Detection and discrimination of relative spatial phase by V1 neurons. Academic Article uri icon

Overview

abstract

  • Edge-like and line-like features result from spatial phase congruence, the local phase agreement between harmonic components of a spatial waveform. Psychophysical observations and models of early visual processing suggest that human visual feature detectors are specialized for edge-like and line-like phase congruence. To test whether primary visual cortex (V1) neurons account for such specificity, we made tetrode recordings in anesthetized macaque monkeys. Stimuli were drifting equal-energy compound gratings composed of four sinusoidal components. Eight congruence phases (one-dimensional features) were tested, including line-like and edge-like waveforms. Many of the 137 single V1 neurons (recorded at 45 sites) could reliably signal phase congruence by any of several response measures. Across neurons, the preferred spatial feature had only a modest bias for line-like waveforms. Information-theoretic analysis showed that congruence phase was temporally encoded in the frequency band present in the stimuli. The most sensitive neurons had feature discrimination thresholds that approached psychophysical levels, but typical neurons were substantially less sensitive. In single V1 neurons, feature discrimination exhibited various dependences on the congruence phase of the reference waveform. Simple cells were over-represented among the most sensitive neurons and on average carried twice as much feature information as complex cells. However, the distribution of the indices of optimal tuning and discrimination of relative phase was indistinguishable in simple and complex cells. Our results suggest that phase-sensitive pooling of responses is required to account for human psychophysical performance, although variation in feature selectivity among nearby neurons is considerable.

publication date

  • July 15, 2002

Research

keywords

  • Discrimination, Psychological
  • Form Perception
  • Neurons
  • Space Perception
  • Visual Cortex

Identity

PubMed Central ID

  • PMC6757932

Scopus Document Identifier

  • 0037101625

Digital Object Identifier (DOI)

  • 10.1523/JNEUROSCI.22-14-06129.2002

PubMed ID

  • 12122074

Additional Document Info

volume

  • 22

issue

  • 14