Transcranial magnetic stimulation of the human frontal eye field.

The region of cortex over which transcranial magnetic stimulation (TMS) can delay saccadic eye movement was investigated. With TMS delivered in the reaction time foreperiod of auditory-triggered saccades, saccade onset could be delayed by up to 60 ms. The area of cortex over which TMS could delay saccade onset was located near the inter-aural line, approximately 6 cm lateral to the vertex, and was situated between areas over which TMS could generate motor evoked potentials in muscles of the hand and face. It is concluded that this area corresponds to the human frontal eye field and is closely associated with the motor strip, at a level between the representations of the hand and the face, and that stimulation of this region can interfere with the programming and execution of externally triggered saccades.