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Brain imaging techniques: fMRI, EEG, MRI and localisation

Beatriz Higgins Inglés 8 fichas

FUNCTIONAL MAGNETIC RESONANCE IMAGING (or fMRI) Measures changes in the magnetic field as blood becomes deoxygenated at…

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1FUNCTIONAL MAGNETIC RESONANCE IMAGING (or fMRI) Measures changes in the magnetic field as blood becomes deoxygenated at particular sites in the brainMAGNETIC RESONANCE IMAGING (MRI)
Uses strong magnetic fields and radio waves to produce detailed images of the inside of the body
2DIFFUSION MRI OR dMRI - Allows the mapping of the diffusion process of molecules in biological tissues -Visualize anatomical connections between different partsMAGNETOENCEPHALOGRAPHY (MEG)
-Record micro magnetic changes caused by the brain electrical activity
3ELECTROENCEPHALOGRAPHY (EEG): -Record electrical activity of the brain along the scalpTranscranial magnetic stimulation (TMS):
- Apply a pulsating magnetic field to the skull over the area where you think the activity of interest occurs
-Temporarily disrupts the functioning of a particular area of the brain
4THE DECADE OF THE BRAIN (1990s) -An initiative started by G Bush -The question is whether there are specific areas of the brain associated with specific 'mental processes' - if so we can "see" them using fMRI or "disrupt" them using TMS - A lot of this research is based upon the LOCALISATION HYPOTHESIS-It is possible to find areas of the brain that control specific cognitive functions (memory, perception, thinking, reasoning, problem solving etc.)
- This is (and has been) a widespread belief ion psychology and beyong (e.g. philosophy)
- Associated with (some branches of) Evolutionary Psychology (e.g. Tooby & Cosmides)
5The localization hypothesis makes intuitive sense (and is a widespread view in pop culture) for example:vs male:
6It is widespread because: Phrenology (or cranioscopy) -Proposed the idea that one could examine ‘bumps’ on a person’s head and obtain some valid measure of their personality and/or mental abilityPhrenology (or cranioscopy)
-Phrenology welcomed in France and England (in part) to justify the inferiority of their colonial subjects
-Problems :
Size of the cranium does not reflect intelligence (blue whale ?)
Problems with defining intelligence ? Multiple intelligence ? Aesthetic, politic, logic, social, emotional….
Rich poor, white black is continuum : objectivity of the threshold ?
Moulding with plaster to make cast. This was already done by people to have their head and chest preside for posterity.
Some were done on criminals. Remember this research were done during the English and French revolution. The terror via the guillotine or just the hanging provided researcher with a lot of head from many presumed criminals, or mad people in France, but also to study benevolence so dead persons known for their altruism also had their head moulded… On living people/slaves who volunteered
7Lesion (case study 1) -Case studies of patients with damage to specific (localised) areas of the brain -Most (in)famous case - Phineas Gage. Industrial accident caused damage to his prefrontal cortical lobes (in 1848). After accident he was (allegedly) no longer able to plan ahead, pay attention, behaviour became more ‘impulsive (but see Macmillan, 2008)Lesion (case study 2)
Broca's area - discovered by Paul Broca.
One of his patients could understand speech but was unable to speak.
The speech defect caused by damage to Broca's area
Wernicke's area - discovered by Carl Wernicke in 1874.
People who suffer from neurophysiological damage to this area are unable to understand the content of words while listening, and unable to produce meaningful sentences.
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