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Jan Churan, Stefan Dowiasch, Andre Kaminiarz, Frank Bremmer; Differential responses of neurons in the macaque Lateral Intraparietal area to voluntary and reflexive saccades. Journal of Vision 2017;17(10):1145. doi: 10.1167/17.10.1145.
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The macaque lateral intraparietal area (LIP) is known for its involvement in processing of saccadic eye movements (Barash et al. 1991) as well as higher cognitive concepts like attention (Bisley & Goldberg 2003), value (Sugrue et al. 2004) and numerosity (Roitman 2007). While its contribution to cognitive processes is being heavily investigated, some of its basic visuo-motor functions are not described yet. We investigated the responses of 96 single neurons from area LIP of one macaque monkey to different types of fast eye movements. The neurons were first tested using regular visually guided saccade and delayed saccade paradigms. Neurons that have shown a significant (p< 0.05) peri-saccadic response were further investigated using two other categories of fast eye movements. The first category were saccades interacting with smooth pursuit eye movements (SPEM) such as visually guided saccades to moving targets and catch-up saccades that are used to re-foveate a moving target during SPEM. The second category of eye movements were fast phases of the optokinetic nystagmus (OKN). We found huge differences between the responses to the two categories. While saccades in combination with SPEM revealed similar motor responses like regular visually guided saccades (significant visuo-motor responses were preserved in all neurons), none of the neurons responded significantly during the fast phases of the OKN. However, we found a modulation of activity in OKN that consisted of a significant post-saccadic inhibition in ~50% of the investigated neurons. The inhibition was regularly followed by a brief peak in activity which may be caused by a release from inhibition. We conclude that area LIP is not primarily concerned with generation of motor commands for fast eye movements but with goal directed interaction and target selection in the visual environment (Thomas & Pare 2007).
Meeting abstract presented at VSS 2017
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