FUNCTIONAL COOPERATIVITY OF HUMAN CORTICAL MOTOR AREAS DURING SELF-PACED SIMPLE FINGER MOVEMENTS - A HIGH-RESOLUTION MRI STUDY

Magnetic resonance imaging of changes in cerebral blood oxygenation (C BO) delineated areas of neural activation during self-paced unilateral middle finger tapping in five normal volunteers. Four contiguous imag ing sections parallel to the bicommissural plane covered the hand area of the primary sensori-motor cortex bilaterally. All measurements wer e performed at 2.0 T using rapid gradient-echo sequences (TR/TE = 63/3 0 ms) with high spatial resolution (0.8X1.6X4 mm) and both strong (40 degrees flip angle) and weak (10 degrees) radiofrequency excitation pu lses. This allows differentiation of flow and CBO contributions to the observed signal alterations. Functional cooperativity was analysed by a pixel-by-pixel correlation of signal intensity time courses with th e stimulus protocol. Areas of activation included the contralateral pr imary motor cortex, the homologue part of the primary sensory cortex, the supplementary motor area (SMA) and the lateral premotor areas in a ll volunteers. Task-related activation of ipsilateral primary motor co rtex above a threshold correlation coefficient of 0.5 was seen in two out of five volunteers (at 40 degrees) and one out of five (at 10 degr ees) when performing the right-hand task. The present MRI findings rea dily demonstrate in single subjects that the SMA is involved in self-p aced finger tapping. Only sparse activation in the ipsilateral primary motor cortex is consistent with the motor paradigm used.