Unit name: Neural Circuit

Key words: neural circuit, neural development, gene, neural activity

      Neural circuits process information in the brain and form the basis of brain activities. These neural circuits are developmentally established after a process including cell differentiation, axon guidance, and synapse formation during neural development (Fig. 1). However, the molecular mechanism by which the complicated neural circuit network forms as a result of these individual phenomena has not yet been clarified. This Research Unit “Integrated Neural Circuits” consists of a comprehensive research team, and has performed overall research at levels from molecules to whole organisms (micro-macro levels). For example, we aim to clarify the molecular function of neural circuits using molecular biological methods and formation of the neural system using developmental engineering techniques in mice.

Fig. 1: Process of neural circuit development

 Methods for approaching the brain network

Fig. 2: Visual information processing pathways [lleman, DJ and Van Essen, DC. (1991) Distributed hierarchical processing in the primate cerebral cortex. Cerebral Cortex 1: 1-47.]

      To understand brain activities, the brain network should be uncovered. To do so, however, it was not sufficient if we only described the brain network as shown in Fig. 2 similar to computer circuits. For full understanding of brain activities, research on all levels: molecules, genes, cells, cell networks, functions, and human behaviors (Fig. 3), is required. To date, each researcher individually investigated only in each own area, resulting in obtaining fragmental information on the brain network. Therefore, our research unit has collaboratively combined different expertise. As a result, our effort has found new genes that may be associated with psychiatric disorders or behavioral abnormalities.

Fig. 3: Brain activities

 Understanding of behavior that genes induce

       We are able to search for the chromosomal location of gene alteration causing this disorder by directly comparing genomic data, which a member of our research group built, between on Japanese patients with schizophrenia and on healthy persons.

Searching on our genomic database for a new gene found to be associated with behavioral abnormality in mice, the genotype was compared between the group with the disorder and healthy group. As a result, there was a possibility that this gene is associated with bipolar disorder.

Thus, joint comprehensive research in multiple fields may facilitate the understanding of the operating principles of neural circuits and their abnormalities.