Ways of investigating the brain Flashcards
List the different ways of investigating the brain.
Functional magnetic resonance imaging (fMRI)
Electroencephalogram (EEG)
Event-related potentials (ERPs)
Post-mortem examination
What does functional magnetic resonance imaging (fMRI) do?
Measure blood flow.
Target the deoxygenated haemoglobin (active zone of the brain)
While the person performs a task
Shows the images approximately 1-4 seconds after it occurs, accurate within 1-2mm
Discovers the regions that are active during a task and compared with someone with a stroke, pathology, tumour to understand the width of the damage.
What does electroencephalogram (EEG) do?
Measure electrical activity through the scalp.
5 types of waves: alpha, beta, theta, delta and gamma. Watch the amplitude and frequency.
Records activity every millisecond.
Used to detect problems in cerebral activity: epilepsy, sleep disorder, Alzheimer’s disease.
What does event-related potentials (ERPs) do?
Uses similar equipment to EEG, electrodes attached to the scalp.
Key difference:
Stimulus is presented to a participant (for example a picture/ sound)
The researcher looks for activity related to that stimulus.
Stimulus is presented many times and an average response is graphed.
What does post-mortem examination do?
Analysis of a person’s brain following their death.
Studying the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage.
Broca, Wernicke, HM patient, Iverson examined the brains of deceased schizophrenic patients and it was found that they all had a higher concentration of dopamine, especially in the limbic system, compared with brains of people without schizophrenia.
What are the strengths of functional magnetic resonance imaging (fMRI)?
Doesn’t rely on the use of radiation.
It’s risk free because harmful products aren’t used.
Produces images that have high spatial resolution, depicting detail by the millimetre.
Provides a clear picture of how brain activity is localised.
What are the weaknesses of functional magnetic resonance imaging (fMRI)?
It’s expensive.
Can only capture a clear image if the person stays still.
Poor temporal resolution because there’s a 5-second time lag.
Only measures blood flow it can’t measure the activity of individual neurons so it can be difficult to tell the kind of brain activity is being represented on screen.
What are the strengths of electroencephalogram (EEG)?
Diagnoses conditions such as epilepsy.
Contributed in understanding of the stages involved in sleep.
High temporal resolution.
Accurately detect brain activity at a resolution of a single millisecond.
What are the weaknesses of electroencephalogram (EEG)?
Not useful for pinpointing the exact source of neural activity.
Doesn’t allow researchers to distinguish between activities originating in different but adjacent locations.
What are the strengths of event-related potentials (ERPs)?
Limitation of EEG are addressed through the use of ERPs.
Brings specificity to the measurement of neural processes.
Have excellent temporal resolution compared to fMRI.
Led to widespread use in the measurement of cognitive functions and deficits.
Researchers have been able to identify many different types of ERP and describes the precise role of these in cognitive functioning.
What are the weaknesses of event-related potentials (ERPs)?
Lack of standardisation which makes it difficult to confirm findings.
To establish pure data in ERP studies, background noise and extraneous materials must be completely eliminated.
What are the strengths of post-mortem examination?
Was vital in providing a foundation for early understanding of key processes in the brain.
Improve medical knowledge.
Help generate hypothesis.
Who relied on post-mortem studies and why?
Broca and Wernicke both relied on post-mortem studies to establish links between language, brain and behaviour.
What are the weaknesses of post-mortem examination?
Causation. Damage may not link to deficits under review but some other trauma and decay.
Ethical issues of consent from individuals before death.
Unable to provide informed consent, for example in HM’s case he lost his ability to form memories so was unable to be provided this.
