Ways of studying the brain Flashcards
(18 cards)
What is spatial resolution?
Level of accuracy in identifying the exact location of a brain structure or brain activity in space (where activity happened)
What is temporal resolution?
Level of accuracy in identifying the exact location of a brain activity in time (when activity happened)
What is a post mortem dissection?
Analysis of a persons brain following their death.
Dissection of the brain of those who have rare disorder and have experiences unusual deficits in cognitive processes or behaviour during life time
Areas of damage examined
Involve comparison within neurotypical brain
What is a strength of post mortem examinations?
High spatial resolution
Allows study of microscopic brain structures down the neuronal level
(Broca’s area - Tan case study - Used postmortem)
What is a limitation of post mortem examinations?
Causation
Observed damage to brain may not be linked to deficits under review
Unrelated trauma or decay
Ethical issues
Cannot provide informed consent
Challenging usefulness of postmortem studies in psychological research
What is functional magnetic resonance imaging (fMRI)?
Uses large magnets
Detects blood flow in the brain
Detects magnetic variations between oxygenated and deoxygenated haemoglobin
How does fMRI work?
As more active areas of the brain need more blood - contains oxygenated hemoglobin with distinct magnetic properties
Activates areas that can be compared to low activation areas with a lower blood supply
Produces three dimensional images
Showing parts of brain that are involved in a particular mental process
What is a strength of FMRI?
Good spatial resolution - 1mm
Precisely identifying active brain regions and patterns of activation over time while participants complete experimental conditions
Non invasive and safe technique
What are negatives of FMRI scans?
Poor temporal resolution
One image is taken every few seconds
Delay of blood flow after activity
Many processes are too fast to study
(like vision less easily studied by FMRI)
Expensive to build and operate
Participant needs to be still, experiments with body movement are not possible
What is Electroencephalogram (EEG)?
Device is collection of between 22-34 electrodes that are attached to a cap, fitted carefully to the scalp with conductive gel
May indicate neurological abnormalities such as epilepsy, tumours
How does the EEG work?
Sum total of activation of the brain cortex under the electrode
Displayed as series of lines showing distinct patterns called brain waves
What is amplitude?
Size of the waves
Shows brain wave intensity
What is frequency?
The distance between each wave
Shows speed of the activation
What are positives of EEG?
Historically important
Influenced understanding brain activity in areas such as sleep research and medical diagnosis
Non invasive
Non surgical
Cheaper than alternatives
EEG - £1000s FMRI = £1Ms
Very good temporal accuracy - resolution measured in milliseconds
What are negatives of EEG?
Poor spatial activity as pattern is sum of neurons in the cortex under the electrode
Cannot detect activity deep within the brain
What is event related potential (ERP)?
Similar technique to EEG
Electrodes attached to the scalp
But presents a stimulus many times
Creating a smooth curve of activation by combining the data in a process called statistical averaging
Removes background electrical noise unrelated to the stimulus
Waveform peaks and dips show exactly when cognitive processes in brain happen after the stimulus is presented
What are positives of the ERP?
Allows researchers to isolate and study how individual process take place in the brain
EEG - records general activity
Good temporal resolution - millisecond sampling resolution
What are negatives of the ERP?
Poor spatial resolution
Some processes cannot be studies by ERP ad they cannot be presented as a large number of times with the same response
