HIGH-RESOLUTION FUNCTIONAL MAGNETIC-RESONANCE-IMAGING OF CORTICAL ACTIVATION DURING TACTILE EXPLORATION

Cortical activation during tactile exploration of macrogeometric objec ts was investigated in six healthy individuals with the use of magneti c resonance imaging (MRI) sensitized to changes in cerebral blood oxyg enation. Dynamic measurements of task-related signal alterations were performed at 2.0 T using a rapid gradient-echo MRI sequence (TR/TE = 6 3/30 ms, flip angle 10 degrees, measuring time 6 s) at high spatial re solution (0.8 x 1.6 mm(2)). Four contiguous sections (thickness 4 mm) parallel to the bicommissural plane covered the hand area of the prima ry sensorimotor cortex (M1, S1), the supplementary motor area (SMA), p remotor areas (PMA), and superior parts of the parietal cortex (PC). T ask-related activation was determined by correlating signal intensity time courses with the stimulus protocol on a pixel-by-pixel basis. in contrast to predominantly contralateral M1 activation, effects in the hand area of S1 were not restricted to the contralateral side but were equally present in the posterior section of ipsilateral S1. Furthermo re, bilateral responses were encountered in SMA and PC, while observat ions within PMA remained inconsistent. These findings in single subjec ts readily demonstrate a highly resolved and interindividually reprodu cible pattern of cortical activation in relation to exploratory finger movements and associated integration of somatosensory information. (C ) 1996 Wiley-Liss, Inc.