biological rhythms and ways of studying the brain

Question 1

FMRI definition (including real word)

Answer 1

functional magnetic resonance imaging - uses magnetic field and radio signals to monitor blood flow in the brain, show activity as it occurs and measures energy released by haemoglobin, shows activity 1 second after it occurs and accurate to within 1-2mm in the brain

Question 2

strengths of FMRI

Answer 2

• non-invasive - doesnt involve radiation or inserting into the brain = safe with no negative impacts
  good spatial resolution, can discriminate between different brain regions with more accuracy, spatial resolution of 1-2mm better than other techniques

Question 3

weaknesses of FMRI

Answer 3

• poor temporal resolution, 1-4 seconds whereas EEG/ERP have 1-10 miliseconds, unable to predict with high degree of accuracy the onset of brasin activity
• dont provide a direct measure of neural activity only measure changes in blood flow = impossible to infer causation, unable to conclude whether the brain region associates with a particular function
• very costly, machines costing up to millions and a trained specialist has to be present and require their own room = impractical
• reseachers found fmri scans tend to suggest differences in brain activity when none exist as much as 70%

Question 4

EEG definition

Answer 4

measure activity through electrodes attached to the scalp, detects electrical impulses = useful in investigating different stages of sleep and diagnosing epilepsy

Question 5

ERP defintion (and real word)

Answer 5

event related potentials, brain monitored in response to a stimulus

Question 6

advantages of EEG and ERP

Answer 6

• non-invasive, dont use radiation or involve insertive techniques = safe and risk free
• cheaper than FMRI so readily available = more patients undertaking this technique which grows our understanding of the brain
• good temporal resolution, takes readings every milisecond = can look at brains activity in real time not passive = accurate measurement of electrical activity

Question 7

disadvantages of EEG and ERP

Answer 7

• poor spatial resolution, only detect the activity in superficial regions of the brain so unable to provide info on what happens in deeper regions of the brain = limited
• could be uncomfortable for p as electrodes are attached to scalp = unrepresentative readings as patients discomfort may be affecting cognitive responses to situations

Question 8

post mortem definition

Answer 8

physical examination of the brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage, e.g Broca’s work on Tan

Question 9

post mortem limitations

Answer 9

• issue of causation, the deficit a patient displays during their lifetime may not be linked to deficits found in brain, could be another illness
• many EV that can affect results, any medication they couldve been taking, their age and length of time since they died = question conclusion
• ethical issues in relation to consent, and the patients that would be carried out on people with severe deficits so maybe unable to provide fully informed consent

Question 10

post mortem strengths

Answer 10

• provide a detailed examination of the anatomical structure and neurochemical aspects that isnt possible with other techniques, can acces hypothalamus etc = deeper insight and deeper regions
• provided a wealth of info that has led to an increased understanding of the brain, e.g broca and wernicke used post mortems for localisation
• they are invasive but not as issue as theyre dead

Question 11

3 biological rhythms and time periods

Answer 11

1. ultradian = shorter than one day
2. circadian = run over a 24 hour period
3. infradian = longer than one day

Question 12

ultradian rhythms definition (sleep cycle)

Answer 12

shorter than 24 hours e.g sleep cycle, psychologists identified most individuals circulate through 5 different stages over a period of 90-120 minutes - stages 1+2 are light sleep and can be easily awoken, brain waves become slower and rhythmic (alpha) slowing further in time (theta) - stages 3+4 deeper stages involving deta waves, difficult to awaken - stage 5 is REM sleep where dreaming occurs and body becomes paralysed

Question 13

ultradian rhythms evaluations

Answer 13

• +research support, Dement and Kleitman used EEG to monitor sleep patterns of 9 p in a sleep lab controlling for alcohol and caffeine and found REM activity was consistent with dreaming = REM sleep is a stage and an important component however study lacks eco val - pressure to perform test well
• -individual differences, Tucker found large differences in how long spent in each stage of different p’s, suggests sleep cycles are biologically determined = important to take an ideographic approach when researching ultradian rhythms

Question 14

circadian rhythms definition

Answer 14

occur over a 24 hour period, e.g sleep wake cycle + body temperature, refers to cyclical nature of drowsiness leading to sleep at night and alterness and awakeness, much debate as to whether this cycle is influenced by endogenous pacemakers or exogenous zeitgebers

Question 15

circadian rhythms evaluation

Answer 15

• research has found the sleep-wake cyclle may be influenced by exogenous zeitgebers such as light, Siffre spent several extended periods of time underground deprived of exposure to natural light and sound, when he surfaced believing it was almost september it was actually mid september as his sleep-wake cycle extended to 25 hours = influenced by EV’s however lacks generalisability
• doesnt consider individual differences, children need more sleep than adults = doesnt represents variations in rhythms
• utlises case study method=lacks generalisability but good insight

Question 16

endogenous pacemakers definition

Answer 16

the suprachiasmatic nucleas (SCN) is a tiny bundle of fibres located in the hypothalamus thats implicated in the sleep-wake cycle as it acts as an EP, recieves info from the eye even when eyelids are closed SCN passes this info to the pineal gland to regulate release of melatonin to regulate tiredness (low light = more melatonin for tiredness and vice versa for light)

Question 17

exogenous zeitgebers definiton

Answer 17

external factors in our environment that influence our biological clocks through a process called entrainment, external cues e.g light and social cues, light may act as an EZ by influencing SCN - research shows light may be detected by skin receptors when not detected by eyes

Question 18

endogenous pacemakers evaluations

Answer 18

• research supporting role of SCN as an endogenous pacemaker, Decourseydetroyed SCN connections in the brains of 30 chipmunks and then returned to natural habitat and observed for 80 days and found the sleep/wake cycle of them had dissapeared and many were killed by predators for being active when they are = shows SCN regulates sleep/wake cycle
• however lacks generalisability as chipmunks have much simpler brains and lacks social factors

Question 19

evaluations of EP and EZ

Answer 19

• could be considered as interactionist systems as opposed to running as an individual system, could be considered reductionist only considering influence of one
• issues in generalising findings from animals to humans as we have much more complex brains and it raised ethical issues changing sleep/wake cycle of chipmunks

Question 20

infradian rhythms evaluations

Answer 20

• mentrual cycle can be influenced by exogenous zeitgebers such as the cycles of other women, research has found when women live in close proximity their cycles synchronise, Stern and McClintock took 29 women with irregular periods and samples of pheromones from the armpits of 9 of the women, on day 1 pads from the start were rubbed on the upper lip - found 68% of women experinced changes in their cycle closer to their ‘odour donor’ = pheromones are released and used as endogenous zeitgebers-however + of this study is the control of EV’S
• methodological limitations, stress, diet, weight etc = decreases internal val

Question 21

infradian rhythms definition

Answer 21

occur over 24 hours e.g menstrual cycle, lasts aprox 28 days during each cycle oestrogen levels rise until an egg is relseased then progesterone is relseased to thicken the womb lining if pregnancy doesnt occur then the egg is absorbed into the body and the womb line comes away

Question 22

difference between exogenous zeitgerbers and endogenous pacemakers

Answer 22

• EZ are external factors, EP are internal factors