title: Frames of reference for eye-head gaze shifts evoked during frontal eye field stimulation.
abstract: The frontal eye field (FEF), in the prefrontal cortex, participates in the transformation of visual signals into saccade motor commands and in eye-head gaze control. The FEF is thought to show eye-fixed visual codes in head-restrained monkeys, but it is not known how it transforms these inputs into spatial codes for head-unrestrained gaze commands. Here, we tested if the FEF influences desired gaze commands within a simple eye-fixed frame, like the superior colliculus (SC), or in more complex egocentric frames like the supplementary eye fields (SEFs). We electrically stimulated 95 FEF sites in two head-unrestrained monkeys to evoke 3D eye-head gaze shifts and then mathematically rotated these trajectories into various reference frames. In theory, each stimulation site should specify a specific spatial goal when the evoked gaze shifts are plotted in the appropriate frame. We found that these motor output frames varied site by site, mainly within the eye-to-head frame continuum. Thus, consistent with the intermediate placement of the FEF within the high-level circuits for gaze control, its stimulation-evoked output showed an intermediate trend between the multiple reference frame codes observed in SEF-evoked gaze shifts and the simpler eye-fixed reference frame observed in SC-evoked movements. These results suggest that, although the SC, FEF and SEF carry eye-fixed information at the level of their unit response fields, this information is transformed differently in their output projections to the eye and head controllers.
authors.affiliation: Centre for Vision Research, York University, Toronto, ON, Canada.
authors.forename: Jachin A
authors.initials: JA
authors.lastname: Monteon
authors.forename: Hongying
authors.initials: H
authors.lastname: Wang
authors.forename: Julio
authors.initials: J
authors.lastname: Martinez-Trujillo
authors.forename: J Douglas
authors.initials: JD
authors.lastname: Crawford
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D005403:Fixation, Ocular; D019416:Head Movements; D008253:Macaca mulatta; D017397:Prefrontal Cortex / Q000502:physiology*; D012438:Saccades; D013477:Superior Colliculi / Q000502:physiology; D014794:Visual Fields