Functional MRI of human motor cortices during overt and imagined finger movements

A T₂*‐weighted echo‐planar imaging technique at 4 T was employed to produce functional maps of the human motor cortices during overt and imagined movements. Tasks required subjects either to perform or imagine a visually cued sequence of digit‐to‐thumb oppositions. The following significant functional changes were observed: (1) Contralateral primary motor cortex showed attenuated activity during the imagined tasks; (2) bilateral supplementary motor area and premotor cortices were active during both the visually instructed movements and the imagined finger movements; and (3) superior parietal cortex showed varying degrees of activation in subjects performing the movement and imagined tasks. In preliminary data, task‐related activation of the primary motor cortex during imagined finger movements was observed in all subjects, suggesting that the motor cortex may indeed have “premotor” functions in addition to its classically assigned function solely as a muscle controller.