December 2010
Volume 10, Issue 15
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OSA Fall Vision Meeting Abstract  |   December 2010
Circuitry and receptive field structure underlying ‘double duty’ performance by midget ganglion cells
Author Affiliations
  • Joanna D. Crook
    Department of Biological Structure, University of Washington, WA, USA
  • Dennis M. Dacey
    Department of Biological Structure, University of Washington, WA, USA
Journal of Vision December 2010, Vol.10, 5. doi:10.1167/10.15.5
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      Joanna D. Crook, Dennis M. Dacey; Circuitry and receptive field structure underlying ‘double duty’ performance by midget ganglion cells. Journal of Vision 2010;10(15):5. doi: 10.1167/10.15.5.

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Abstract

The potential for midget cells to do ‘double duty’ and encode chromatic and achromatic responses has long been recognized (DeValois, 1975, Wiesel and Hubel, 1966, Lennie et al., 1991) but not supported due to two outstanding problems. The midget cells achromatic sensitivity is poor (Derrington and Lennie, 1984, Kaplan and Shapley, 1986) and the number of ‘red-green’ chromatic cells outside the fovea is greater than expected suggesting the development of specialized circuitry for color coding (Lee, 2004). Here we record from central midget ganglion cells in the choroid-RPE attached in-vitro macaque retina and reexamine these issues. We characterized the midget cell receptive field with cone-specific stimuli. All midget cells displayed clear center-surround receptive field structure. Either one or both cone types contributed to the center; both cone types always contributed to the surround (n=60). Achromatic responses were elicited to stimuli restricted to the center while chromatic responses were highly dependent on broad stimuli that engaged center and surround. Varying the contrast of stimuli constrained to the receptive field center revealed high achromatic contrast sensitivity with gains greater than 2 (n=30). To test for cone-specific inhibitory circuits we blocked glycinergic and GABAergic inhibition and found that chromatic responses persisted unperturbed (n=48). In contrast, blocking ‘randomly wired’ horizontal cell feedback (Dacey et al., 1996), by increasing the retinas buffering capacity (Davenport, 2008), abolished opponent responses (n=14). Thus we find that the midget cells classic center and surround receptive field structure permits relay of both chromatic and achromatic signals with high contrast sensitivity and without recourse to specialized inhibitory circuits.

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Davenport, C. M., Detwiler, P. B., Dacey, D. M.(2008). Effects of pH buffering on horizontal and ganglion cell light responses in primate retina: evidence for the proton hypothesis of surround formation. Journal of Neuroscience, 28, 456–464. [CrossRef] [PubMed]
Derrington, A. M., Krauskopf, J., Lennie, P.(1984). Chromatic Mechanisms in Lateral Geniculate Nucleus of Macaque. Journal of Physiology, 357, 241–265. [CrossRef] [PubMed]
De Valois, R. L., De Valois, K. K.(1975). ‘Neural coding of color’. In Carterette, E. C., Friedman, M. P. (Eds.), Handbook of Perception, vol. V
Kaplan, E., Shapley, R. M.(1986). The primate retina contains two types of ganglion cells, with high and low contrast sensitivity. Proceedings of the National Academy of Sciences of the U.S.A., 83, 2755–2757. [CrossRef]
Lee, B. B.(2004). Paths to color in the retina. Clinical & Experimental Optometry, 87, 239–248. 96.
Lennie, P., Haake, P. W., Williams, D. R.(1991). Computational models of visual processing. Landy, M. S., Movshon, J. A. (Eds.), (pp. 71–82). The MIT Press.
Wiesel, T. N., Hubel, D. H.(1966). Spatial and chromatic interactions in the lateral geniculate body of the rhesus monkey. Journal of Neurophysiology, 29, 1115–1156.
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