biopsychology lessons 10-13 Flashcards
what is a PET scan
positron emission tomography - radioactive tracer injected into body which travels to brain where neurones use glucose as a source of energy. most active brain regions accumulate more glucose so greater radioactivity picked up by pet scanner. this technique is invasive and takes long.
what is an fMRI scan
functional magnetic resonance imaging - measures blood flow through the concentration of oxygen in the blood stream. signal used is called blood oxygen level dependant. most active neurones use the most energy so require most oxygen.
evaluation of fMRI’s
advantages: fMRI’s don’t use radiation and they are non invasive so is risk free which encourages people to partake in studies requiring fmri’s. has good spatial resolution so you can distinguish between different brain regions with greater accuracy.
disadvantages: fmri’s don’t provide a direct measure of neural activity as they only measure changes in blood flow not causation. also fmri’s have poor temporal resolution.
what are EEG’S
electroencephalogram - provides overall view of brains electrical activity. lots of small recording electrodes attached to skull which pick up electrical activity. can detect all types of brain disorder such as epilepsy or brain diseases like alzheimer’s. epilepsy would show spike but alzheimer’s would show slowing activity. when awake and relaxed EEG shows alpha waves. when asleep shows theta and delta waves.
evaluation of EEG’S
advantages: provides recording of brain in real time rather than still image so researcher can accurately measure a particular task. EEG’S helped provide diagnosis of epilepsy.
disadvantages: can only detect activity in superficial parts of brain not deeper parts like the hippocampus. the EEG has poor spatial resolution as it can’t pinpoint the exact source of neural activity.
what are ERP’S
Event related potentials - small voltage changes in the brain that are triggered by specific stimuli such as cognitive processing. uses same recording electrodes as EEG but difference is that stimuli is presented to pps many times to help distinguish. stimuli could be familiar name and 4 unfamiliar names.
evaluation of ERP’s
advantages: an ERP can measure the processing of stimuli without a behavioural response which means the information gathered is true.
disadvantages: ERP’s have poor spatial resolution so they are unable to localise ERP’S components to specific areas of the cortex. in order to get correct data, extraneous variables must be minimised which cannot always be the case
what are post mortem examinations
also known as autopsies - researcher studies patient when they are alive and when they die they compare the brain to look for abnormalities. e.g. broca studies man who had speech problems and when he died found he had lesion in left hemisphere.
evaluation of post mortem examinations
advantages: it allows for more detailed examination of anatomical aspects which is not possible through scans. harrison claims post mortem studies played a central role in the understanding of the origins of SZ
disadvantages: ethical issues in relation to informed consent and whether or not the patient provides consent before death and it is done on patients with psychological deficits which may not be able to give consent. it is retrospective because the person is already dead so there can’t be follow ups
what is the circadian rhythm
lasts 24hrs which resets by levels of light. driven by suprachiasmatic nuclei in the hypothalamus. this pacemaker constantly resets so our bodies are in synchrony with the outside world. can be shown through sleep-wake cycle, core body temp and hormone production.
what is the sleep wake cycle
light and dark act as signals that determine when we need to sleep and when to be awake. strongest sleep drive is between 2-4am and 1-3pm. internal circadian clock maintains a cycle of 24-25 hours even in the absence of external cues.
key study to support sleep wake cycle
cave explorer michel siffre studies human internal clock. he stayed in a cave for 6 months twice with no exogenous zeitgebers so no clocks or light. after his first one he came out on 17 sep and thought it was 20 aug. second one his natural rhythm went to just over 24 hours.
what is core body temperature
core body temp is at its lowest at 4.30am and highest at 6pm. folkard demonstrated how children who had stories read to them at 3pm and 9am performed better in comprehension at 3pm.
what is hormone production
hormone release follows circadian rhythm. release of melatonin is at its peak during hours of darkness and it drops when it is light which shows it is produced once every 24hrs
evaluation of circadian rhythms
advantages: has given researchers better understanding of the consequences disruption to the circadian rhythm can have on people who work night shifts as they have reduced concentration at 6am so are more likely to make mistakes.
disadvantages: uses case studies of really small samples as they cant be generalised to the population. also in studies where they cut out natural light they kept artificial light which could alter findings.
what are ultradian rhythms
biological rhythm with more than 1 cycle in 24hrs. stages of sleep is an example. sleep cycle alternates between REM (rapid eye movement) and NREM (non rapid eye movement)
what are the stages of sleep
stages 1 and 2 are light sleep stages. during this brainwave patterns become slower and more rhythmic starting with alpha and progressing to theta.
stages 3 and 4 are deep sleep where it is difficult to wake someone up, associated with delta waves
stage 5 is REM where the body is paralysed and brain activity is like an awake person. shows theta waves
stages of sleep key study
dement and kleitman got 7 males and 2 females to report to the lab at bedtime and were connected to an EEG. pps asked not to drink caffeinated drinks for the day before sleep. they would then be woken up between 5 and 15 mins of their REM sleep and asked if they were dreaming and if they could recall it. all pps had REM sleep. they found recall was best of dreams in rem period rather than others.
evaluation of ultradian rhythms
advantages: research support from dement and kleitman. idea of basic rest activity cycle. psychologist supported BRAC as he studied group of elite violinists who had group sessions up to 90 mins. violinists frequently napped after and the best violinists napped most.
disadvantages: there are individual differences in sleep patterns which are biologically determined. study where pps studied over 11 days and nights in lab. found that each person had different sleep duration and time to fall asleep.
what are infradian rhythms
biological rhythms that span longer than 24hrs. include menstrual cycle and seasonal affective disorder
what is the menstrual cycle
female hormonal cycle. ovulation occurs at halfway through cycle when oestrogen is highest. usually lasts for 16-32 hours. after ovulation progesterone increases. roughly lasts 28 days.
evaluation of menstrual cycle
advantages: some research shows menstrual cycle is affected by exogenous zeitgebers as psychologist examined woman who spent three months in a cave with a small lamp. he found her cycle shortened from 28 to 25.7 days. research has shown cycles can be synchronised to other women’s cycles due to odour exposure as studied where sweat was rubbed on the upper lip of other women.
disadvantages: limitations due to confounding variables such as stress and diet which can affect the cycle which makes it hard to replicate findings.
what is seasonal affective disorder (SAD)
research has found a seasonal variation in mood where people become depressed in winter. melatonin is partly responsible. longer dark hours in winter leads to more melatonin produced and so more depressive symptoms.
evaluation of SAD
advantages: research has found the rates of SAD are higher in northern countries where the winter nights are longer. e.g. 10% in northern hampshire and 2% in southern florida. one of the most effective treatments is phototherapy which is a light box used to reset melatonin
disadvantages: in the same study it was found that 30% pps showed improvements when treated with placebo.
what are endogenous pacemakers
body’s internal biological clocks. most important is suprachiasmatic nucleus (SCN) which is a tiny cluster of nerve cells in hypothalamus. acts as master clock which controls sleep cycle and arousal. neurones within the SCN synchronise with each other so target neurones receive time coordinated signals
evaluation of endogenous pacemakers
advantages: SCN is very important as shown by morgan who bred a strain of hamster that had abnormal circadian rhythm of 20 hrs. neurones from abnormal hamsters transported to normal hamsters and their circadian rhythm became abnormal too and vica versa.
disadvantages: many studies carried out on animals which are unethical such as tampering with chipmunks survival and breeding abnormal hamsters.
what are exogenous zeitgebers
external cues including light that help regulate internal bodily clocks. light is the most important as receptors in the SCN are sensitive to changes in light levels. protein in retina called melanopsin is key to this. social cues is another such as meal times and research has shown that people were able to compensate sleep time by responding to mealtimes. also explains why blind people still have circadian rhythms even though they cannot see.
evaluation of exogenous zeitgebers
advantages: role of melanopsin proved by studies of blind people as the vast majority of blind subjects who have some sort of light perception have normal circadian rhythms. study found exposure to bright light prior to an east to west flight decreased the time needed to readjust.
disadvantages: Vetter found that warm light aligns sleep-wake cycles with natural dawn, while blue light aligns them with office hours. This suggests the type and source of light affect sleep-wake cycles
