Motor output evoked by subsaccadic stimulation of primate frontal eye fields.

Authors

Brian D Corneil, Canadian Institutes of Health Research Group in Action and Perception & Department of Physiology and Pharmacology & and Department of Psychology, University of Western Ontario, London, ON N6A 5C1, Canada & Graduate Program in Neuroscience, University of Western Ontario, London, ON N6A 5K8, CanadaFollow
James K Elsley, Canadian Institutes of Health Research Group in Action and Perception & Department of Physiology and Pharmacology
Benjamin Nagy, Canadian Institutes of Health Research Group in Action and Perception & Graduate Program in Neuroscience, University of Western Ontario, London, ON N6A 5K8, Canada
Sharon L Cushing, Department of Otolaryngology Head and Neck Surgery, University of Toronto, Toronto, ON M5G 2N2, Canada

Document Type

Article

Publication Date

3-30-2010

Journal

Proceedings of the National Academy of Sciences of the United States of America

Volume

107

Issue

13

First Page

6070

Last Page

6075

URL with Digital Object Identifier

10.1073/pnas.0911902107

Abstract

In addition to its role in shifting the line of sight, the oculomotor system is also involved in the covert orienting of visuospatial attention. Causal evidence supporting this premotor theory of attention, or oculomotor readiness hypothesis, comes from the effect of subsaccadic threshold stimulation of the oculomotor system on behavior and neural activity in the absence of evoked saccades, which parallels the effects of covert attention. Here, by recording neck-muscle activity from monkeys and systematically titrating the level of stimulation current delivered to the frontal eye fields (FEF), we show that such subsaccadic stimulation is not divorced from immediate motor output but instead evokes neck-muscle responses at latencies that approach the minimal conduction time to the motor periphery. On average, neck-muscle thresholds were approximately 25% lower than saccade thresholds, and this difference is larger for FEF sites associated with progressively larger saccades. Importantly, we commonly observed lower neck-muscle thresholds even at sites evoking saccades