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Biomedical subjects

M Sloane

Publications and source records attributed to M Sloane.

7 recordsLinked to original sources

Selective adaptation of monocular and binocular neurons in human vision.

Psychophysical techniques were used to examine how subpopulations of visual neurons varying in their ocular dominance interacted in determining performance on a visual task. Using an asymmetric alternating adaptation of the left and right eyes, we manipulated the sensitivity of monocularly driven neurons while keeping the sensitivity of binocularly driven neurons constant. Relative threshold elevations were measured in the left eye, right eye, and both eyes of five observers following different ratios of alternating adaptation. It was found that whereas monocularly measured aftereffects varied monotonically as a function of the adaptation duration of the measured eye, the magnitude of the binocularly measured aftereffect remained constant regardless of how the adaptation was divided between the two eyes. This suggests that neurons differing in their ocular dominance pool their activity in determining sensitivity to a test target.

Adaptation, Physiological

The square-wave illusion and phase anisotropy of the human visual system.

A triangular-wave grating is perceived to fluctuate over time: at one moment it may appear veridical (ie triangular), at another it may more closely resemble a square-wave grating with rounded edges. In addition, the square-wave illusion itself is bistable, in that it sometimes appears to shift in phase by 180 deg. Experiments in which the phase and amplitude of the first three frequency components of the triangular-wave grating were independently varied showed that the square-wave illusion results from the relative phase of the frequency components. Adaptation to two frequency components in square-wave (sine) phase was found to reduce the illusion strength, and adaptation to triangular-wave (cosine) phase was found to increase the illusion strength. In addition, the square-wave adaptation effect spreads to nonadapted retinal areas. It is concluded that the square-wave illusion reflects a phase anisotropy in the human visual system that favors square-wave phase over other phase relations.

Eye Movements