From:
Sukie Crandall
Date: 2008-04-01 17:25:58 UTC
Subject: [ferrethealth] abstract
To: fhl <ferrethealth@yahoogroups.com>
Cereb Cortex. 2008 Mar 28 [Epub ahead of print]
Cortical Dynamics Subserving Visual Apparent Motion.
Ahmed B, Hanazawa A, Undeman C, Eriksson D, Valentiniene S, Roland PE.
Brain Research, Department of Neuroscience, Karolinska Institute,
Retzius vaeg 8, S17177 Solna, Sweden.
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.
PMID: 18375528 [PubMed - as supplied by publisher]
Sukie (not a vet)
Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html
[Non-text portions of this message have been removed]
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