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Experience-dependent regulation of functional maps & protein expression in visual cortex

Jaffer, Sajjida 2009. Experience-dependent regulation of functional maps & protein expression in visual cortex. PhD Thesis, Cardiff University.

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Despite great progress in understanding of how experience modifies cortical circuitry in primary visual cortex (VI), the underlying physiological and molecular mechanisms still remain to be understood fully. Although some of the molecules associated with the critical period for ocular dominance plasticity in cats have been examined, the role of downstream signalling molecules that form pathways with receptor subunits has received scant attention. The present study demonstrates using optical imaging of intrinsic signals that sensory experience is not required for initial establishment of ocular dominance column layout and iso-orientation domains but is required for maintenance of these properties its absence leads to their eventual breakdown. Animals were sacrificed and VI was removed and homogenised, followed by immunoblotting for quantification of protein expression. The immunoblotting findings point to a set of proteins (including NR2A, PSD-95, aCaMKQ, NR2B and GABAAala) that are regulated developmentally and the effects of dark-rearing indicate that sensory activity regulates mechanisms associated with both excitatory (NR2A and NR2B) and inhibitory (GABAAala) transmission and synaptogenesis (synaptogenesis) so as to maintain a homeostatic balance. Pattern or form information is necessary in both eyes to maintain normal maps in both eyes while differences in illumination between two eyes did not affect ocular dominance and orientation maps in normally reared or in dark-reared cats subsequently exposed to light. Monocular deprivation (MD) for 2 days and 7 days resulted in similar depression of deprived eye responses. In contrast, potentiation of non-deprived eye responses was almost double in magnitude after 7 days compared to 2 days of MD. The immunoblotting findings demonstrate that MD regulates signalling molecules (PSD-95, aCaMKH and synGAP) downstream of NMD A receptors and GluRl subunit it appears that different mechanisms are activated depending on the nature of sensory experience.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > Q Science (General)
ISBN: 9781303217708
Date of First Compliant Deposit: 30 March 2016
Last Modified: 19 Mar 2016 23:31

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