Response variability of marmoset parvocellular neurons

J. D. Victor, E. M. Blessing, J. D. Forte, P. Buzás, P. R. Martin

Research output: Contribution to journalArticle

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Abstract

This study concerns the properties of neurons carrying signals for colour vision in primates. We investigated the variability of responses of individual parvocellular lateral geniculate neurons of dichromatic and trichromatic marmosets to drifting sinusoidal luminance and chromatic gratings. Response variability was quantified by the cycle-to-cycle variation in Fourier components of the response. Averaged across the population, the variability at low contrasts was greater than predicted by a Poisson process, and at high contrasts the responses were approximately 40% more variable than responses at low contrasts. The contrast-dependent increase in variability was nevertheless below that expected from the increase in firing rate. Variability falls below the Poisson prediction at high contrast, and intrinsic variability of the spike train decreases as contrast increases. Thus, while deeply modulated responses in parvocellular cells have a larger absolute variability than weakly modulated ones, they have a more favourable signal: noise ratio than predicted by a Poisson process. Similar results were obtained from a small sample of magnocellular and koniocellular ('blue-on') neurons. For parvocellular neurons with pronounced colour opponency, chromatic responses were, on average, less variable (10-15%, p <0.01) than luminance responses of equal magnitude. Conversely, non-opponent parvocellular neurons showed the opposite tendency. This is consistent with a supra-additive noise source prior to combination of cone signals. In summary, though variability of parvocellular neurons is largely independent of the way in which they combine cone signals, the noise characteristics of retinal circuitry may augment specialization of parvocellular neurons to signal luminance or chromatic contrast.

Original languageEnglish
Pages (from-to)29-51
Number of pages23
JournalJournal of Physiology
Volume579
Issue number1
DOIs
Publication statusPublished - Feb 15 2007

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Callithrix
Neurons
Color
Noise
Color Vision
Primates
Population

ASJC Scopus subject areas

  • Physiology

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Victor, J. D., Blessing, E. M., Forte, J. D., Buzás, P., & Martin, P. R. (2007). Response variability of marmoset parvocellular neurons. Journal of Physiology, 579(1), 29-51. https://doi.org/10.1113/jphysiol.2006.122283

Response variability of marmoset parvocellular neurons. / Victor, J. D.; Blessing, E. M.; Forte, J. D.; Buzás, P.; Martin, P. R.

In: Journal of Physiology, Vol. 579, No. 1, 15.02.2007, p. 29-51.

Research output: Contribution to journalArticle

Victor, JD, Blessing, EM, Forte, JD, Buzás, P & Martin, PR 2007, 'Response variability of marmoset parvocellular neurons', Journal of Physiology, vol. 579, no. 1, pp. 29-51. https://doi.org/10.1113/jphysiol.2006.122283
Victor, J. D. ; Blessing, E. M. ; Forte, J. D. ; Buzás, P. ; Martin, P. R. / Response variability of marmoset parvocellular neurons. In: Journal of Physiology. 2007 ; Vol. 579, No. 1. pp. 29-51.
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