title: Optical imaging of visually evoked responses in the middle temporal area after deactivation of primary visual cortex in adult primates.
abstract: The middle temporal area (MT) is a visual area in primates with direct and indirect inputs from the primary visual cortex (V1), a role in visual motion perception, and a suggested role in "blindsight." When V1 is deactivated, some studies report continued activation of MT neurons, which has been attributed to an indirect pathway to MT from the superior colliculus. Here we used muscimol to deactivate V1 while optically imaging visually evoked activity in MT in two primates, owl monkeys and galagos, where MT is exposed on the brain surface. The partial loss of V1 inputs abolished all or nearly all evoked activity in the retinotopically matched part of MT. Low levels of activation that persisted in portions of MT that were unstimulated or retinotopically congruent with the blocked portion of V1 appeared to reflect the spread of activity from stimulated to unstimulated parts of MT. Thus, a significant pathway based on the superior colliculus was not demonstrated.
authors.affiliation: Department of Psychology, Vanderbilt University, Wilson Hall, 111 21st Avenue South, Nashville, TN 37203, USA.
authors.forename: Christine E
authors.initials: CE
authors.lastname: Collins
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Xu
authors.forename: Ilya
authors.initials: I
authors.lastname: Khaytin
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kaskan
authors.forename: Vivien A
authors.initials: VA
authors.lastname: Casagrande
authors.forename: Jon H
authors.initials: JH
authors.lastname: Kaas
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D016645:Aotidae / Q000502:physiology*; D003952:Diagnostic Imaging; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology*; D005701:Galago / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology*; D014793:Visual Cortex / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology*
chemical_list: D009118:Muscimol