Lesson 9 - Studying the Brain Flashcards
Ways to Study the Brain
Post Mortem Examinations
Functional Magnetic Resonance Imaging (fMRI) Scans
Electroencephalogram (EEG)
Event Related Potentials (ERPs)
Post Mortem Examinations
Studying the brain once the person has died
Studies have found link between brain abnormalities and psychiatric disorders
E.g. evidence of reduced glial cells in frontal lobe of patients with depression
Post Mortem Examinations Evaluation Points
Detail
Validity
Generalisation
Post Mortem Examinations Evaluation
Detail
Positive
Allow for more detailed examination of anatomical and neurochemical aspects of brain which would not be possible with other methods of studying the brain
Enabled researchers to examine deeper regions, such as hippocampus and hypothalamus
Post Mortem Examinations Evaluation
Validity
Negative
People die in a variety of circumstances and at varying stages of diseases
Similarly, length of time between death and post-mortem, and drug treatments, can all affect brain
Therefore lack validity
Post Mortem Examinations Evaluation
Generalisation
Negative
Studies have small sample
Sample cannot be representative of target population
Findings cannot be extrapolated and generalised to wider population
Functional Magnetic Resonance Imaging Scans
Provide indirect measures of neural activity
Uses magnetic fields and radio waves to monitor blood flow in brain
Measures change in energy released by haemoglobin, reflecting activity of brain to give a moving picture of the brain
Activity in regions of interest can be compared during a base line task and during a specific activity
fMRI Scans Evaluation Points
Brain Activity
Spatial Resolution
Complexity
Validity
fMRI Scans Evaluation
Brain Activity
Positive
Captures brain activity as opposed to post mortem examinations which purely show physiology of brain
fMRI Scans Evaluation
Spatial Resolution
Positive
Good spatial resolution
Refers to the smallest feature that a measurement can detect
fMRI Scans Evaluation
Complexity
Negative
Interpretations are complex and are affected by poor temporal resolution (resolution of a measurement with respect to time), biased interpretations and by the base line task used
fMRI Scans Evaluation
Validity
Negative
fMRI research is expensive leading to reduced sample sizes
Negatively effects validity of research
Electroencephalogram (EEGs)
Directly measure general neural activity in brain, usually linked to states like sleep and arousal
Electrodes placed on scalp and detect neural activity below where they are placed
Differing numbers of electrodes used dependent on focus of research
When electrical signals from different electrodes are graphed, the resulting representation is called an EEG pattern
Patients with epilepsy show spokes of electrical activity
Patterns of those with brain injury show slowing electrical activity
Electroencephalogram Evaluation Points
Clinical Diagnosis
Cheaper
Spatial Resolution
Electroencephalogram Evaluation
Clinical Diagnosis
Positive
Useful in clinical diagnosis
E.g. can record neural activity associated with epilepsy so doctors can confirm person is experiencing a seizure
Electroencephalogram Evaluation
Cheap
Positive
Cheaper than an fMRI
Therefore can be more widely used in research
Electroencephalogram Evaluation
Spatial Resolution
Negative
EEGs have poor spatial resolution
Event Related Potentials (ERPs)
Electrodes placed on scalp and directly measure neural activity in response to a specific stimulus introduced by researched
ERPs are difficult to pick out from other electrical activity being generated within the brain
To establish specific response to a target stimulus, requires many presentations of this stimulus and the responses are then averaged
Any extraneous neural activity that is not related will not occur consistently, whereas activity linked to stimulus will
Event Related Potentials Evaluation Points
Measure Cheap Temporal Resolution Spatial Resolution Neocortex
Event Related Potentials Evaluation
Measure
Positive
ERPs can measure the processing of a stimulus even in the absence of a behavioural response
Therefore it is possible to measure covertly the processing of a stimulus
Event Related Potentials Evaluation
Cheap
Positive
ERPs are cheaper than an fMRI
Therefore more widely used in research
Event Related Potentials Evaluation
Temporal Resolution
Positive
ERPs have good temporal resolution unlike fMRIs
Event Related Potentials Evaluation
Spatial Resolution
Negative
ERPs have poor spatial resolution unlike fMRIs
Event Related Potentials Evaluation
Neocortex
Negative
Only sufficiently strong voltage changes generated across the scalp are recordable
Important electrical activity occurring deeper in the brain is not recorded
The generation of ERPs tend to be restricted to the neocortex
