biological rhythms and ways of studying the brain Flashcards
FMRI definition (including real word)
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
strengths of FMRI
- 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
weaknesses of FMRI
- 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%
EEG definition
measure activity through electrodes attached to the scalp, detects electrical impulses = useful in investigating different stages of sleep and diagnosing epilepsy
ERP defintion (and real word)
event related potentials, brain monitored in response to a stimulus
advantages of EEG and ERP
- 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
disadvantages of EEG and ERP
- 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
post mortem definition
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
post mortem limitations
- 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
post mortem strengths
- 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
3 biological rhythms and time periods
- ultradian = shorter than one day
- circadian = run over a 24 hour period
- infradian = longer than one day
ultradian rhythms definition (sleep cycle)
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
ultradian rhythms evaluations
- +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
circadian rhythms definition
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
circadian rhythms evaluation
- 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
