Single-unit responses to whole-field visual stimulation in the pretectum of Rana pipiens.


Visually responsive single units were recorded from the pretectal region that includes the large-celled nucleus lentiformis mesencephali (nLM) in the leopard frog, Rana pipiens. During monocular stimulation of the contralateral eye, 60 single units responding to movement of a large-field, random-dot pattern were quantitatively analyzed using horizontal and vertical directions at each of four pattern velocities (0.4-40 degrees/s). All units were spontaneously active, motion sensitive, and the majority showed 'on'-'off' responses. Several different response profiles were observed, including velocity-sensitive units with peak response at 10 degrees/s, most of which showed directional selectivity, and speed-sensitive units that showed increasing spike frequencies as pattern velocity increased, but little or no directional selectivity. About one-third of all unit analyzed were direction-selective, and 55% of those responded optimally to the temporal-to-nasal (T-N) direction of motion. T-N units were recorded primarily from an area that lies dorsolaterally between nLM and the optic tectum, in the 'peri-nLM' region. The pronounced monocular optokinetic nystagmus (OKN) response asymmetry that occurs in anurans appears to be reflected in the response profiles of the T-N direction selective units.


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@article{Li1996SingleunitRT, title={Single-unit responses to whole-field visual stimulation in the pretectum of Rana pipiens.}, author={Zhuo Li and Katherine V. Fite and Neil M. Montgomery and Sanwu Wang}, journal={Neuroscience letters}, year={1996}, volume={218 3}, pages={193-7} }