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Single‐cell electrophysiology in macaque inferior parietal lobule during visually guided reach
Author(s) -
Ramalingam Nirmala,
Heider Barbara,
Karnik Anushree P,
Siegel Ralph Mitchell
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a380
Subject(s) - macaque , stimulus (psychology) , neuroscience , fixation (population genetics) , electrophysiology , fixation point , inferior parietal lobule , psychology , communication , biology , computer science , computer vision , cognition , cognitive psychology , biochemistry , gene
Neural correlates of visually‐guided reaching behavior in area 7a of posterior parietal cortex in macaques were studied with single‐cell electrophysiological recordings during a stereotyped reaching task. The task involved reaching to an optic‐flow stimulus. Initially the monkey held his hand on a start pad and fixated a white square on a screen. The monkey continued to fixate when the 20° optic flow appeared. Upon the motion changing, the monkey reached to its center holding the touch for 1.5 seconds. The targets and the fixation point appeared in one of 9 possible locations. Variations of the task were done – different fixation and peripheral target locations, similar fixation and targets location. Visual neurons responded to various phases of the task – fixation onset, stimulus onset, stimulus change. Some of the neurons show sustained activity for the entire duration of the stimulus presentation, while some only show bursts of activity at the initial onset or change in motion. Also, some neurons changed their tuning characteristics depending on position (sustained activity for some positions and brief activity for others) and task variations (coarse‐tuning for fixation‐target at the same locations and fine‐tuning for center‐fixation, peripheral targets). Reach neurons responded when the monkey reaches and touches the target – with some activated by the reach behavior, few inhibited. Neurons were also modulated by the target position, stimulus type and task variations. Few neurons exhibited both visual and reach‐dependent activity. Those that combined the two were quite complex (e.g. visually‐excited, but partially‐reach‐inhibited). The results suggest that the 7a neurons possess a rich repertoire of visual and reach properties representing visually guided reach.