title: Spatial properties of X and Y cells in the lateral geniculate nucleus of the cat and conduction veolcities of their inputs.
abstract: Visual neurons in the lateral geniculate nucleus (LGN) of the cat may be separated into distinct X and Y classes based on a test of the linearity of spatial summation. Y cells produce nonlinear responses especially when the visual stimulus is a fine spatial grating. X cells exhibit mainly linear summation properties. X cells respond mainly at the fundamental modulation frequency of a contrast reversal grating while Y cells respond at the fundamental and at the second harmonic of the modulation frequency. The spatial resolution of X cells' fundamental responses and Y cells' second harmonic responses is about the same, and both are two to eight times higher than the spatial resolution of the Y cells' fundamental response. The conduction velocity of the Y optic tract afferents is greater than that of the velocity of the X afferents. However, the LGN latencies of the responses of the two classes of cells to optic chiasm stimulation overlap considerably.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D002415:Cats; D005071:Evoked Potentials; D005829:Geniculate Bodies / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology; D009431:Neural Conduction; D009433:Neural Inhibition; D009474:Neurons / Q000145:classification / Q000502:physiology; D009900:Optic Nerve / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology