A model for the estimate of local image velocity by cells in the visual cortex
Open Access
- 22 March 1990
- journal article
- research article
- Published by The Royal Society in Proceedings of the Royal Society of London. B. Biological Sciences
- Vol. 239 (1295) , 129-161
- https://doi.org/10.1098/rspb.1990.0012
Abstract
Some computational theories of motion perception assume that the first stage en route to this perception is the local estimate of image velocity. However, this assumption is not supported by data from the primary visual cortex. Its motion sensitive cells are not selective to velocity, but rather are directionally selective and tuned to spatio-temporal frequencies. Accordingly, physiologically based theories start with filters selective to oriented spatio-temporal frequencies. This paper shows that computational and physiological theories do not necessarily conflict, because such filters may, as a population, compute velocity locally. To prove this point, we show how to combine the outputs of a class of frequency tuned filters to detect local image velocity. Furthermore, we show that the combination of filters may simulate ‘Pattern’ cells in the middle temporal area (MT), whereas each filter simulates primary visual cortex cells. These simulations include three properties of the primary cortex. First, the spatio-temporal frequency tuning curves of the individual filters display approximate space-time separability. Secondly, their direction-of-motion tuning curves depend on the distribution of orientations of the components of the Fourier decomposition and speed of the stimulus. Thirdly, the filters show facilitation and suppression for responses to apparent motions in the preferred and null directions, respectively. It is suggested that the MT’s role is not to solve the aperture problem, but to estimate velocities from primary cortex information. The spatial integration that accounts for motion coherence may be postponed to a later cortical stage.This publication has 56 references indexed in Scilit:
- A parallel algorithm for real-time computation of optical flowNature, 1989
- Early vision and texture perceptionNature, 1988
- Nonlinear directionally selective subunits in complex cells of cat striate cortexJournal of Neurophysiology, 1987
- Direction specific masking and the analysis of motion in two dimensionsVision Research, 1987
- Spatial‐frequency characteristics of neurones of area 18 in the cat: dependence on the velocity of the visual stimulus.The Journal of Physiology, 1985
- Direction and orientation selectivity of neurons in visual area MT of the macaqueJournal of Neurophysiology, 1984
- Phenomenal coherence of moving visual patternsNature, 1982
- Connectionist Models and Their PropertiesCognitive Science, 1982
- Visual hyperacuity: spatiotemporal interpolation in human visionProceedings of the Royal Society of London. B. Biological Sciences, 1981
- Phi movement as a subtraction processVision Research, 1970