Visual Neuroscience

Research Articles

Visual latencies in areas V1 and V2 of the macaque monkey

L.G. Nowaka1, M.H.J. Munka1, P. Girarda1 and J. Bulliera1

a1 Cerveau et Vision, INSERM Unité 371, 18 avenue du Doyen Lepine, 69500 Bron/Lyon, France


Latencies to small flashing spots of light were measured in different layers of areas V1 and V2 in anesthetized and paralyzed macaque monkeys. The shortest latencies were found in layers 4Cα and 4B of area V1. Latencies in layer 4Cβ were on average 20 ms longer than those in 4Cα and 4B. The shortest latencies in area V2 were observed in the infragranular layers and they did not differ significantly from those found in the infragranular layers in V1. Similarly, latencies in the supragranular layers of V2 were not significantly different from those measured in the supragranular layers of V1. These results show that, in area V1, neurons of the magnocellular pathway are activated on average 20 ms earlier than those of the parvocellular pathway. Our data also suggest that much processing begins simultaneously in areas V1 and V2.

(Received June 23 1994)

(Accepted September 23 1994)


p1 Present address: Max Planck Institut für Hirnforschung, Postfach 71 06 62, 6000 Frankfurt/M. 71, Germany.


Reprint requests to: J. Bullier, Cerveau et Vision, INSERM Unité 371, 18 avenue du Doyen Lépine, 69500 Bron/Lyon, France.