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P.R. Martin, B.A. Szmajda, P. Buzas, T. FitzGibbon, E.M. Blessing; Spatial and Temporal Properties of Blue–Off Cells in the Lateral Geniculate Nucleus of the Marmoset . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5379.
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© ARVO (1962-2015); The Authors (2016-present)
To compare spatial and temporal tuning properties of blue–off, blue–on, and parvocellular (PC) cells in the lateral geniculate nucleus (LGN) of marmosets.
Extracellular single–unit recordings were made from blue–off cells (n=15) in the LGN of sufentanil anaesthetised marmosets (n=9). Stimuli were luminance modulated (yellow–black) or S–cone selective (S–cone contrast >60%, ML cone contrast <5%) drifting sinusoidal gratings of variable spatial and temporal frequency.
Blue–off cells respond to S–cone modulation in approximately opposite temporal phase to blue–on cells (mean phase difference: 162 deg). Regression of response phase on temporal frequency showed greater equivalent latency for blue–off (95.8 S.D. 33.8 ms, n=8) than PC cells (55.2 S.D. 7.9 ms, n=24). Receptive field center radius (rc) of blue–off cells (n=15) was larger than those of blue–on (n=36) or PC (n=87) cells (< 2 deg eccentricity, blue–off: mean 0.48 S.D. 0.34 deg; blue–on: 0.11 S.D. 0.04 deg; PC: 0.04 S.D. 0.02 deg; 2–20 deg, mean rc, blue–off: 0.96 S.D. 0.68 deg; blue–on: 0.38 S.D. 0.45 deg; PC: 0.08 S.D. 0.05 deg). Histological reconstruction of some electrode tracks showed all blue–off cells (4/4) recovered were in koniocellular layers.
The large receptive field size, sluggish temporal characteristic and location of blue–off cells are consistent with the idea that they form part of the third (koniocellular) retino–geniculo–cortical pathway.
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