Early cortical orientation selectivity: how fast inhibition decodes the order of spike latencies

J Comput Neurosci. Nov-Dec 2003;15(3):357-65. doi: 10.1023/a:1027420012134.

Abstract

Following a flashed stimulus, I show that a simple neurophysiological mechanism in the primary visual system can generate orientation selectivity based on the first incoming spikes. A biological model of the lateral geniculate nucleus generates an asynchronous wave of spikes, with the most strongly activated neurons firing first. Geniculate activation leads to both the direct excitation of a cortical pyramidal cell and disynaptic feed-forward inhibition. The mechanism provides automatic gain control, so the cortical neurons respond over a wide range of stimulus contrasts. It also demonstrates the biological plausibility of a new computationally efficient neural code: latency rank order coding.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Contrast Sensitivity
  • Excitatory Postsynaptic Potentials
  • Geniculate Bodies / anatomy & histology
  • Geniculate Bodies / physiology
  • Humans
  • Models, Biological
  • Neural Inhibition / physiology*
  • Neurons / physiology*
  • Orientation
  • Photic Stimulation
  • Reaction Time / physiology*
  • Time Factors
  • Visual Cortex / cytology
  • Visual Cortex / physiology*
  • Visual Pathways / physiology