Module 2:Methods for understanding human psychophysiological activity
  Lecture 11:Magnetic resonance imaging (MRI)
 

The contemporary research outcome in behavioral sciences is full of fMRI based studies. Once again we shall discuss only few of them here. D'Esposito et al. (1997) asked the participants to generate mental images of certain words (such as tree) from memory and recorded fMRI data to find the neural basis of visual imagery. Increased activation was recorded in the left posterior temporal occipital region corresponding to the fusiform gyrus (area 37) while visualizing concrete words. The finding corroborated Farah's hypothesis that in most people the left hemisphere specializes for image generation.

Holloway et al. (2000) used fMRI for imaging neural plasticity. fMRI and somato-sensory evoked potentials (SEPs) were recorded in hemisherectomy patients and normal participants. When the nerves of the limb opposite to the removed hemisphere were stimulated few patients showed SEPs in the normal hemisphere. A passive movement of the right hand was traced to the left sensorimotor cortex whereas passive movement of the left (hemiplegic) hand showed an abnormal ipsilateral pathway. The findings indicated injury induced reorganization in the brain, thus exhibiting neural plasticity.

Dierks et al. (1999) attempted imaging auditory hallucination in paranoid schizophrenia patients. Only those patients were included whose hallucinations could be monitored within one fMRI session. The images revealed that verbal hallucinations were rooted in the patients' inner language systems as the primary auditory cortex, Broca's area, and the speech zone in the posterior temporal cortex in the left hemisphere were activated. The researchers held that the activation of the auditory cortex guide the discernment that the sound is coming from an external source.