Cooperative and competitive spatial interactions in motion integration.

JEAN LORENCEAU, LAURE ZAGO
Vis. Neurosci.. 1999-07-01; 16(04):
DOI: 10.1017/s0952523899164149

PubMed
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1. Vis Neurosci. 1999 Jul-Aug;16(4):755-70.

Cooperative and competitive spatial interactions in motion integration.

Lorenceau J(1), Zago L.

Author information:
(1)Laboratoire de Physiologie de la Perception et de l’Action, CNRS, Collège de
France, Paris.

Recovering the velocity of objects moving in the visual field requires both the
integration and segmentation of local neuronal responses elicited by moving
stimuli in primary visual cortex. Herein, we investigate the effects of the
contrast, density, spatial proximity, spatial frequency, and spatial
configuration of component motions on these complementary processes. Measuring
the ability of human observers to discriminate the global direction of motion
displays composed of spatially distributed patches of drifting gratings whose
motion is locally ambiguous, we provide psychophysical evidence that linking
component motion across space is facilitated at low contrast and high patch
density. Furthermore, direction discrimination depends on the spatial frequency
of component gratings and is more accurate for spatial configurations that
contain « virtual » L junctions as compared to configurations composed of « virtual »
T junctions. We suggest that the conditions yielding global motion coherence can
be accounted for by the existence of anisotropic cooperative/competitive,
contrast-dependent, long-range interactions among oriented direction-selective
units. In addition, we bring evidence that motion segmentation processes rely
upon the processing of moving local spatial discontinuities. The results are
discussed in the light of recent psychophysical and physiological evidence that
long-range excitatory and inhibitory interactions within primary visual cortex
modulate perceptual linking.

PMID: 10431923 [Indexed for MEDLINE]


Auteurs Bordeaux Neurocampus