Response of the human motor cortex: An application of the functional MRI

Functional magnetic resonance imaging (fMRI) is a noninvasive imaging tool capable of localizing and measuring the activation of brain tissue. We study the effect of sequential finger tapping of the dominant hand on activation of the human motor cortex by ing fMRI on 8 right-handed normal ma volunteers. The signal intensity changes between periods of activation and resting were derived first by a threshold procedure i.e., correlation coefficient analysis. Further study included the computation of the averaged signal changes on those pixels located in the regions of interest (ROIs) with signal intensity above the statistic le (p < 0.001 ). Finally, we mapped those activated pixels back on to a structural image for display. The mean averaged signal changes in ROIs wer 6.2 ± 2.3 % (4.4-11.6 %). During the finger tapping motor task, all subjects (n=8) showed activation in the contralateral primary motor cortex. The other brain areas activated included the contralateral somatosensoty (2/8), supplementary moto (2/8), and premotor area (3/8). Occasional equivocal activation can also be the ipsilateral primary motor (2/8), supplementary moto (2/8), and premotor areas (2/8). However, none of the subjects showed activation in the ipsilateral somatosensory area. The results of this study indicates that fMRI is capable of detecting regional signal changes related to brain activity induced by motor task within the primary as well as the association motor cortex. The technique of functional imaging and quantitative analysis in this study should be able to have clinical application in aspects such as prognostic assessment of ischemic stroke or pre-surgical evaluation of brain tumour in the future.