Synaptic Zinc and Cortical Sensory Processing in the Laboratory Mouse
Date
2014-01-30
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Abstract
A growing body of evidence indicates that synaptic zinc plays an important role in regulating neocortical neurotransmission. The goal of this thesis was to further examine the pattern of the distribution of synaptic zinc in the mammalian cortex and how synaptic zinc mediates synaptic transmission to affect cortical function and the generation of behaviour.
The mouse visual cortex was used as a model system to observe the experience-dependent regulation of synaptic zinc levels. Histochemical analysis revealed that monocular deprivation dynamically altered the distribution of synaptic zinc in the deprived ocular domains of the visual cortex. Short (1 day) deprivation dramatically increased synaptic zinc density in layer IV of the deprived domains while long-term (3 months) deprivation elevated synaptic zinc levels in layers V and II/III. This result was similar to observations made in the visual cortex of cats and monkeys as well the barrel cortex of mice.
The relationship between synaptic zinc in the barrel cortex and the processing of vibrissal sensory input was examined by assessing barrel cortex-dependent behaviour in a transgenic mouse that does not have synaptic zinc (ZnT3 KO mouse). A novel behavioural test that measured barrel cortex-dependent texture discrimination was devised and used to assay mystacial vibrissae function in ZnT3 KO mice. It was observed that ZnT3 KO mice retained the ability to use vibrissal tactile information to discriminate between textures but the acuity of the vibrissal sensory system was greatly reduced. In vivo voltage-sensitive dye imaging revealed that stimulation-evoked activity in the barrel cortex of ZnT3 KO mice is altered.
Together, the results of this thesis suggest that synaptic zinc levels are dynamically modulated by sensory experience and that synaptic zinc contributes to the integration of sensory information within the primary sensory cortices.
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Neuroscience
Citation
Wu, H. P. (2014). Synaptic Zinc and Cortical Sensory Processing in the Laboratory Mouse (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27948