Connectionists: Propagation of gratings across primary visual cortex visualized with voltage-sensitive dye imaging

[dirk jancke]

Dear colleagues,

I would like to draw your attention to our recently published paper.

Moving gratings have been used almost half a century to study the visual 
cortex.
We show for the first time its retinotopic motion across the brain's 
surface in parallel to orientation maps.

Onat S, Nortmann N, Rekauzke S, König P, & Jancke D (2011). Independent 
encoding of grating motion across stationary feature maps in primary 
visual cortex visualized with voltage-sensitive dye imaging. Neuroimage 
55: 1763-1770.

http://dx.doi.org/10.1016/j.neuroimage.2011.01.004

The vizualization of such multiplexed activity patterns became possible 
by using optical imaging with voltage-sensive dye.

download movie
http://homepage.ruhr-uni-bochum.de/Dirk.Jancke/brain_multiplexing.html

Abstract:

In early visual cortex different stimulus parameters are represented in 
overlaid feature maps. Such functioning was extensively explored by the 
use of drifting gratings characterized by orientation, spatial–temporal 
frequency, and direction of motion. However surprisingly, the direct 
cortical visuotopic drift of the gratings' stripy pattern has never been 
detected simultaneously to these stationary feature maps. It therefore 
remains to be demonstrated how physical signals of grating motion across 
the cortex are represented independently of other parametric maps and 
thus, how multi-dimensional input is processed independently to enable 
effective read-out further downstream.
Taking advantage of the high spatial and temporal resolution of 
voltage-sensitive dye imaging, we here show the real-time encoding of 
position and orientation. By decomposing the cortical responses to 
drifting gratings we visualize the typical emergence of stationary 
orientation maps in which specific domains exhibited highest amplitudes. 
Simultaneously to these patchy maps, we demonstrate coherently 
propagating waves of activity that precisely matched the actual movement 
of the gratings in space and time, most dominantly for spatial 
frequencies lower than the preferred range. Thus, the primary visual 
cortex multiplexes information about retinotopic motion by additional 
temporal modulation of stationary orientation signals. These signals may 
be used to variably extract coarse-grained object motion and form 
information at higher visual processing stages.

Best regards,
Dirk


-- 
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Dr. Dirk Jancke
Bernstein Group for Computational Neuroscience
Institut für Neuroinformatik, NB 2/27
Ruhr-University Bochum
D-44780 Bochum
Germany

Fax: +49 (0)234-32-14209
Tel: +49 (0)234-32-29490/1(lab) -27845(office)


email: jancke at neurobiologie.rub.de
http://homepage.ruhr-uni-bochum.de/Dirk.Jancke
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