title: Middle temporal visual area microstimulation influences veridical judgments of motion direction.
abstract: Microstimulation of direction columns in the middle temporal visual area (MT, or V5) provides a powerful tool for probing the relationship between cortical physiology and visual motion perception. In the current study we obtained "veridical" reports of perceived motion from rhesus monkeys by permitting a continuous range of possible responses that mapped isomorphically onto a continuous range of possible motion directions. In contrast to previous studies, therefore, the animals were freed from experimenter-imposed "categories" that typify forced choice tasks. We report three new findings: (1) MT neurons with widely disparate preferred directions can cooperate to shape direction estimates, inconsistent with a pure "winner-take-all" read-out algorithm and consistent with a distributed coding scheme like vector averaging, whereas neurons with nearly opposite preferred directions seem to compete in a manner consistent with the winner-take-all hypothesis, (2) microstimulation can influence direction estimates even when paired with the most powerful motion stimuli available, and (3) microstimulation effects can be elicited when a manual response (instead of our standard oculomotor response) is used to communicate the perceptual report.
authors.affiliation: Howard Hughes Medical Institute and Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: M James
authors.initials: MJ
authors.lastname: Nichols
authors.forename: William T
authors.initials: WT
authors.lastname: Newsome
mesh_terms: D000465:Algorithms; D000818:Animals; D001931:Brain Mapping; D004558:Electric Stimulation / Q000379:methods; D005403:Fixation, Ocular / Q000502:physiology; D007600:Judgment / Q000502:physiology*; D008253:Macaca mulatta; D008839:Microelectrodes; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D015203:Reproducibility of Results; D012438:Saccades / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*