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Cerebral Cortex Advance Access published online on March 28, 2008
Cerebral Cortex, doi:10.1093/cercor/bhn038
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© 2008 The Authors
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Cortical Dynamics Subserving Visual Apparent Motion

Bashir Ahmed, Akitoshi Hanazawa, Calle Undeman, David Eriksson, Sonata Valentiniene and Per E. Roland

Brain Research, Department of Neuroscience, Karolinska Institute, Retzius vaeg 8, S17177 Solna, Sweden

Address correspondence to Bashir Ahmed, PhD, Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK. Email: bashir.ahmed{at}dpag.ox.ac.uk.

Motion can be perceived when static images are successively presented with a spatial shift. This type of motion is an illusion and is termed apparent motion (AM). Here we show, with a voltage sensitive dye applied to the visual cortex of the ferret, that presentation of a sequence of stationary, short duration, stimuli which are perceived to produce AM are, initially, mapped in areas 17 and 18 as separate stationary representations. But time locked to the offset of the 1st stimulus, a sequence of signals are elicited. First, an activation traverses cortical areas 19 and 21 in the direction of AM. Simultaneously, a motion dependent feedback signal from these areas activates neurons between areas 19/21 and areas 17/18. Finally, an activation is recorded, traveling always from the representation of the 1st to the representation of the next or succeeding stimuli. This activation elicits spikes from neurons situated between these stimulus representations in areas 17/18. This sequence forms a physiological mechanism of motion computation which could bind populations of neurons in the visual areas to interpret motion out of stationary stimuli.

Key Words: dendritic depolarization • neuron communication dynamics • visual cortex • visual motion • voltage sensitive dye


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