Friday, September 19, 2008

Spine turnover and Cortical remapping

In the current issue of Nature Neuroscience, a paper by T. Heck et al, described the dynamics of  dendritic spine turnover and the role this plays the in the restructuring of interneuronal connections following  injury and altered sensory input. In the experiment, retinal lesions made to mice led to deafferented zones in the lesion projection site of  the visual cortex. These zones were observed to undergo increased spine turnover using two-photon microscopy. The rate of turnover, about 3.5x increase, which thought to be related the functional reorganization to stimulation of  retinal areas surrounding the lesion site. To test this idea complete retinal lesion were made to both eyes to eliminate all retinal input. In this condition, there was no significant increase in turnover rate of the visual cortex compared to control animals. 
Furthermore, in animals with with a single lesion, it was found that the turnover rate led to a replacement of ~90% of spines in the affected cortical regions. Also, these spines were  more likely to be stabilized for the duration of the experiment, lending additional support for their role in functional reorganization. 
These data suggest that spine turnover plays an important role in functional reorganization of cortex due to sensory stimulation.

Link to Nature Neuroscience  article

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