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Contrasting forms of synaptic plasticity in monkey inferotemporal and primary visual cortices

Murayama, Yusuke1; Fujita, Ichiro1,2; Kato, Makoto1

Learning and Memory

ACTIVITY-DEPENDENT synaptic plasticity was examined in vivo in two cortical areas of the adult monkey visual system, the primary visual and inferotemporal cortex, the first and late cortical stages essential for object recognition. Discontinuous high-frequency electrical stimulation of intrinsic horizontal connections in layer 2/3 caused contrasting forms of synaptic plasticity in the two areas. In the inferotemporal cortex, long-term potentiation of extracellular field potentials in layer 2/3 was induced, whereas in the same pathway of V1, identical stimulation protocol elicited long-term depression. The results indicate that susceptibility to synaptic plasticity varies among cortical areas in the monkey brain.

1Department of Cognitive Neuroscience, Osaka University Medical School, Yamadaoka 2-2, Suita, Osaka 565, Japan

2Corresponding Author: Ichiro Fujita

ACKNOWLEDGEMENTS: We thank A. Fine, Y. Oda and T. Tsumoto for comments on earlier versions of the manuscript and E. Sugitani for technical assistance. Supported by Core Research for Evolutionary Science and Technology (JST) and by grants from the Uehara Memorial Foundation and the Inamori Foundation (IF). Y.M. was supported by the Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists.

Received 10 February 1997; accepted 22 February 1997

© Lippincott-Raven Publishers.