Abstract
Cellular responses to restricted light patterns (circular spots or vertical slits, 0.5–3.0 degrees in diameter) were studied in the anterior part of middle suprasylvian gyrus of cats anesthetized with chloralose. “On”, “off”, or “on-off”, phasic responses were observed over almost the entire visual field when stimulus intensities were two or more log units brighter than the background. When near-threshold stimuli were employed, restricted receptive fields (3–30 degrees in diameter) were located near the center of the visual field. The most extensive receptive field mapping was done near the horizontal meridian and the type of response often changed as the stimulus was moved to different parts of the field. Cells were influenced by both eyes and summation was observed during binocular stimulation. Many of the cells also responded to auditory click stimuli. After surgical ablation or undercutting of ipsilateral visual cortical areas and section of the corpus callosum, cells rarely responded to restricted light stimuli although diffuse light stimuli were still effective. Transient depression of visual cortex by the application of KCl also eliminated cell responses to restricted spots of light; responses returned with recovery of the depressed cortical areas. The present data indicate that neurons in this association area respond to restricted visual stimuli in a specific manner, and this sensory-specific visual input is dependent upon participation of visual cortex. It is suggested that this cortical locus plays a role in complex sensory mechanisms involving intermodality, sensory-specific interactions.
Published Version
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