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SUMMARY:Visual Cortical Placticity - Mark Hübener Max Planck Institute of
  Neurobiology\, Martinsried\, Germany
DTSTART:20090401T084500Z
DTEND:20090401T093000Z
UID:TALK17647@talks.cam.ac.uk
CONTACT:Anna Di Pietro
DESCRIPTION:Altered sensory input can change response properties in the vi
 sual cortex.  How this is implemented at the level of individual synapses 
 is not well understood. In this study we explore whether changes of neuron
 al response properties induced by monocular deprivation (MD) correlate wit
 h alterations of dendritic spines on pyramidal neurons in the visual corte
 x of adult mice.\nTo address this question\, we combined intrinsic signal 
 imaging and two-photon microscopy in mice implanted with cranial windows. 
 This approach allowed us to monitor functional changes of eye-representati
 on in the binocular part of the visual cortex\, as well as to image repeat
 edly the apical dendrites of GFP-labelled neurons before\, during and afte
 r MD. We found that a brief period of MD robustly altered the balance of d
 endritic spine turnover in layer 5 neurons in binocular visual cortex. Mor
 e spines were added during MD than under baseline conditions. In contrast\
 , the rate of spine elimination did not change during MD\, leading to an i
 ncreased spine density. Restoring binocular vision returned spine dynamics
  to baseline levels\, but absolute spine density remained persistently ele
 vated. Importantly\, spine addition did not increase again when the same e
 ye was closed for a second time. This absence of structural plasticity aft
 er a second MD episode contrast with a robust and even faster change of ey
 e-specific responses after repeated MD. Thus\, dendritic spines added duri
 ng the first monocular deprivation experience may provide a structural bas
 is for subsequent functional shifts. These results provide a strong link b
 etween functional plasticity and specific synaptic rearrangements\, reveal
 ing a mechanism of how prior experiences could be stored in cortical circu
 its. \n
LOCATION:Cripps Court\, Magdalene College
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