title: Modest gaze-related discharge modulation in monkey dorsal premotor cortex during a reaching task performed with free fixation.
abstract: Recent studies have shown that gaze angle modulates reach-related neural activity in many cortical areas, including the dorsal premotor cortex (PMd), when gaze direction is experimentally controlled by lengthy periods of imposed fixation. We looked for gaze-related modulation in PMd during the brief fixations that occur when a monkey is allowed to look around freely without experimentally imposed gaze control while performing a center-out delayed arm-reaching task. During the course of the instructed-delay period, we found significant effects of gaze angle in 27-51% of PMd cells. However, for 90-95% of cells, these effects accounted for <20% of the observed discharge variance. The effect of gaze was significantly weaker than the effect of reach-related variables. In particular, cell activity during the delay period was more strongly related to the intended movement expressed in arm-related coordinates than in gaze-related coordinates. Under the same experimental conditions, many cells in medial parietal cortex exhibited much stronger gaze-related modulation and expressed intended movement in gaze-related coordinates. In summary, gaze direction-related modulation of cell activity is indeed expressed in PMd during the brief fixations that occur in natural oculomotor behavior, but its overall effect on cell activity is modest.
authors.affiliation: Centre de Recherche en Sciences Neurologiques, Université de Montréal, C.P. 6128, Succursale Centre-ville, Quebec H3C 3J7, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Cisek
authors.forename: John F
authors.initials: JF
authors.lastname: Kalaska
mesh_terms: D000200:Action Potentials; D000818:Animals; D005133:Eye Movements; D008253:Macaca mulatta; D009043:Motor Activity; D009044:Motor Cortex / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology