TACTILE STIMULATION DURING FINGER OPPOSITION DOES NOT CONTRIBUTE TO 3D FMRI BRAIN ACTIVITY PATTERN

FUNCTIONAL magnetic resonance imaging (fMRI) is a new, non-invasive te chnique to localize brain activity with a high spatial resolution. Act ivation of the motor cortex by sequential movement of the thumb to the fingers has been used extensively to validate the fMRI technique. Thi s task, however, combines motor activity (movement of thumb and finger s) with tactile stimulation (touching the finger with the thumb). In t his study we examined the contribution of tactile stimulation to the a ctivity pattern. Nine healthy subjects were instructed to touch the fi ngers with the thumb in a first task, and repeat this movement without touching the fingers in a second task. Comparison of the two activity patterns did not result in a significant difference. Therefore me con cluded that the pattern of activity associated with a fingertapping ta sk is not influenced by tactile stimulation, but is caused primarily b y motor activation and possibly by proprioceptive activity.