The Journal of Neuroscience, March 1, 2001, 21(5):1710-1719
Specific Roles of NMDA and AMPA Receptors in
Direction-Selective and Spatial Phase-Selective Responses in Visual
Cortex
Casto
Rivadulla,
Jitendra
Sharma, and
Mriganka
Sur
Department of Brain and Cognitive Sciences, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139
Cells in the superficial layers of primary visual cortex (area 17)
are distinguished by feedforward input from thalamic-recipient layers
and by massive recurrent excitatory connections between neighboring
cells. The connections use glutamate as transmitter, and the
postsynaptic cells contain both NMDA and AMPA receptors. The possible
role of these receptor types in generating emergent responses of
neurons in the superficial cortical layers is unknown. Here, we show
that NMDA and AMPA receptors are both involved in the generation of
direction-selective responses in layer 2/3 cells of area 17 in cats.
NMDA receptors contribute prominently to responses in the preferred
direction, and their contribution to responses in the nonpreferred
direction is reduced significantly by GABAergic inhibition. AMPA
receptors decrease spatial phase-selective simple cell responses and
generate phase-invariant complex cell responses.
Key words:
cat primary visual cortex; glutamate receptors; cortical
networks; emergent responses; feedforward connections; recurrent
connections
Copyright © 2001 Society for Neuroscience 0270-6474/01/2151710-10$05.00/0
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