Cortical plasticity: structural and functional changes in cortical neurons and their connections
The cerebral cortex is one of the most complex structures, with an estimated 100 billion neurons connected with one another. One of the key features of the cortex that allows us to adapt our behavior in response to experience is its plasticity, i.e. the ability to reorganize and rewire structural and functional connections in response to changes in the environment. A great deal of progress has been made toward understanding cortical plasticity. This dissertation focuses on how distinct sensory stimuli induce structural and functional plasticity. First, using in vivo two photon imaging, we investigate the effect of two types of experience-dependent plasticity, motor learning and sensory deprivation, on structural plasticity of distinct cortical layer neurons. Our data reveal that neurons in different cortical layers exhibit distinct structural plasticity of apical dendritic spines, which may arise from their distinct functional roles in cortical circuits. Second, we focus on molecular mechanisms of spine and cortical circuit structural plasticity. Here we show that retinoic acid (RA) signaling plays an essential role in dendritic spine experience-dependent plasticity in vivo. Finally, combining in vivo two photon calcium imaging with behavioral analysis, we investigate the effect of stress on neuronal responses and functional responses of layer 2/3 neurons, which play an important role in sensory processing. The proposed studies will provide circuit-level insight into how the cortex responds to changes in the environment.