SPATIOTEMPORAL IMPULSE-RESPONSE AND CORTICAL MAGNIFICATION

According to a model of the spatiotemporal weighting function (Manahil ov, V. Spatiotemporal visual response at suprathreshold stimuli. Visio n Research, 1995, 35, 227-237; and Triphasic temporal impulse response s and Mach bands in time. Vision Research, 38, 447-458) the waveform o f the temporal-impulse response and the cortical spread of the spatial -impulse response should not depend on the retinal site of stimulation . To verify these model predictions, the spatiotemporal responses to b rief near-threshold lines presented in the fovea and the near retinal periphery were studied, The effect of an inducing stimulus on the thre shold for pattern detection of a test stimulus was measured, assuming that the pattern-detection threshold was determined by the test peak r esponse. The spatial spread of the line response expressed in visual-f ield units was increased with eccentricity. The temporal-impulse respo nses to foveal and peripheral stimuli were similar. The model of the w eighting function was used to evaluate the relative magnification fact or for the retinal location tested. The calculated cortical spatial-im pulse responses did not depend on the stimulation site. The data obtai ned are in line with the cortical magnification theory of peripheral v ision. (C) 1998 Elsevier Science Ltd. All rights reserved.