التفاصيل البيبلوغرافية
| العنوان: |
How Can a Patient Blind to Radial Motion Discriminate Shifts in the Center-of-Motion? |
| المؤلفون: |
Scott A. Beardsley, Lucia M. Vaina |
| المصدر: |
Journal of Computational Neuroscience; Jan2005, Vol. 18 Issue 1, p55-66, 12p |
| مصطلحات موضوعية: |
CEREBROVASCULAR disease patients, PHOTORECEPTORS, EYE, SENSE organs |
| مستخلص: |
Abstract Within biologically constrained models of heading and complex motion processing, localization of the center-of-motion (COM) is typically an implicit property arising from the precise computation of radial motion direction associated with an observers forward self-motion. In the work presented here we report psychophysical data from a motion-impaired stroke patient, GZ, whose pattern of visual motion deficits is inconsistent with this view. We show that while GZ is able to discriminate direction in circular motions she is unable to discriminate direction in radial motion patterns. GZs inability to discriminate radial motion is in stark contrast with her ability to localize the COM in such stimuli and suggests that recovery of the COM does not necessarily require an explicit representation of radial motion direction. We propose that this dichotomy can be explained by a circular template mechanism that minimizes a global motion error relative to the visual motion input, and we demonstrate that a sparse population of such templates is computationally sufficient to account for human psychophysical performance in general and in particular, explains GZs performance. Recent re-analysis of the predicted receptive field structures in several existing heading models provides additional support for this type of circular template mechanism and suggests the human visual system may have available circular motion mechanisms for heading estimation. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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