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M J Keck

Publications and source records attributed to M J Keck.

5 recordsLinked to original sources
PubMed1978

Visual evoked response as a function of grating spatial frequency.

Transient visual evoked responses (VER's) to the appearance-disappearance of sinusoidal gratings have been investigated for a range of spatial frequencies. Contrary to the results of previous studies, the results show that the transient VER consists of a relatively simple waveform that is most easily characterized by the initial negative peak (N1) whose latency and amplitude vary with the contrast and spatial frequency of the grating. At spatial frequencies less than 3 cycles/degree (c/d) an additional short latency component appears in the response. This component is maximum at 1 to 2 c/d, saturates at low contrast, and is insensitive to the precise position of the grating on the retina. The results are related to the properties of transient and sustained channels assumed to exist in the human visual system.

Adult↗
PubMed1977

Recovery from adaptation to moving gratings.

Short-term adaptation to moving sinusoidal gratings results in a motion aftereffect which decays in time. The time decay of the motion aftereffect has been measured psychophysically, and it is found to depend on (i) the spontaneous recovery from the adapted state, and (ii) the contrast of the test grating. We have measured the decays for various test conditions. An extrapolation of the measurements allows us to obtain a decay which represents the time course of the spontaneous recovery of the direction-sensitive mechanisms.

Figural Aftereffect↗