ways of studying the brain

• 4 different ways to study the brain?

  1. fmri
  2. eeg
  3. erp
  4. post mortems
• 3 different brain scans?

  1. fmri
  2. eeg
  3. erp
• what is FMRI?

  functional magnetic resonance imaging
• what is EEG?

  electroencephalogram
• what is ERP?

  event related potentials
• define spatial resolution?

  • smallest feature/measurement that a scanner can detect
• define temporal resolution?

  • accuracy of scanner in relation of time
  • how quickly scanner can detect changes in brain activity to closest millisecond
• define invasiveness?

  • use of radiation/inserting instruments directly into brain during surgery to penetrate brain
• define causality?

  • way of measuring brains ability to detect live neural activity & create cause & effect relationship between activity stimulus
• which techniques are non invasive?

  fmri

  eeg

  erp
• which technique is invasive?

  post mortem
• example of fmri scans?

  • maguires taxi driver study
  • scanned brains of taxi drivers & non drivers when doing memory tasks
  • found that hippocampi of taxi drivers were larger than non taxi drivers
• example of eeg scans?

  • sifferes study on cave explorer who lived isolated in a cave for 6 months
  • used eeg at night to measure brain wave patterns during his sleep
  • has diagnostic purposes for epilepsy & sleep disorders
• example of erp scans?

  • libet hooked participants to erp & measured brain activity of motor regions when deciding to move finger
  • found erp showed brain activity was happening before consciously decided to move their finger
• example of post mortem?

  • hm case study
  • when he was alive he had surgery to remove hippocampus - treat his epilepsy which resulted in him being unable to form new ltm
  • post mortems allowed researchers to get greater detail of damage caused by surgery
• spatial & temporal resolution of fmri scans?

  • spatial - high 1-2mm
  • temporal - low 1-4 seconds
• spatial & temporal resolution of eeg scans?

  • spatial - low detects superficial general areas of brain
  • temporal - high milliseconds
• spatial & temporal resolution of erp scans?

  • spatial - low detects superficial general areas of brain
  • temporal - high milliseconds
• 5 steps to explain how an fmri scan works?

  1. patient lies in scanner with no metals/electronics/pacemakers as scanner uses strong magnets
  2. hb has oxygen which reacts differently to magnetic stimulation compared to when hb has no oxygen
  3. scanner uses magnet to measure amount of hb being used in different parts of brain
  4. brain uses oxygen & glucose when its active & fmri detects where hb is oxygenated
  5. produces activation map(3d image) - shows which parts of brain are active during different mental processes
• function of fmri?

  • detects changes in blood flow
• function of EEG?

  • detects small changes in electrical activity
• function of ERP?

  • records activity in response to stimulus
• difference between EEG & ERP?

  • eeg measures general brain activity whereas erp measures specific brain activity in response to a stimulus
• 4 steps to explain how an eeg works?

  1. electrodes are placed on scalp using skull cap to detect electrical activity in brain
  2. electrodes pick up information as nerve impulses generated by neurons in brain
  3. activity is digitally graphed over certain time period indicating level of activity
  4. recorded activity is analysed to identify patterns & abnormalities in brain activity
• 4 types of eeg patterns?

  1. alpha
  2. beta
  3. theta
  4. delta
• what is amplitude of eeg?

  • intensity of brain activity
• what is frequency of eeg?

  • speed of brain activity
• what is synchronised state of eegs?

  • multiple eeg signals from different brain regions shows similar patterns/rhythms at same time
• what is desynchronised state of eegs?

  • no pattern between brain patterns
• 4 steps to explain how an erp works?

  1. similar equipment to eeg & measures brain activity
  2. specific stimulus is presented to p/performance on task
  3. p asked to pay attention to specific stimulus & brain activity is measured
  4. stimulus presented several times & average response is graphed
• what is the latency period of erps?

  time between presenting stimulus & response given
• * high spatial resolution for fmris?

  • sr - extent to which scanner provides detailed image of brain
  • activation map produced highly accurate 1-2mm
  • significantly more detailed image than other techniques
  • eg maguires study used fmri over other imaging techniques - provides much more detailed image of hippocampus.
  • important as it shows us precisely wherever in brain is active during tasks/size of different localised regions
  • increases effectiveness
• X low temporal resolution for fmris?

  • tr - accuracy of scanner in terms of how long it takes between brain activity & measurement being taken
  • fmri measures brain indirectly via blood flow so tr is low 3 sec delay
  • hard to determine cause & effect
  • when a study required immediate measurements of brain activity then eeg/erp equipment is much better.
  • important as it means we might not see brain activity in real time
  • means conclusions drawn not accurately measuring what they aim to measure
  • impacts overall appropriateness
• * high temporal resolution for eegs?

  • tr - how quickly method can measure brain activity
  • this method measures brain activity via electrical impulses it means it picks up brain activity within milliseconds - real time
  • useful in siffres cave study on sleep - could see precisely how his sleep pattern had changed when living in cave.
  • important as it shows us brain activity in real time so can determine cause & effect between whats happening in environment & whats happening in terms of brain activity
  • increases effectiveness
• X low spatial resolution for eegs?

  • sr - how precisely method shows imgae of actual brain activity
  • eegs have low sr of only generic & superficial brain areas
  • means it can tell you lobe but not exact cortex where activity is happening
  • not suitable for research on localisation of brain - do not give detailed image
  • ? appropriateness
  • not able to pinpoint areas that are specifically responsible for certain functions
  • could lead to issues with establishing causation
  • questioning how valid its a diagnostic tool for neurological conditions
• * high temporal resolution for erps?

  • tr - how quickly method can measure brain activity
  • this method measures brain activity via electrical impulses
  • means it picks up brain activity within milliseconds
  • useful in libets study on free will & determinism as it could tell us precisely when brain activity occured & if it was before conscious decision.
  • important as we can precisely see when theres brain activity in particular region & in response to specific stimulus
  • allows for causality to be determined
  • increases effectiveness
• X low spatial resolution for erps?

  • sr - how precisely method shows us an image of actual brain activity
  • erps have low sr of only generic & superficial brain areas
  • means it could tell you lobe but not exact cortex where actvity is happening
  • not suitable for research on localisation of brain - dont give detailed image
  • important suggests that erps are not appropriate method on localisation research
• what is a post mortem?

  • physical examination done on a person who had psychological disorder/problems with certain mental processes & behaviour when they were alive
  • used to establish cause of any problems they had when alive
  • compared to neurotypical healthy brain
  • NOT TO DETERMINE CAUSE OF DEATH
• what are the 2 characteristics of a post mortem?

  1. anatomical - physical structure of brain
  2. neurochemistry - amount & concentration of neurotransmitters
• why is post mortem hard to determine cause & effect?

  its retrospective - looking back at persons life when they are already dead