Response to the length of moving visual stimuli of the brisk classes of ganglion cells in the cat retina.

Abstract

Response histograms were collected for brisk-sustained and brisk-transient ganglion cells in the cat retina as narrow bars were moved backwards and forwards across their receptive fields. When a bar of fixed length was moved across the centre of the receptive field with contrast proportional to velocity, a constant response was obtained as long as the centre of the receptive field was crossed within the summation time. However, if the length of the bar was such that it extended beyond the centre, then there was a small but steady increase in surround antagonism for an increase in velocity. The same response was produced by a brief whole-field flash as by an extended bar moving across the receptive field at high velocity if both stimulus conditions delivered the same energy uniformly across the receptive field. With brisk-sustained cells it was observed, for small bar lengths, that bar length and contrast could be exchanged to give a constant response, even when there was considerable non-linearity in the over-all stimulus-response relationship. Thus conditions that resulted in constant stimulus flux produced a constant response. This property was seen at both high and low velocities for the majority of brisk-sustained units. The stimulus-response relationship had a greater range of linearity at high velocities than at low velocities. From similar experiments with brisk-transient cells it was observed that bar length and contrast could only be exchanged to give a constant response at high velocities. At low velocities there was considerable non-linearity: there appeared to be saturation of the response from local regions and it was necessary to extend the bar outside such a region to obtain an increase in response. At lower velocities, despite the changes seen in length-response curves under different conditions of contrast and velocity, the degree of surround antagonism remained constant for a given cell. Further, both brisk-sustained and brisk-transient cells showed the same degree of surround antagonism.

Directional asymmetries in the length‐response profiles of cells in the feline dorsal lateral geniculate nucleus.

“…The biases seen in the present study of feline dLGN cells were found in X and Y cells, and cells exhibiting such biases did not appear to differ in any other respect from those with no bias. Although previous reports have not identified directional biases in feline retinal ganglion cells, only a very small number of studies have used similar stimulus protocols to those used in the present study (Rodieck & Stone, 1965;Lee & Willshaw, 1978;Cleland, Harding & Tulanay-Keesey, 1983a). Given that these previous studies primarily addressed other issues, it would appear premature to disregard the possibility that such biases might occur in the retina.…”

The Suppressive Field of Neurons in Lateral Geniculate Nucleus

“…The possible sources include the following: (1) mechanisms of suppression or gain control operating in retina (Cleland et al, 1983b; Responses were aligned so that maximum receptive field response is centered on 0°. Kaplan et al, 1987;Sclar, 1987;Cheng et al, 1995;Girardin et al, 2002;Nolt et al, 2004); (2) inhibitory circuitry in thalamus (Hubel and Wiesel, 1961;McIlwain and Creutzfeldt, 1967;Singer and Creutzfeldt, 1970;Levick et al, 1972;Cleland et al, 1983b;Cleland and Lee, 1985;Sherman and Koch, 1986;Kaplan et al, 1987;Funke and Eysel, 1998); and (3) negative feedback from visual cortex (Ahlsén and Lindström, 1983;Sherman and Koch, 1986;Murphy and Sillito, 1987;Sillito et al, 1993;Cudeiro and Sillito, 1996;Sillito and Jones, 2002;Webb et al, 2002;Worgotter et al, 2002;Alitto and Usrey, 2003).…”

Function of the Y optic nerve fibres in the cat: do they contribute to acuity and ability to discriminate fast motion?

“…The luminance of the spot without filters was 100 cd/M2 and this was reduced by interposing suitable neutral density filters. Contrast was defined as 'luminance of spot above background/luminance of background' (Cleland, Harding & Tulunay-Keesey, 1983). The luminances of spot and background were monitored regularly.…”