Brian Corneil (Brain and Mind Institute, University of Western Ontario)

The oculomotor system, which rapidly moves the line of sight, is one of the best- understood motor systems. Although typically studied with the head-restrained, this system evolved to control the gaze axis in space with the head free to move. In my laboratory, we pair recordings of neck muscle activity with neurophysiological techniques (e.g., recording within the superior colliculus, or stimulation within the frontal eye fields (FEF)). Recent results demonstrate that cognitive processes that appear “covert” since the gaze axis remains stable (e.g., oculomotor preparation, or the allocation of attention) culminate in overt motor recruitment at the neck. We speculate that these results arise because of brainstem circuits that tightly govern the initiation of saccades without exerting a similar level of control on the initiation of neck muscle recruitment. This line of thinking led us to investigate neck muscle responses evoked by transcranial magnetic stimulation (TMS) of the FEF in humans, and more recently in non-human primates. In the final part of my talk, I will discuss how these results have guided our development of an animal model for TMS-FEF.