ways of studying the brain Flashcards
What is the difference between spatial resolution and temporal resolution?
Spatial- level of accuracy in identifying the exact location of a brain structure, or activity in space (where activity happened)
Temporal- level of accuracy in identifying the exact location of a brain activity in time (when activity happened)
What are the 4 ways of studying the brain?
Post mortem dissection
fMRI
EEG
ERP
What happens in the post mortem dissection? (3)
Brains are precisely cut after death
Unusual brains e.g. trauma, mental illnesses, are dissected
These brains are compared with healthy brains
2 strengths and 1 weakness of post mortem dissection
+ high spatial resolution>allows the study of microscopic brain structures down to the neuronal level
+ significant in the historical development of psychologys understanding of brain functioning e.g. discovery of language centres (Broca’s area was discovered via PMD)
- not conducted on the living brain, unusual behaviour in life and damage is found correlational
What happens in fMRI?
fMRI detects blood flow in the brain
More active areas of the brain need more blood, these active areas can be compared to low activation areas with lower blood supply, and displayed on an fMRI image
2 strengths of fMRI
-Good spational resolution of approx 1mm, precisely identifying active brain regions and patterns of activation over time, whilst ppts complete experimental conditions
-Non-invasive and safe technique for experiements compared to options that use radiation e.g. PET scans
3 weaknesses of fMRI
-Poor temporal resolution, as one image is taken every few seconds and delay in blood flow after activity, many brain processes are too fast to study
-fMRI machines are expensive to build and operate
-Ppt needs to be still, experiments with body movements are not possible
What is the EEG device? (3)
Collection of electrodes that are attached to a cap, and fitted carefully to the scalp with conductive gel
The read from each electrode is the sum of activation of the brain cortex under the electrode
This is displayed as a series of lines, that shows distinct patterns -‘brain waves’
What does the amplitude show in EEGs?
What does the frequency show in EEGs?
Amplitude (size of waves)- Brain wave intensity
Frequency (distance between each wave)- Speed of the activation
3 strengths of EEGs
-Historically important in understanding brain activity in areas e.g. sleep research and medical diagnosis
-Cheaper than alternatives e.g. fMRI, and able to be used in experiments in which the ppt moves
-Very good temporal accuracy, measuring brain activation with a resolution measured in milliseconds
1 weaknesses of EEGs
Poor spatial activity, pattern is a sum of large number of neurons in the cortex under the electrode
Cannot detect activity detect activity deep within the brain
What other way of studying the brain does the ERP use the same technique and equipment?
What makes it different?
EEG
Presents a stimulus many times, creating a smooth curve of activation by combining data in a process called ‘statistical averaging’
This removed background electrical noise unrelated to the stimulus
Waveforms peaks and dips show exactly when cognitive processes in the brain happen after the stimulus is presnted
2 strengths and 1 weakness of ERP
+ Allow researchers to isolate and study how individual cognitive processes take place in the brain, compared to EEGs that only record general brain activity
+ Good temporal resolution
- Very poor spatial resolution, some processes cannot be studied by ERP as they cannot be presented a large number of times with the same response
