Ways of Investigating the Brain (Biopsychology) Flashcards
fMRI scans
fMRI scans show brain activity:
• 3D scan providing structural and functional information
• shows changes in brain activity using a strong magnetic field and radio waves
1. more oxygenated blood flows to active areas of the brain
2. molecules in oxygenated blood respond differently to a magnetic field than those in deoxygenated blood
3. more active areas of the brain can be identified
The neurones sending electrical signal widen the blood vessels to allow more oxygenated blood to flow to the brain
Haemodynamic response (HR) allows the rapid deliver of blood to active neuronal tissues. The brain consumes large amounts of energy but does not have a reservoir of stored energy substrates
This type of brain scan produces a dynamic picture
Strengths of fMRI scans
fMRI provides a high resolution moving picture of brain activity. This means that patterns of activity can be compared rather than just the physiology of the brain (localisation).
Non-invasive/virtually risk free
Does not rely on radiation (like X-rays)
Weaknesses of fMRI scans
Poor temporal resolution- 5 second time-lag behind the image on the screen and the initial firing of neuronal activity.
Expensive and can only capture a clear image if the person stays still.
Can only measure blood flown the brain. It cannot home in on activity of individual neurones.
Electroencephalogram (EEG) and uses
Looks for different frequency of brain waves
EEG electrodes are specific to areas of the brain
Uses of EEG:
• Commonly used in sleep studies
• Used for studying depression and schizophrenia. A meta-analysis by Boutros et l. (2008) showed that patients suffering from schizophrenia displayed abnormal EEG wave patterns compared to controls
• Abnormal EEGs have also been identified in patients dealing with anorexia nervosa
• EEGs can be used as a diagnostic tool (potentially)
The Lobes of the Brain
• frontal
• temporal
• parietal
• occipital
Brain wave types
• Alpha
• Beta
• Delta
• Theta
Strengths of Electroencephalogram (EEG)
Invaluable in the diagnosis of conditions such as epilepsy.
Contributed to research into ultradian rhythms of sleep.
Extremely high temporal resolution can accurately detect brain activity at a resolution of a single millisecond.
Weaknesses of Electroencephalogram
The main drawback of EEG lies in the generalised nature of the information received (thousands of neurones).
Not useful for pinpointing the exact source of neural activity and does not allow researchers to distinguish between activities origination in different but adjacent locations.
Event-related potentials (ERPs)
ERPs record activity in response to a stimulus introduced by the researcher.
All extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to the specific stimuli.
Used in memory research.
Miltner et al. (2000) found that people with phobias had an ERP of a greater amplitude in response to images of the object they feared.
Strengths of Event-related Potentials
Much more specificity to the measurement of neural processes than raw EEG data.
Excellent temporal resolution.
Researchers have been able to identify any different types of ERP and describe the precise role of these in cognitive functioning- P300 component is thought to be involved in the allocation of attentional resources and the maintenance of working memory.
Weaknesses of Event-related Potentials
Lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings.
To establish pure data, background noise and extraneous material must be completely eliminated.
Post mortem examinations
Involves removing the brain, preserving it, splicing it and observing where there was damage, activity etc
requires permission
Brown et al. (1986) discovered that patients who have schizophrenia had enlarged ventricles in their brains
Strengths of Post-mortem examinations
Vital in providing a foundation for early understanding of key processes in the brain. Broca and Wernicke both used post-mortem studies to establish links between language and the brain.
Improves medical knowledge and helps generate hypotheses for further study.
Weakness of Post-mortem examinations
Causation is an issue with these investigations- observed damage may not be linked to the deficits under review but some other trauma or decay
Ethical issues- patients may not be able to give consent. For example, the case of GM who lost his ability to form memories ad was not able to provide such consent, however post-mortem research has been conducted on his brain
