Biopsychology - Ways of studying the brain Flashcards
Define spatial resolution
Level of accuracy in identifying the exact location of brain structure or brain activity in space (where activity happened)
Define temporal resolution
Level of accuracy in identifying the exact location of a brain activity in real time (when activity happened)
Explain post mortem dissection
Brains are precisely cut after treatment to give a firmer texture. Unusual brains are dissected such as brains that suffered trauma, or from individuals with mental illness. These brains are compared with neurotypical (healthy) brains.
Give an example of a famous PM
Broca’s area, responsible for language production was discovered using post mortem on a patient called Tan, who could only say Tan (expressive aphasia) . Damage in an area of the frontal lobe was found after Tans death.
Strengths of PMs
+ High spatial resolution of post mortem allows the study of microscopic brain structures down to the neuronal level
+ Theories are then generated that can be tested with other, experimental techniques
+ Post mortem techniques have been significant in the historical development of psychology’s understanding of brain functioning such as the discovery of language centers.
Limitations of PMs
- As PM is not conducted on the living brain, unusual behaviour in life and damage found is correlational (not causation) , may not be the true cause of observable behaviour during life.
- Ethics, may not have consent from the individual to have a PM after they die
Explain how fMRI (functional magnetic resonance imaging) works
fMRI detects blood flow in the brain. As more active areas of the brain need more blood (containing oxygenated haemoglobin with distinct magnetic properties) these active areas can be compared to low activation areas with a lower blood supply and displayed on an fMRI image.
Strengths of fMRI
+ good spatial resolution of approximately 1mm. Precisely identifying active brain regions and patterns of activation over time while participants complete experimental conditions.
+ Non-invasive and safe techniques for experiments compared to options that use radiation like PET scanners
Limitations 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. Also as the participant needs to be still, experiments with body movement are not possible
Explain EEG ( Electroencephalogram)
The EEG device is a collection of between 22-34 electrodes that are attached to a cap, and fitted carefully to the scalp with conductive gel.
How is data from the EEG displayed?
The read out from each electrode is the sum total of activation of the brain cortex under the electrode. This is displayed as a series of lines showing distinct patterns called brain waves.
Amplitude (size of waves) = brain wave intensity
Frequency (distance between each wave) = speed of the activation
What does EEG stand for?
Electroencephalogram
Strengths of EEG
+ Historically important in understanding brain activity in areas such as sleep research and medical diagnosis
+ Significantly cheaper than alternatives such as fMRI and able to be used in experiments in which the participant moves
+ Portable so can use it outside of the lab with subjects moving
+ Very good temporal accuracy, measuring brain activation with a resolution measured in milliseconds
Limitations of EEGs
- Poor spatial activity as pattern is sum of large number of neurons in the cortex under the electrode. Also cannot detect activity deep within the brain.
- Practical limitation= Time consuming - can take up to 30 minutes to carefully place the electrodes on the scalp
What does ERP stand for?
Even related potential
