Complex-Cell Responses Derived from Center-Surround Inputs: The Surprising Power of Intradendritic Computation

Part of Advances in Neural Information Processing Systems 9 (NIPS 1996)

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Bartlett Mel, Daniel Ruderman, Kevin Archie


Biophysical modeling studies have previously shown that cortical pyramidal cells driven by strong NMDA-type synaptic currents and/or containing dendritic voltage-dependent Ca++ or Na+ chan(cid:173) nels, respond more strongly when synapses are activated in several spatially clustered groups of optimal size-in comparison to the same number of synapses activated diffusely about the dendritic arbor [8]- The nonlinear intradendritic interactions giving rise to this "cluster sensitivity" property are akin to a layer of virtual non(cid:173) linear "hidden units" in the dendrites, with implications for the cel(cid:173) lular basis of learning and memory [7, 6], and for certain classes of nonlinear sensory processing [8]- In the present study, we show that a single neuron, with access only to excitatory inputs from unori(cid:173) ented ON- and OFF-center cells in the LGN, exhibits the principal nonlinear response properties of a "complex" cell in primary visual cortex, namely orientation tuning coupled with translation invari(cid:173) ance and contrast insensitivity_ We conjecture that this type of intradendritic processing could explain how complex cell responses can persist in the absence of oriented simple cell input [13]-


B. W. Mel, D. L. Ruderman and K. A. Archie