Studies of Neural Circuit Structure by Analysis of Single Neuron Morphology
Abstract: To understand mechanisms of neural networks, we explore structures of the networks by tracing morphologies of single neurons which are involved in the networks and further investigate correlation between the characteristics of the network structure and properties of neural activity. Here, I show three examples of experiments in our strategy. One: axon collaterals which had been derived from corticospinal neurons were visualized by GFP expression after infection with a recombinant Sindbis virus. We traced the labeled axons one by one and found that the striatum, zona incerta and pontine nuclei received the axon collaterals frequently. Two: dendrites of neurons in the neostriatum were visualized using the recombinant virus and were analyzed with respect to appositions of immunolabeled excitatory axon terminals under a confocal laser scanning microscope (CF-LSM) and scanning electron microscope equipped with focused ion beam (FIB-SEM). Synapses between thalamostriatal terminals and GFP-labeled dendrites were observed in the 3D ultrastructure data which was obtained under the FIB-SEM. Three: in the rat whisker system, correlations between distribution of thalamocortical axons and size of receptive fields were revealed by juxtacellular labeling method. I bereave that these bottom-up experiments contribute to building theoretical models which explain mechanisms of neural circuits.
Key words: neural network, structure and function, recombinant virus, FIB-SEM, juxtacellular labeling