Visual latency of ganglion X- and Y-cells: a comparison with geniculate X- and Y-cells.
Visual response latencies and rise times of X and Y ganglion cells recorded in the optic tract of anaesthetized, paralyzed cats were measured during repeated stimulation with sinusoidal gratings. These measures were compared with visual latencies and rise times of X- and Y-cells in the dorsal lateral geniculate nucleus. Measurements were restricted to individual trials on which the instantaneous discharge rate exceeded a criterion amplitude defined in terms of the statistics of the baseline activity of each cell in order to screen out false alarm responses. The onset and peak latencies of ganglion Y-cells are about 10-15 msec shorter than those of ganglion X-cells at low spatial frequencies (less than 0.25 c/deg) but about 10-20 msec longer at higher spatial frequencies (greater than 0.75 c/deg/). The onset latencies of geniculate X- and Y-cells lag their ganglion counterparts by 10-20 msec. Despite a delay in onsets of geniculate responses, the peak latencies of geniculate and ganglion X-cells are similar, and peak latencies of geniculate Y-cells are even shorter than those of their ganglion inputs. The short latencies of the peak responses of geniculate Y-cells are related to their short response rise times. A functional consequence of the bursty, but fast responses of geniculate Y-cells may be to accelerate the processing of lower spatial frequencies by the retino-geniculate Y-cell pathway.
Sestokas
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AK
Department of Neurosurgery, University of Maryland School of Medicine, Baltimore 21201.
Lehmkuhle
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S
Kratz
K E
KE
D000200:Action Potentials; D000818:Animals; D002415:Cats; D005074:Evoked Potentials, Visual; D005829:Geniculate Bodies / Q000502:physiology*; D009431:Neural Conduction; D010364:Pattern Recognition, Visual / Q000502:physiology; D012160:Retina / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013997:Time Factors