**L9 - Studying the Brain Flashcards
POST MORTEM EXAMINATIONS and studying the brain
Psychologists may STUDY A PERSON who DISPLAYS an INTERESTING BEHAVIOUR WHEN THEY ARE ALIVE
When the person dies, the psychologists look for ABNORMALITIES IN THE BRAIN that MIGHT EXPLAIN THEIR BEHAVIOUR
POST MORTEM STUDIES have found a LINK BETWEEN BRAIN ABNORMALITIES and PSYCHIATRIC DISORDERS, for instance there is EVIDENCE OF REDUCED GLIAL CELLS IN THE FRONTAL LOBE of PATIENTS WITH DEPRESSION
+ EXAMINE DEEPER REGIONS (EVALUATION OF POST MORTEM STUDIES)
+ POST MORTEM STUDIES allow for MORE DETAILED EXAMINATION of ANATOMICAL and NEUROCHEMICAL ASPECTS OF THE BRAIN than would be possible with OTHER METHODS OF STUDYING THE BRAIN
They have enabled researchers to EXAMINE DEEPER REGIONS, such as the HIPPOCAMPUS and HYPOTHALAMUS
- LACK VALIDITY (EVALUATION OF POST MORTEM STUDIES)
- studies using POST MORTEMS may LACK VALIDITY because people DIE IN A VARIETY of CIRCUMSTANCES and at VARYING STAGES OF DISEASE
Similarly, the LENGTH OF TIME BETWEEN DEATH and the POST MORTEM, can ALL AFFECT THE BRAIN
- VERY SMALL SAMPLE SIZES (EVALUATION OF POST MORTEM STUDIES)
- post mortem studies have VERY SMALL SAMPLE SIZES (as special permission needs to be granted)
This means the SAMPLE CANNOT BE SAID TO BE REPRESENTATIVE of the TARGET POPULATION and so it is PROBLEMATIC to GENERALISE THESE FINDINGS to the WIDER POPULATION
FUNCTIONAL MAGNETIC RESONANCE IMAGING and studying the brain
FUNCTIONAL MAGNETIC RESONANCE IMAGING (fMRI) provides an INDIRECT MEASURE OF NEURAL ACTIVITY. It USES MAGNETIC FIELDS and RADIO WAVES to MONITOR BLOOD FLOW IN THE BRAIN
It measures the CHANGE IN ENERGY RELEASED BY HAEMOGLOBIN, REFLECTING ACTIVITY OF THE BRAIN (oxygen consumption) 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
+ DYNAMIC (EVALUATION OF fMRI)
+ fMRIs CAPTURES DYNAMIC BRAIN ACTIVITY as opposed to a post mortem examination which PURELY SHOW THE PHYSIOLOGY OF THE BRAIN
+ SPATIAL RESOLUTION (EVALUATION OF fMRI)
+ fMRIs have GOOD SPATIAL RESOLUTION (refers to the SMALLEST FEATURE that a MEASUREMENT CAN DETECT)
- POOR TEMPORAL RESOLUTION (EVALUATION OF fMRI)
- INTERPRETATION of fMRI is COMPLEX and is affected by POOR TEMPORAL RESOLUTION (resolution of a measurement with respect to time), BIASED INTERPRETATION, and by the LINE TASK USED
- EXPENSIVE (EVALUATION OF fMRI)
- fMRI RESEARCH is EXPENSIVE which results in REDUCED SAMPLE SIZES which NEGATIVELY IMPACT the VALIDITY OF THE RESEARCH
ELECTROENCEPHALOGRAM and studying the brain
An ELECTROENCEPHALOGRAM (EEG) DIRECTLY MEASURES GENERAL NEURAL ACTIVITY in the BRAIN, usually LINKED TO STATES SUCH AS SLEEP AND AROUSAL
ELECTRODES are PLACED ON THE SCALP and DETECT NEURONAL ACTIVITY DIRECTLY BELOW where they are PLACED
When ELECTRICAL SIGNALS from the DIFFERENT ELECTRODES are GRAPHED OVER A PERIOD OF TIME, the RESULTING REPRESENTATION is called an EEG PATTERN.
EEG PATTERNS of patients with EPILEPSY show SPIKES OF ELECTRICAL ACTIVITY. EEG PATTERNS of those with BRAIN INJURY show a SLOWING OF ELECTRICAL ACTIVITY
+ CLINICAL DIAGNOSIS (EVALUATION OF ELECTROENCEPHALOGRAM)
+ an EEG is USEFUL IN CLINICAL DIAGNOSIS, for instance it can RECORD THE NEURAL ACTIVITY ASSOCIATED WITH EPILEPSY so that doctors can CONFIRM THE PERSON IS EXPERIENCING SEIZURES
- CHEAP (EVALUATION OF ELECTROENCEPHALOGRAM)
- EEGs are CHEAPER than an fMRI SCAN so can be USED MORE WIDELY IN RESEARCH - this is useful because it also allows us to UTILISE LARGER SAMPLE SIZES IN STUDIES which INCREASES VALIDITY
- SPATIAL RESOLUTION (EVALUATION OF ELECTROENCEPHALOGRAM)
- EEGs have POOR SPATIAL RESOLUTION so although it is CHEAPER than an fMRI SCAN, you could argue that the EXTRA COST of the fMRI is WORTHWHILE as the fMRI has a BETTER SPATIAL RESOLUTION
EVENT RELATED POTENTIALS and studying the brain
ELECTRODES are PLACED ON THE SCALP and DIRECTLY MEASURE NEURAL ACTIVITY (below where they are placed) in response to a SPECIFIC STIMULUS INTRODUCED BY RESEARCHER.
EVENT RELATED POTENTIALS are DIFFICULT TO PICK OUT from ALL OF THE OTHER ELECTRICAL ACTIVITY being GENERATED IN THE BRAIN
To ESTABLISH A SPECIFIC RESPONSE to a TARGET STIMULUS, MANY PRESENTATIONS of this STIMULUS are REQUIRED, and the RESPONSES ARE THEN AVERAGED TOGETHER. Any EXTRANEOUS NEURAL ACTIVITY that is NOT RELATED to the SPECIFIC STIMULUS will NOT OCCUR CONSISTENTLY, whereas ACTIVITY LINKED TO THE STIMULUS WILL
+ COVERT MEASURING (EVALUATION OF EVENT RELATED POTENTIALS)
+ ERP can MEASURE THE PROCESSING OF A STIMULUS EVEN IN THE ABSENCE OF A BEHAVIOURAL RESPONSE
Therefore it is possible to ‘COVERTLY’ MEASURE the PROCESSING OF A STIMULUS
