The goal of this proposal is to elucidate the mechanisms of cortical structural plasticity by combining innovative in vivo imaging technology with classical visual manipulations. This integrative approach holds the potential to revolutionize our understanding of adaptive circuit modification, a fundamental aspect of brain function. Our previous findings show that while pyramidal neurons in layer 2/3 of adult visual cortex show little, if any, change in branch tip length over time, GABAergic non-pyramidal interneurons display significant dendritic branch tip remodelling driven by visual experience in an input and circuit-specific manner. The fact that structural plasticity of interneurons is continuous through adulthood raises the intriguing possibility that local remodelling of inhibitory connections may underlie adult cortical plasticity. Yet, how experience alters inhibitory circuitry is unclear, and how modifications to inhibitory and excitatory circuits are locally coordinated remains unaddressed. In the previous funding period we developed a method for labeling inhibitory synapses in vivo and simultaneously monitored inhibitory synapse and dendritic spine remodeling across the entire dendritic arbor of cortical layer 2/3 pyramidal neurons in vivo during normal and altered visual experience. We found that the rearrangements of inhibitory synapses and dendritic spines are locally clustered, mainly within 10 ?m of each other, and that this clustering is influenced by experience. In this proposal we seek to characterize with high temporal resolution the nature of the coordinated insertion and removal of excitatory synapses and neighboring inhibitory synapses in the neocortical circuit. To this purpose we will implement a newly developed three-color labeling system to independently and simultaneously monitor the formation and disappearance of dendritic spines along with appearance or removal of the post-synaptic density in these spines, and the appearance and removal of inhibitory synapses along the same dendrites. Using spectrally resolved two-photon microscopy we will 1) monitor the temporal sequence of inhibitory and excitatory synapse remodeling in vivo across the full dendritic arbor of L2/3 pyramidal neurons at short time intervals;2) monitor the effects of experience- dependent plasticity on coordination of inhibitory and excitatory synapse remodeling;3) examine the specificity of afferent inputs to coordinated excitatory/inhibitory synaptic pairs. Further, 4) we will develop and implement spectrally resolved multifocal multiphoton microscopy to further enhance imaging speed and allow interrogation of synaptic dynamics at even shorter time intervals.
It is thought that many neurodevelopmental disorders, including ones that effect visual perception, result from disruption of experience-dependent plasticity leading to deficits in synaptic connectivity, stabilization, or maturation. In this propsal we combine innovative in vivo imaging technology and molecular labeling methods with classical visual manipulations to elucidate how experience can lead to cortical structural plasticity. Characterizing the dynamic potential of cortical neurons, particularly interneurons, wil provide a baseline for future testing of molecules with therapeutic potential for promoting plasticity in the cerebral cortex that may be used to compensate for insults or deterioration at multiple levels of the visual pathway.
|Choi, Heejin; So, Peter T C (2014) Improving femtosecond laser pulse delivery through a hollow core photonic crystal fiber for temporally focused two-photon endomicroscopy. Sci Rep 4:6626|
|Cha, Jae Won; Singh, Vijay Raj; Kim, Ki Hean et al. (2014) Reassignment of scattered emission photons in multifocal multiphoton microscopy. Sci Rep 4:5153|
|Cha, Jae Won; Tzeranis, Dimitrios; Subramanian, Jaichandar et al. (2014) Spectral-resolved multifocal multiphoton microscopy with multianode photomultiplier tubes. Opt Express 22:21368-81|
|Chen, Jerry L; Nedivi, Elly (2013) Highly specific structural plasticity of inhibitory circuits in the adult neocortex. Neuroscientist 19:384-93|
|Chen, Jerry L; Villa, Katherine L; Cha, Jae Won et al. (2012) Clustered dynamics of inhibitory synapses and dendritic spines in the adult neocortex. Neuron 74:361-73|
|Chen, Jerry L; Lin, Walter C; Cha, Jae Won et al. (2011) Structural basis for the role of inhibition in facilitating adult brain plasticity. Nat Neurosci 14:587-94|
|Chen, Jerry L; Flanders, Genevieve H; Lee, Wei-Chung Allen et al. (2011) Inhibitory dendrite dynamics as a general feature of the adult cortical microcircuit. J Neurosci 31:12437-43|
|Cha, Jae Won; Ballesta, Jerome; So, Peter T C (2010) Shack-Hartmann wavefront-sensor-based adaptive optics system for multiphoton microscopy. J Biomed Opt 15:046022|
|Chen, Jerry L; Nedivi, Elly (2010) Neuronal structural remodeling: is it all about access? Curr Opin Neurobiol 20:557-62|
|Holtmaat, Anthony; Bonhoeffer, Tobias; Chow, David K et al. (2009) Long-term, high-resolution imaging in the mouse neocortex through a chronic cranial window. Nat Protoc 4:1128-44|
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