Responses of macaque ganglion cells to the relative phase of heterochromatically modulated lights. J Physiol

Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, West Germany.
The Journal of Physiology (Impact Factor: 5.04). 01/1993; 458(1):191-221. DOI: 10.1113/jphysiol.1992.sp019413
Source: PubMed


1. We measured the response of macaque ganglion cells to sinusoidally modulated red and green lights as the relative phase, theta, of the lights was varied. 2. At low frequencies, red-green ganglion cells of the parvocellular (PC-) pathway with opponent inputs from middle-wavelength sensitive (M-) and long-wavelength sensitive (L-) cones were minimally sensitive to luminance modulation (theta = 0 deg) and maximally sensitive to chromatic modulation (theta = 180 deg). With increasing frequency, the phase, theta, of minimal amplitude gradually changed, in opposite directions for cells with M- and L-cone centres. 3. At high frequencies (at and above 20 Hz), phasic cells of the magnocellular (MC-) pathway were maximally responsive when theta approximately 0 deg and minimally responsive when theta approximately 180 deg, as expected from an achromatic mechanism. At lower frequencies, the phase of minimal response shifted, for both on- and off-centre cells, to values of theta intermediate between 0 and 180 deg. This phase asymmetry was absent if the centre alone was stimulated with a small field. 4. For PC-pathway cells, it was possible to provide an account of response phase as a function of theta, using a model involving three parameters; phases of the L- and M-cone mechanisms and a L/M cone weighting term. For red-green cells, the phase parameters were monotonically related to temporal frequency and revealed a centre-surround phase difference. The phase difference was linear with a slope of 1-3 deg Hz-1. If this represents a latency difference, it would be 3-8 ms. Otherwise, temporal properties of the M- and L-cones appeared similar if not identical. By addition of a scaling term, the model could be extended to give an adequate account of the amplitude of responses. 5. We were able to activate selectively the surrounds of cells with short-wavelength (S-) cone input to their centres, and so were able to assess L/M cone weighting to the surround. M- and L-cone inputs added linearly for most cells. On average, the weighting corresponded to the Judd modification of the luminosity function although there was considerable inter-cell variability. 6. To account for results from MC-pathway cells, it was necessary to postulate a cone-opponent, chromatic input to their surrounds. We developed a receptive field model with linear summation of M- and L-cones to centre and surround, and with an additional M,L-cone opponent input to the surround.(ABSTRACT TRUNCATED AT 400 WORDS)

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    Psychology and Neuroscience 12/2013; 6(2):213-218. DOI:10.3922/j.psns.2013.2.09
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    • "Thus, there is imbalance in spectral inputs to centre and surround, allowing opponent colour signals to be transmitted to the brain without evolution of new colour-selective pathways. Consistent with this hypothesis, there is broad agreement that the majority of PC pathway cells show centre–surround organization, and that red–green opponency can arise from centre–surround interaction (Dreher et al. 1976; Derrington et al. 1984; Kaplan & Shapley, 1986; Smith et al. 1992; Lankheet et al. 1998; Kilavik et al. 2003; Blessing et al. 2004; Diller et al. 2004; Solomon et al. 2005; Buzás et al. 2006; Crook et al. 2011). By contrast, according to the original 'two channel' model for chromatic signal transmission, chromatic signals are carried by specific populations of cells showing ('type II') opposing spectral inputs to large and overlapping receptive field regions (Wiesel & Hubel, 1966; Dreher et al. 1976; Rodieck, 1991; Calkins & Sterling, 1999; Conway et al. 2010). "
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    • "Additional tests, e.g. measuring responses to heterochromatically modulated lights (Smith et al. 1992), were employed in cases when identification was difficult. PC cells can generally be identified by their tonic responses and spectral opponency, and MC cells by their phasic responses and lack of spectral opponency. "
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