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Exp Brain Res. 2002 Feb;142(4):512-28. Epub 2001 Dec 21.

Ocular fixation and visual activity in the monkey lateral intraparietal area.

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1
Institut des Sciences Cognitives, CNRS UMR-5015, 67 boulevard Pinel, 69675 Bron, France.

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.

PMID:
11845247
DOI:
10.1007/s00221-001-0954-z
[Indexed for MEDLINE]
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