2.2 - Biopsycholgy (set D - Studying The Brain) Flashcards
Define spatial resolution?
How accurate we can be about identifying the exact location of a brain structure or activity
Define temporal resolution?
Level of accuracy in identifying the exact location of a brain activity when it took place
Give 4 ways of studying the brain?
- FMRI - functional magnetic resonance imaging
- EEGs - electroencephalogram
- ERPs - event related potential
- post mortem dissection
often approaches are combined and results compared to allow for more accurate research and utilisation of pro’s of all methods
Explain the method of FMRI for studying the brain?
- uses magnets to detect blood flow and changes (of oxygenated blood) in the brain
- have the patient complete tasks and detects where higher blood flow is = area is more active compared to lower activation areas with low blood supply
Give 2 advantages of using FRMI to study the brain?
- creates a very detailed image and precisely identity’s active brain regions - good spatial resolution within 1mm (advantage)
- Safer and less invasive compared to options like PET scans which use radiation (advantage)
Give 3 disadvantages of using FRMI to study the brain?
- Delay between when neurones fire and when blood reaches neurones - image taken every few seconds, not live - poor temporal resolution
- Expensive to build and operate - implications to the economy
- participant must remain still for a clear image - reduces use in any experiment that requires movement (may not be a good option for children, ADHD or claustrophobia which can make it hard to stay still)
Explain the method of EEGs for studying the brain?
- collection of between 22 and 34 electrodes attached to a cap and fitted to the scalp with conducive gel
- each electrode picks up activity of an area which is displayed as a series of lines showing distinct patterns called brain waves (amplitude show brain wave intensity frequency and speed of activation)
Give 3 advantages of using EEGs to study the brain?
- historically important in understanding brain activity in areas such as sleep and medical diagnosis
- significantly cheaper than other techniques and is portable - allowing use when looking at movement
- very high temporal validity - measures brain activation practically live within a resolution of mili seconds
Give 2 disadvantages of using EEGs to study the brain?
- Poor spatial resolution - each electrode is picking up a large area of the brain - so not precise
- only from cortex not deep within the brain
Explain the method of ERPs for studying the brain?
- uses same equipment as the EEG (electrodes attached to scalp)
- looks at responses to a particular stimulus and the brain activity is recorded each time - creating a smooth curve of activation by combing data in a process called statistical averaging (removes background electrical noise unrelated to the stimulus)
- waveforms peal and dips show exactly when cognate processes in the brain happen after the stimulus is presented, gather average of activity
Give 2 advantages of using ERPs to study the brain?
- can isolate and study individual cognitive processes taking place in the brain - EEGs record general patterns of brain activity
- good temporal validity but poor spatial resolution (advantage + disadvantage)
Explain the method of post mortem direction for studying the brain?
brains are precisely cut after treatment (treatment done to give a firmer texture) - unusual brains (such as those associated with trauma or mental illness) are compared with a typical (healthy) brain
example is case study of TAN - who it was discovered had damage to his brocas which explained the lack of language production
Give 2 advantages of using post mortem dissection to study the brain?
- only option before advancements in technology for scanning ext - improved knowledge and understanding of the Brian
can study the brain at a high spatial resolution (study brain at a microscopic level down to neuronal level - looking at cells)
Give a disadvantage of using post mortem dissection to study the brain?
- not conducted on a living brain - unusual behaviour in life and damage found in dissection is correlational (possible link - can not say one thing has caused the other)
- but can lead to hypothesis and generation of theories which can then be investigated with other experimental research using scanning technique
Define biological rhythms?
A change in the body processes or behaviour in response to cyclical changes within the environment or internal processes within the body - help us to function
3 biological rhythms
Outline and explain the biological rhythm - circadian rhythm?
- lasts about 24 hours (happens once ever 24 hours)
- example is the sleep-wake cycle
- optimises our physiology and behaviour to best meet the varying demands of the day/night cycle
Explain how biological rhythms are fine tuned and maintained?
Maintained through a combination of exogenous zeitgebers (external time giver) and endogenous pacemakers (our body clock)
- exogenous zeitgebers include external factors like light and darkness and social cues - for children it can be a nightly routine like dinner and bath
Explain the role of light (exogenous zeitgeber) in the circadian rhythm?
- light provides primary input to system
- light is first detected by the eye (sends message to the SCN in relation to brightness)
- SCN uses information to coordinate activity of the entire circadian system by signaling pineal gland which releases melatonin causing sleepiness
- when it starts getting lighter SCN signals to pineal gland to stop producing melatonin - causes you to wake up
Homeostasis also involved
Explain what the SCN is?
Involved in circadian rhythm
- bundle of nerves in the hypothalamus which influences sleep and wake
- gets info from optic nerve about light/dark
Outline a human study which supports research into the circadian rhythm - mention siffre’s cave study?
Siffre spent 61 days and nights underground in a cave with no exogenous zeitgebers - only influence was endogenous pacemakers
- natural rhythm extended to over 24 hours - naturally its probably 25 hours (suggests society has constructed 24 hours)
- thought less time had passed than it did
Outline a problem with siffre’s experiment into the circadian rhythm?
case study - involving only 1 person, who was an experienced cave explorer - may not be generalisable to everyone
Outline research into the SCN - mention DeCourseys research with chipmunks?
Destroyed the SCN connection in the brain of 30 chipmunks - then returned them to their natural habitat and observed them for 80 days - the sleep/wake cycle of the chipmunks disappeared (by the end of the study a considerable number had been killed by predators due to them being awake when they should have been sleeping)
- suggests its evolutionary - in order for us to survive
- not generalisable to humans - due to different factors eg social cues
Outline the role of the pineal gland in the circadian rhythm?
- where melatonin is made - allows SCN to control the manufacture and secretion of the hormone
- melatonin is essential to the sleep/wake cycle of
- light rescues melatonin activity - darkness increase
Define ultradian rhythms?
- take less than 24 hours (occur more than once over 24 hours)
- eg the sleep stages
Define infradian rhythm?
- take longer than 24 hours (Can be weekly, monthly or annually)
- eg the menstrual cycle
Outline and explain the menstrual cycle as an infradian rhythm - what hormones are involved and what do they do?
- involves monthly changes in hormones which control the cycle (oestrogen and progesterone)
- first day - involves the shedding of the womb lining
- during the cycle - raisin levels of oestrogen cause the ovary to develop an egg and release it (ovulation)
- after ovulation, progesterone helps the womb lining thicken to prepare the womb for pregnancy (if not pregnant - egg is absorbed into body and womb lining comes away - menstrual flow)
Outline research support for the infradian rhythm - look at the research into pheromones and menstrual cycles?
Gathered a group of woman with irregular periods - took samples of pheromones of some of the women with a cotton pad placed on the armpit (pads worn for a few hours - then treated by freezing and with alcohol) rubbed on the lips of the women (due to large presence of receptors there)
- noticed that 68% of women experienced changes to their cycle which brought them closer to the donor women
- suggests external zeitgeber involved not just an internal process governed by endogenous pacemakers
Outline research support for the infradian rhythm - look at the research into pheromones and menstrual cycles?
Gathered a group of woman with irregular periods - took samples of pheromones of some of the women with a cotton pad placed on the armpit (pads worn for a few hours - then treated by freezing and with alcohol) rubbed on the lips of the women (due to large presence of receptors there)
- noticed that 68% of women experienced changes to their cycle which brought them closer to the donor women
- suggests external zeitgeber involved not just an internal process governed by endogenous pacemakers
Explain seasonal affective disorder (SAD) as an infradian rhythm?
- melatonin secreted by the pineal gland at night - longer nights lead to increased melatonin secretion
- linked to depressive symptoms
Explain treatment for Seasonal affective disorder (SAD)?
Artificial light through phototherapy - can be used to treat SAD and result in full remission of depression
- light extremely bright
does not work for people with depression - suggests SAD is a combination of melatonin and its effect in serotonin
Outline the stages of sleep - as an example of ultradium rhythms?
- stage 1 - light sleep (easily woken - may be sensations of falling or hallucinations)
- stage 2 - deeper sleep (body and heart relaxed, harder to wake up - temperature lowered)
- stage 3 - deepest sleep (body and heart fully relaxed - very hard to wake)
- REM - brain returns to active state, body is paralysed, rapid eye movement (associated with dreaming)
after REM sleep there cycle is repeated - in REM longer than others
Explain sleep stages as an example of ultradium rhythm?
- EEG will show the frequency of waves (brain activity) - with deeper sleep there will be less frequency waves (theta and delta)
- 4 distinct states - first 3 are NREm with the final being REM (rapid eye movement) with each cycle taking 90 minutes
Outline 2 pieces of research support into sleep stages for ultradium rhythm?
- EEG recordings involving 33 participants - showed the brain waves followed a cyclical pattern, with bodily relaxation occurring during slow wave sleep and rapid eye movement during periods of high activation
- 9 participants woken at different stages in sleep cycle reported dreaming more frequency when woken in the REM stage
- found marathon runners showed longer sleep in Stage 3 (stage where physical body recovery takes place)
Explain research into the REM sleep cycle?
EEG in 10 patients recovering from drug overdose showed an increased REM sleep in Stage - suggesting REM is for mental recovery
Evaluate sleep cycles as an ultradium rhythm?
- overall pattern of sleep - but some individual differences with newborn babies spending 80% of sleep in REM where as adults its about 20-25% suggesting sleep is invoked in development and cognitive consolidation (negative)
- led to developments of technology which can help track and aid in providing better sleep - avoiding waking up in stage 4 stops people feeling groggy and disoriented (positive)
Give 3 types of biological rhythms?
- Circadian rhythm
- Ultradium rhythm
- Infradian rhythm
