Goldfish ganglion cells with unusual receptive field properties.

Goldfish retinal ganglion cells with unusual response properties are described. Each cell was classified as either Y-like or W-like, based upon its responses to sinusoidally modulated contrast-reversal gratings presented at various positions across the cell's receptive field. The unusual responses of the cells (which distinguish them from typical Y-like and W-like cells) occurred when sinusoidal gratings were drifted across the receptive field at a constant temporal rate. These cells responded at double the stimulus temporal rate to low-spatial-frequency gratings; a Fourier decomposition of the response revealed a large second harmonic component. However, to high-spatial-frequency stimuli, the response modulated at the temporal frequency of the stimulus; the Fourier fundamental component dominated the response. To examine the underlying receptive field mechanisms of these cells, each cell's response was analyzed using several different response measures. The results suggest that the receptive field properties of these unusual cells differ from the typical center/surround organization and confirm recent findings that the receptive fields of goldfish ganglion cells consist of inhomogeneities and subareas.