Optical imaging of visually evoked responses in the middle temporal area after deactivation of primary visual cortex in adult primates

Proc Natl Acad Sci U S A. 2005 Apr 12;102(15):5594-9. doi: 10.1073/pnas.0501762102. Epub 2005 Apr 4.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aging / physiology*
  • Animals
  • Aotidae / physiology*
  • Diagnostic Imaging
  • Evoked Potentials, Visual / drug effects
  • Evoked Potentials, Visual / physiology*
  • Galago / physiology*
  • Muscimol / pharmacology
  • Superior Colliculi / drug effects
  • Superior Colliculi / physiology*
  • Visual Cortex / drug effects
  • Visual Cortex / physiology*
  • Visual Pathways / drug effects
  • Visual Pathways / physiology*

Substances

  • Muscimol