels of certain types of neurotransmitters
− The result is that the brain over time shrinks, becomes less efficient, is less protected (e.g. from age) + is inessentially older than it otherwise would be
− E.g. if you have experience anxiety for a number of yrs. your brain structures, the neuro pathways + neurochemistry associated with experiencing anxiety strengthen while the structures, pathways + chemistry involved in feeling relaxed + secure weaken so you become better at experiencing anxiety + less able to experience calm

Question 68

Factor promoting negative brain plasticity

Answer 68

− Poor sleep
− Mood disorder
− Substance abuse e.g. alcohol

Question 69

Factors promoting positive brain plasticity

Answer 69

− Learning a language
− Playing a musical instrument
− Learning abstract information

Question 70

Plasticity as a result of life experience

Answer 70

− New experiences enable never pathways that are used frequently to develop stringer connections whereas neurons that are rarely or never used eventually dies – the brain therefore has the ability to adapt to a changing environment

Question 71

Maguire et al (taxi drivers) - neuroplasticity

Answer 71

− Studied London taxi drivers to discover whether changes in the brain could be detected as a result of their extensive experiences of spatial navigation – the researchers compared MRI scans of 16 male London taxi drivers vs 50 male non taxi drivers
− Results: The hippocampus of the taxi drivers was sig. larger than the non-taxi drivers + hippocampal volume correlated positively with the amount of time spent as a taxi driver
− Conclusion: This study demonstrates plasticity of the hippocampus in response to environmental demands
− Further research: Maguire et al also found that London taxi drivers had a larger hippocampus (in the posterior region) than London bus drivers – this is because this region of the hippocampus is specialised in acquiring + using complex spatial information in order to navigate efficiently, taxi drivers have to navigate around London whereas bus drivers follow a limited set of routes

Question 72

The link bet. plasticity + age

Answer 72

− However there is a natural decline in cognitive functioning with age that can be attributed to changes in the brain which has motivated researchers to look as how new connections can be made to reverse this effect
− Boyke et al found evidence of bran plasticity in 60 yr. olds taught a new skill, juggling – they found increases in grey matter in the visual cortex although when practicing stopped these changes reversed supporting the idea that neurons that aren’t used eventually die

Question 73

Playing video games (neuroplasticity)

Answer 73

− Kuhn et al compared a control group with a video game training group that was trained for 2 months for at least 30 mins per day on the game super Mario
− They found a sig. increase in grey matter in various brain areas including the cortex, hippocampus + cerebellum – this increase was not evident in the control group that did not play super Mario
− The research concluded that video game training had resulted in new synaptic connections in the brain areas involved in spatial navigation, strategic planning, working memory + motor performance – skills that were important in playing the game successfully

Question 74

Meditation (neuroplasticity)

Answer 74

− Research working with Tibetan monks have discovered that meditation can change the inner workings of the brain
− Davidson et al compared 8 practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience – both groups were fitted with electrical sensors + asked to meditate for a short period
− The electrodes picked up much greater activation of gamma waves (important because they coordinate neuron activity) in monks with the students only showing a slight increase while meditating – it was concluded that meditation changes the workings of the brain in the short term + is capable of producing permanent changes as the monks showed more gamma wave activity than the control group even before they started meditating

Question 75

Functional recovery of the brain after trauma

Answer 75

− Functional recovery: the recovery of abilities + mental processes that have been comprised as a result of brain injury or disease
− Much recovery after trauma is due to anatomic compensation brought about by intensive rehabilitation
− The brain learns to compensate for function – the brain can be taught to learn how to use other working faculties in the brain to take over the functions that were lost

Question 76

Functional recovery of the brain after trauma - increased brain stimulation

Answer 76

− As neurons are damage there is an effect on neighboring neurons as they no longer have input
− This happens with the hemisphere too – damage to one hemisphere means the other hemisphere has reduced input + so functions at a lower level
If the undamaged hemisphere is stimulated recovery from a stroke can be improved as the damaged hemisphere can compensate for the loss of function in the damaged hemisphere by remodeling neuronal circuits + establishing new sensory processing

Question 77

Functional recovery of the brain after trauma - axon sprouting

Answer 77

− When an axon is damaged its connection with a neighboring neuron is lost
− In some cases other axons that already connect with that neuron will sprout extra connections to the neuron replacing the ones that have been destroyed
It helps reduce function but only if that damaged axon + compensatory axons do a similar job

Question 78

Functional recovery of the brain after trauma - denervation super-sensitivity

Answer 78

− Axons that do similar a job become aroused to a higher level to compensate for the ones that are lost
However it can have the consequence of over-sensitivity to messages e.g. pain

Question 79

Factors effecting recovery of the brain after trauma - perseverance

Answer 79

− Sometimes a function may appear to be lost but that may be because the individuals affected may not be trying + takes the view that it is unrecoverable
Taub + Berman: A monkey with a ‘deafferented limb (lost sensory input) will try not to use it, if the functioning of the other limbs become damages then it will have no other option that to use the deafferented one – the motor nerves are still connected to the limb but because the sensory nerve connecting is damages the monkey does not feel that it can move the limb

Question 80

Factors effecting recovery of the brain after trauma - physical exhaustion, stress + alcohol

Answer 80

− When function is recovered in an individual it is used with considerable effort + although the person can do task they are often fatigued by effort
Stress + alcohol consumption can negatively affect the ability to use any function that had been regained

Question 81

Factors effecting recovery of the brain after trauma - age

Answer 81

− Deterioration of the brain in old age affects the extent + speed of recovery
− Marquez de la Plata et al: Following brain trauma older patients (40 yrs.+) regained less function in treatment than younger patients + were also more likely to decline in terms of function for the 5 yrs. following the trauma
By contrast the case of E.B. illustrates the extent to which a young brain can regain functioning following severe damage

Question 82

Factors effecting recovery of the brain after trauma - gender

Answer 82

− Research suggests that women recover better from brain injury as their function is not as lateralized (concentrated in one hemisphere)
− Ratcliffe at al examined 325 patients with brain trauma for their responsiveness to cognitive skills following rehabilitations – results showed that women performed sig. better than men in tests of attention/working memory + language whereas me outperformed females in visual analytic skills, overall the results suggested a better recovery for women however the result did not control for performance pre-injury which could have influenced results
Research in this area is mixed so clear overall conclusions cannot be drawn

Question 83

Factors effecting recovery of the brain after trauma - education

Answer 83

Schneider et al:
− A study of 1769 patients who suffered from head injuries + had been treated, patients followed a rehabilitation programme + progress was monitor
− Of the 769 patients: 25% did not finish school, 51% had 12-15 yrs. of education + 25% graduated from university with an undergraduates degree
− One yr. after the injury 28% of the patients made a full recovery – 39% of the graduates were left free of disability compared to only 10% of those who had left school early
− Patients with the equivalent of a college education were 7x more likely to make a full recovery than people who did not finish school
− The researchers argues that more educated people make more effective use of their brain which strengthens them
− Conclusions: People who have remained in education longer have a greater ‘cognitive reserve’ – they are less likely to be left permanently disabled after a head injury, their brains are better able to maintain function in spite of damage which makes them more likely to regain function following a brain trauma

Question 84

Ultradian rhythms

Answer 84

− Biological rhythms that last less than 24 hrs – they occur more than once in an 24 hr period e.g. the sleep stages + basic-activity rest cycle (BRAC)

Question 85

Sleep stages (Ultradian rhythms)

Answer 85

− Each cycle of sleep consists of both REM + NREM sleep – the first 4 stages are NREM (non-rapid eye movement) + the 5th stage is REM (rapid eye movement),
− One cycle goes through all 5 stages + lasts 60 minutes – the number of sleep cycles depends on how long an individual sleeps for
− The different stages of sleep are measured by the electrical activities of the brain with each stage showing a distinct EEG pattern
− Stages 1 + 2 are light sleep
− As the person enters deep sleep (stages 3 +4) their brainwaves slow + their breathing + heart rate decreases – in deep sleep (SWS) most of the body’s physiological ‘repair work’ is undertaken + important biochemical processes occur e.g. the production of growth hormones
− During the 5th stage (REM) the EEG pattern resembles that of an awake person + it is in this stage that most dreaming occurs

Question 86

Sleep stages research - Dement + Kleitman (Ultradian rhythms)

Answer 86

− Connected 9 ppts (7 males + 2 females) to an EEG machine in a lab which took measurements throughout a night’s sleep
− Findings:
→ Everyone had periods of REM every night
→ There were high incidences of dream recall when ppts are awake during REM sleep – if awakened in the other stages very few reported dreaming
→ The brain activity of very vivid dreams was different to the less clear dreams
→ The rapid eye movements of REM sleep varied according to dream type + mirrored brain activity whilst awake + completing a similar task to the one they had dreamt about
− Criticisms: Ppts were studies in a sleep lab which could have caused an atypical reaction from ppts – the frequency of occurrence of REM sleep light be different in a non-experimental setting

Question 87

The basic rest activity cycle (Ultradian rhythms)

Answer 87

− Kleitman referred to the 90 minuet cycle of sleep as the basic rest activity cycle (BRAC) – he suggested that this ultradian rhythm continues during the day even when we are awake, we move progressively from a state of alertness into a state of physiological fatigue every 90 minuets
− Research suggests that the human mind can focus for a period if 90 mins + towards the end of these 90 mins the body begins to run out of resources resulting in loss of concentration, fatigue + hunger
− Friedman + Fisher observed the eating + drinking behaviour in a group of psychiatric patients over a period if 6 hours + found a 90 min cycle in eating + drinking behaviour supporting the BRAC

Question 88

Endogenous pacemakers

Answer 88

− Internal body clocks that regulate biological rhythms such as regular times of sleep linked to light levels e.g. the superchiasmatic nucleus (SCN) + the pineal gland + melatonin

Question 89

The suprachiasmatic nucleus (Endogenous pacemakers)

Answer 89

− This is thought to be the main endogenous pacemaker + is located in the hypothalamus just above the optic nerve
− The SCN obtains information on light from the optic nerve even when our eyes are shut as light penetrates the eyelids – special photoreceptors in the eye pick up light signals + carry them to the SCN
− If out endogenous clock is running slow the morning light shifts that clock ahead so that the rhythm is in sync with the outside world – our circadian rhythms are therefore entrained by the light
− The SCN also regulated the manufacture + secretion if melatonin in the pineal gland via an interconnecting neural pathway

Question 90

Research for the SCN (Endogenous pacemakers)

Answer 90

− Ralph et al:
→ Removed the SCN out if genetically abnormal hamsters which only had a circadian cycle of 20 hrs, they transplanted the SCN cells into rates which had no such abnormality + functioned on the normal 24 hr cycle
→ Following the transplant the circadian rhythm of the rats shortened to 20 hrs – this suggests the importance of the SCN in regulating circadian rhythms
− Morgan: Found that when the SCN from normally functioning hamsters was removed their circadian rhythms disappeared – when the SCN cells were transplanted back the rhythm returned
− DeCoursey et al:
→ Functionally removed the SCN in 30 chipmunks + then returned them to their natural habitat – they were then observed alongside chipmunks whose SCN remained intact
→ It was found that the SCN-lesioned chipmunks were much more active at nigh than the normal control group of chipmunks putting them at risk from nocturnal predators – in fact after 80 days a sig higher number of the lesioned chipmunks had been killed by weasels in comparison to the control group, presumably these chipmunks remained awake in their burrow + the weasels could hear the noise + were able to locate the chipmunks
→ This research suggest that biological rhythms have adaptive value – they allow an animal to anticipate daily environmental events e.g. patterns of light + dark

Question 91

The pineal gland and melatonin (Endogenous pacemakers)

Answer 91

− The pineal gland contains light-sensitive cells which receives signals from the SCN – when light is sensed the production of melatonin in the pineal gland in inhibited
− Melatonin induces sleep (levels of melatonin increase when light levels decreases) by inhibiting the brain mechanisms that promote wakefulness

Question 92

Exogenous zeitgebers

Answer 92

− Environmental cues/external stimuli that are responsible for entraining the biological clock of an organism

Question 93

Light (Exogenous zeitgebers)

Answer 93

− Receptors in the SCN are sensitive to changes in light levels during the day + use this information to synchronise the activity of the body’s organs + glands – light resets the internal biological clock each day keeping it in a 24 hr cycle
− Melanopsin: is a protein contained in a small number of retinal cells which is sensitive to natural light – it gauges overall brightness + sends these signals to the SCN to help reset the internal biological clock

Question 94

Support for the role of melanopsin (Exogenous zeitgebers)

Answer 94

− Some blind people are still able to reliably entrain their circadian rhythm in response to light despite a total lack of image-forming visual perception (i.e. non-functioning rods + cones) – this suggests that the pathway from the retinol cells containing melanopsin to the SCN is still intact + that there is therefore more than one visual pathway: one responsible for communisation light information + another for communicating images
− Further support comes from the fact that people without light perception show abnormal circadian entrainment

Question 95

Research into light (Exogenous zeitgebers)

Answer 95

− Campbell + Murphy:
→ Monitored the body temperatures of 15 volunteers who slept in a lab – they introduced light to them during the night by waking them at a series of intervals + shining light onto the back of their knees
→ The volunteers circadian rhythms were disrupted by up to 3 hrs suggesting that it is not necessary for light to just enter they eyes to have a physiological effect on biological rhythms
− Steel et al
→ Investigated the effects of constant daylight on circadian rhythms by monitoring 6 ppts living in isolation in the arctic for 6 weeks – the ppts kept sleep logs
→ Results showed that 5/6 ppts developed a free-running sleep/wake cycle longer than 24hrs
→ They also found that the sleep patterns were individual + no synchronised patterns emerged

Question 96

Social cues (Exogenous zeitgebers)

Answer 96

− Although light is the dominant zeitgeber human circadian rhythms may also be entrained by social stimuli + convention
− E.g. socially determined mealtimes, social activities, clocks, going to bed/waking up at time designated as appropriate for our age

Question 97

Research into jet lag (Exogenous zeitgebers)

Answer 97

− Burgess et al:
→ Exposed to bright light prior to an east-west flight decreased the time needed to readjust to local time on arrival
→ Volunteers ppts in 1/3 treatments (continuous bright light, intermittent bright light, dim light) each of which shifted their sleep wake cycle back one hr a day over three days
→ Ppts exposed to continuous bright light shifted their circadian rhythms by 2.1 hrs over the course of the study, those exposed to intermittent bright light shifted their rhythm by 1.5 hrs + those exposed to dim light shifted by 0.6 hrs
→ Ppts in the first treatment group felt sleepier 2 hrs earlier in the evening + woke 2 hrs earlier in the morning i.e. closer to the local time conditions they would find after an east-west flight