Distortion products in geniculate X-cells: a physiological basis for masking by spatially modulated gratings?
The responses of X-cells in cat lateral geniculate nucleus, to complex grating patterns moving across the receptive field, were recorded with microelectrodes. The patterns were multi-component gratings, composed by adding a low spatial-frequency sinusoidal "signal" to a high spatial frequency "mask" which was either unmodulated, contrast-modulated (AM) or quasi-frequency modulated (QFM) at the signal frequency. The response to AM and QFM gratings has a component at the same frequency as the response to the "signal". This low frequency component has the properties of a distortion product generated by a quadratic non-linearity in the LGN. These properties may account for the psychophysical masking which occurs between modulated high-spatial-frequency gratings and gratings of the modulation frequency [Henning, Hertz and Broadbent (1975) Vision Res. 15, 887-897].
Department of Physiological Sciences, Medical School, Newcastle upon Tyne, England.
A M
AM
Derrington
D000200:Action Potentials; D000818:Animals; D002415:Cats; D005556:Form Perception / Q000502:physiology*; D005829:Geniculate Bodies / Q000502:physiology*; D008433:Mathematics; D008959:Models, Neurological; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology*; D011601:Psychophysics