title: Ocular fixation and visual activity in the monkey lateral intraparietal area.
abstract: The macaque lateral intraparietal area (LIP) has been implicated in visuospatial attention and saccade planning. Since area LIP also contains a representation of the central visual field, we investigated its possible role in fixation and foveal attention in a visual fixation task with gap (momentary disappearance of fixation point). In addition to the expected visual neurons ( n=119), two main categories were identified: (1) cells responding tonically both during the presence and momentary absence of the fixation stimulus( n=47); a subset of these neurons studied in a saccade task showed perisaccadic inhibition in half of the cases (14/27). The timing of this inhibition, however, is only loosely related to saccade timing; (2) cells responding mainly to the absence of the fixation stimulus, with either abrupt or gradual onset of activity during the gap ( n=62). During saccades, these neurons showed presaccadic buildup and/or postsaccadic activity, which was spatially tuned in about half of the tested cells (28/53). Ninety-one percent of the cells in the first category and 59% of the cells in the second category were located in the dorsal portion of area LIP (LIPd). These results are consistent with the hypothesis of an oculomotor-attentional network contributing to fixation engagement and disengagement in a subregion of LIP.
authors.affiliation: Institut des Sciences Cognitives, CNRS UMR-5015, 67 boulevard Pinel, 69675 Bron, France.
authors.forename: S
authors.initials: S
authors.lastname: Ben Hamed
authors.forename: J-R
authors.initials: JR
authors.lastname: Duhamel
mesh_terms: D000818:Animals; D005403:Fixation, Ocular / Q000502:physiology*; D008252:Macaca fascicularis; D008253:Macaca mulatta; D009474:Neurons / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D014792:Visual Acuity / Q000502:physiology*