title: Superior colliculus inactivation alters the weighted integration of visual stimuli.
abstract: The primate superior colliculus (SC) is important for the winner-take-all selection of targets for orienting movements. Such selection takes time, however, and the earliest motor responses typically are guided by a weighted vector average of the visual stimuli, before the winner-take-all selection of a single target. We tested whether SC activity plays a role in this initial stage of orienting by inactivating the SC in two macaques (Macaca mulatta) with local muscimol injections. After SC inactivation, initial orienting responses still followed a vector average, but the contribution of the visual stimulus inside the affected field was decreased, and the contribution of the stimulus outside the affected field was increased. These results demonstrate that the SC plays an important role in the weighted integration of visual signals for orienting, in addition to its role in the winner-take-all selection of the target.
authors.affiliation: Systems Neurobiology Laboratory, Salk Institute for Biological Studies, University of California, San Diego, La Jolla, California 92037, USA. snummela@salk.edu
authors.forename: Samuel U
authors.initials: SU
authors.lastname: Nummela
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Krauzlis
mesh_terms: D000818:Animals; D005133:Eye Movements / Q000502:physiology; D008253:Macaca mulatta; D008297:Male; D008845:Microinjections / Q000379:methods; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology; D009949:Orientation / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
chemical_list: D009118:Muscimol