Binocular interactions in the cat's dorsal lateral geniculate nucleus. I. Spatial-frequency analysis of responses of X, Y, and W cells to nondominant-eye stimulation

Abstract

1. X, Y, and W cells in the A and C layers of the cat's dorsal lateral geniculate nucleus (LGN) were tested for responses to stimulation of the nondominant eye. The main purpose was to determine the incidence of nondominant-eye excitation and inhibition among different classes of cells and to examine the spatial-frequency tuning of responses to the nondominant eye. 2. Of 198 cells that were tested with drifting sine-wave gratings presented to the nondominant eye, 109 (55%) showed statistically significant responses. Four types of responses were observed: an increase in the mean discharge rate (F0 excitation), a decrease in the mean discharge rate (F0 inhibition), an increased modulation at the fundamental frequency of the grating (F1 excitation), and a decreased modulation at the fundamental frequency of the grating (F1 inhibition). Overall, 29% of the cells responded with inhibition, 24% responded with excitation, and 2% showed both excitation and inhibition, depending upon the spatial frequency and/or the harmonic response component. The relative incidence of excitation and inhibition was similar for X, Y, and W cells, for cells with on-center and off-center receptive fields, for cells with different receptive-field eccentricities, and for cells in each LGN layer. In addition, within layers A and A1, responses were similar for cells at different distances from the laminar borders. 3. Spatial-frequency response functions indicated that cells could have band-pass or low-pass spatial-frequency tuning through the nondominant eye. Band-pass cells tended to be narrowly tuned (less than or equal to 1 octave), and low-pass cells responded to a broader range of spatial frequencies. These properties were similar for X, Y, and W cells. Spatial resolution tended to be low (less than or equal to 0.8 c/deg for most cells), although a few cells responded to the highest spatial frequency tested (5.4 c/deg). Likewise, optimal spatial frequency was low (less than or equal to 0.2 c/deg) for most cells. These properties were similar for X and Y cells, and there was a weak tendency for X and Y cells to have higher optimal spatial frequencies and spatial resolutions than W cells. 4. In terms of absolute change in activity, responses to drifting gratings were weak. However, cells that were inhibited generally showed 20-60% decreases in activity to the optimal spatial frequency, and cells that were excited generally showed 40-100% increases. Response amplitudes were similar for X, Y, and W cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Development and Plasticity in Sensory Thalamus and Cortex

“…Binocular inhibitory responses seem to arise from interneurons that receive input from one eye and then inhibit relay cell activity from the other eye (Alhsen et al, 1985). Our observations in the rodent are consistent with those made in the cat and monkey (Alhsen et al, 1985;Guido et al, 1989;Schroeder et al, 1990) and suggest that binocular inhibitory interactions are a fundamental (albeit ignored) feature of mammalian geniculate circuitry.…”

Binocular visual responses in cells of the rat dLGN

“…Coupled with this, however, there are much smaller responses driven by the ‘non‐dominant’ eye, whose fields appear to be in spatial register and include both inhibitory and excitatory components. Excitatory responses may be powerfully suppressed by local inhibition such that they can only be revealed by removal of the overlying inhibition by pharmacological means (Murphy & Sillito, 1989), although this is a matter of some debate (see Guido et al 1989). In the data reported here, while many cells respond well to stimulation of the contralateral eye and appear unresponsive to the ‘non‐dominant’ ipsilateral eye (as would be expected form the lateral positioning of the eyes in the skull), some single units respond equally well to stimulation of either eye, with receptive field organization similar for each eye.…”

Synaptic organization of thalamocortical axon collaterals in the perigeniculate nucleus and dorsal lateral geniculate nucleus

“…Geniculate neurons have been shown to be affected by stimulation of the nondominant eye, and these effects include inhibition, excitation, or a combination of inhibition and excitation (Pape and Eysel 1986;Xue et al, 1987;Guido et al, 1989;Murphy and Sillito, 1989;Tong et al, 1992;Wang et al, 1994;Zhou et al, 2003). These effects have also been recorded in the absence of cortical input, and application of a GABA antagonist reveals excitatory responses elicited from stimulation of the nondominant eye (Murphy and Sillito, 1989).…”