Experimental Brain Research

, Volume 79, Issue 3, pp 582–588

The effects of contrast on the linearity of spatial summation of simple cells in the cat's striate cortex

  • D. J. Tolhurst
  • A. F. Dean

DOI: 10.1007/BF00229326

Cite this article as:
Tolhurst, D.J. & Dean, A.F. Exp Brain Res (1990) 79: 582. doi:10.1007/BF00229326


Non-linearities of spatial summation were examined in simple cells in the cat's striate cortex. The degree of non-linearity was assessed from an examination of the waveforms of the responses to moving sinusoidal gratings and was quantified by a measure called relative modulation. Relative modulation was affected little by changes in contrast at either optimal or non-optimal spatial frequencies. The non-linearities of spatial summation exhibited by some simple cells are, therefore, essential. Those simple cells which exhibit linear spatial summation are no less linear at high stimulus contrasts. These results support a ‘push-pull’ model of simple cell receptive field organization in which ON and OFF centre l.g.n. input is combined both additively and subtractively.

Key words

Visual cortex Contrast Spatial summation Cat 

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • D. J. Tolhurst
    • 1
  • A. F. Dean
    • 1
  1. 1.Physiological LaboratoryCambridgeUK
  2. 2.Department of PathologyQueen Mary's Hospital, Green CollegeLondonUK

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