Ways of studying the brain Flashcards
What are fMRIs
Used to measure function and brain activity while task is being performed
Measure changes in blood flow
Increased activity: increased oxygen
Blood flow increases as O2 is delivered in RBC
Changes in blood flow —-> map out area involved in mental activity
Evaluation of fMRIs: good
Unlike PET scans, does not rely on radiation.
fMRIs evaluation: spatial resolution
Good spatial resolution
Depicts detail by 1 mm —–> possible to get a clear picture on how activity is localised to the brain.
negative evaluation on fMRIs:
Can only measure blood flow.
Cannot magnify the activity of individual neurons so can be difficult to tell what activity shown on the screen.
Not truly a quantitative measure of mental activity in area of brain.
What are EEGs:
Measure of general brain activity.
Electrodes placed on scalp and detect small electrical charges
Over time —> produces EEG graph
Helps to detect + diagnose range of disorders arrhythmic patterns etc epilepsy.
Strength of EEG: Practical application.
useful in studying stages of sleep and diagnosis of epilepsy.
Random bursts of activity easily detected.
Extremely high temporal resolution can accurately detect brain activity at resolution of single millisecond.
Limitation of EEGs
Poor spatial resolution.
Only provide generalised information.
Activity can be picked up by several electrodes so pinpointing activity is hard.
Researches can’t distinguish certain brain activities.
What are ERPs
Isolating specific neural responses from EEG report.
Identifies activities associated with motor/sensory events.
Uses statistical averaging techniques to filter extraneous variables from OG EEG recording only leaving response for specific task.
Many trials must be conducted so random activity is averaged out.
Strength of ERPs
Provides increased specificity to measurement of neural processes compared to EEGs.
Excellent temporal resolution.
Eliminate extraneous variables (not always easy to do)
Widespread use —> cognitive scientists
Limitations of ERPs
ERPs = small so often difficult to pick out from other activity in the brain.
Large number of trials need to be conducted = expensive
Limits types of questions that ERPs can realistically answer.
What are post-mortem evaluations?
Examination of brain after death
Used to establish the underlying cause of behaviour person displayed when alive.
Look for brain abnormalities which differ from control group.
E.G: Annese et al found lesions in HM’s hippocampus which prevented him from storing new memories.
Hippocampus linked to STM.
Strength of post mortems:
Allow for more detailed examination of anatomical and neurochemical elements of brain.
Not possible with less invasive methods—> fMRIs +EEGs
deepened understanding. such as more dopamine receptors in left amygdala with people who have schizophrenia —> Falkai et al
Limitations of post mortems 🧠
Causation cannot be established.
Damage can be caused by unrelated trauma or decay.
Variations of person lifestyle can impact post-mortem.
Age of death can be confounding variable. Observed damage may not be linked to behaviour under review.
Other post-mortem evaluation points.
Ethics
Retrospective data
Cultural differences
