Lack of oculomotor response after transcranial magnetic stimulation

In awake humans transcranial magnetic stimulation (TMS) of the brain elicits responses in skeletal muscles by stimulating the motor cortex to produce activity in the monosynaptic corticospinal tract. It has also been demonstrated that responses can be evoked in muscles supplied by the cranial nerves V, VII and XI. Short-latency ipsilateral responses are reported to be induced by direct stimulation of the peripheral cranial nerves; bilateral responses of longer latency seem to be a consequence of face-associated motor cortex stimulation. In the present study the authors investigated whether eye movements can be evoked by TMS from frontal, precentral, posterior- and inferior-parietal, occipital and temporal positions of the stimulating coil. Their findings were negative: they evoked neither short-latency ipsilateral responses from optomotor nerves nor responses of longer latency, which might have been expected after stimulation of cortical areas concerned with voluntary eye movements, particularly the front...