Abstract
Synchronization accompanied by ?-range oscillations is generated among visual neurons in a manner that depends on certain key features of visual stimulation. Based on the correlation between this activity and perception, it has been suggested that this phenomenon may be important for perceptual integration. However, the causal relationship between them has yet to be explained. Here we show evidence for a functional role of the oscillatory synchronized activities in frog's visual information processing. We performed behavioral tests and multi-electrode recordings from ganglion cells in the isolated retinas. An expanding dark spot, which emulates an approaching predator, generated synchronized oscillatory discharges among OFF-sustained ganglion cells (dimming detectors) and elicited escape response. Intraocular injection of pharmacological agents changed the escape rate to the stimulus. These behavioral changes were ascribed not to changes in discharge rate but to modulation of synchronized oscillations. Furthermore, the pharmacological agents did not affect the expanding dark spot-induced responses in retinal ganglion cells other than dimming detectors. Thus, we conclude that synchronized oscillations encode escape-related information in frogs. The escape rate of frogs and the strength of synchronized oscillations increased as stimulus size or continuity increased. For escape behavior, the size and/or continuity of an object may be perceptually integrated by synchronized oscillations.
Supported by Grant-in-Aid for Scientific Research (12053212, 17022014, 14710040, 17730424, 1610444) and NRV Project