High-resolution functional magnetic resonance imaging of cortical activation during tactile exploration

Cortical activation during tactile exploration of macrogeometric objects was investigated in six healthy individuals with the use of magnetic resonance imaging (MRI) sensitized to changes in cerebral blood oxygenation. Dynamic measurements of task-related signal alterations were performed at 2.0 T using a rapid gradient-echo MRI sequence (TR/TE = 63/30 ms, flip angle 10 degrees, measuring time 6 s) at high spatial resolution (0.8 x 1.6 mm(2)). Four contiguous sections (thickness 4 mm) parallel to the bicommissural plane covered the hand area of the primary sensorimotor cortex (M1, S1), the supplementary motor area (SMA), premotor areas (PMA), and superior parts of the parietal cortex (PC). Task-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. Furthermore, bilateral responses were encountered in SMA and PC, while observations within PMA remained inconsistent. These findings in single subjects readily demonstrate a highly resolved and interindividually reproducible pattern of cortical activation in relation to exploratory finger movements and associated integration of somatosensory information. (C) 1996 Wiley-Liss, Inc.