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This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 101/6/3100    most recent 91254.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Crowder, N. A. Articles by Ibbotson, M. R. PubMed PubMed Citation Articles by Crowder, N. A. Articles by Ibbotson, M. R.

Direction and Contrast Tuning of Macaque MSTd Neurons During Saccades

¹Visual Sciences Group and Australian Research Council Centre of Excellence in Vision Science, Australian National University, Canberra, Australian Capital Territory, Australia; ²Visual Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia; ³Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada; and ⁴Department of Neurobiology, Harvard Medical School, Boston, Massachusetts

Submitted 17 November 2008; accepted in final form 1 April 2009

Saccades are rapid eye movements that change the direction of gaze, although the full-field image motion associated with these movements is rarely perceived. The attenuation of visual perception during saccades is referred to as saccadic suppression. The mechanisms that produce saccadic suppression are not well understood. We recorded from neurons in the dorsal medial superior temporal area (MSTd) of alert macaque monkeys and compared the neural responses produced by the retinal slip associated with saccades (active motion) to responses evoked by identical motion presented during fixation (passive motion). We provide evidence for a neural correlate of saccadic suppression and expand on two contentious results from previous studies. First, we confirm the finding that some neurons in MSTd reverse their preferred direction during saccades. We quantify this effect by calculating changes in direction tuning index for a large cell population. Second, it has been noted that neural activity associated with saccades can arrive in the parietal cortex 30 ms earlier than activity produced by similar visual stimulation during fixation. This led to the question of whether the saccade-related responses were visual in origin or were motor signals arising from saccade-planning areas of the brain. By comparing the responses to saccades made over textured backgrounds of different contrasts, we provide strong evidence that saccade-related responses were visual in origin. Refinements of the possible models of saccadic suppression are discussed.