1-A-1 Effects of transcranial magnetic stimulation of FEF on neurophysiological activity in contralateral FEF

Transcranial magnetic stimulation (TMS) allows non-invasive perturbation of neural activity, induced by a rapidly changing magnetic field. Both single pulse and repetitive TMS (rTMS) have been shown to modulate behavioural output. Despite being considered an important methodology in cognitive neuroscience and as a potential treatment for neurological disorders, a precise understanding of the effect of TMS on neural activity in an interconnected brain network, and how such effects influence behavior, is largely lacking. To overcome this gap, we are developing an animal model of TMS, focusing on the oculomotor network in non-human primates (NHPs). Previous work has shown that delivering single-pulse TMS to the frontal eye fields (FEF) evokes feed-forward neck muscle responses, likely through the downstream superior colliculus, that can be used to localize optimal TMS position over the frontal cortex. Now having a reliable means of delivering TMS to the FEF, we are able to apply TMS either in a rapid pattern (e.g., singleor double-pulse TMS delivered at a precise time during a behavioural task), or in a repetitive pattern (e.g., 1-Hz TMS for 10-15 minutes). Our current focus is to examine the effects of TMS of one FEF on spiking and local field potential activity in the contra-lateral FEF. NHPs are performing either an intermixed proand anti-saccade task, or a memory-guided saccade task. In several recording sessions, we tested the effects of TMS on neurophysiological activity and behaviour after-single pulse TMS at various times of task execution, or by investigating the effects of rTMS in a block design. We present preliminary results from the inter-mixed proand anti-saccade task, which revealed a diversity of effects on single unit spiking activity, further contributing to optimization of our experimental approach.