Did the brain evolution accelerate the speciation?; The neural mechanism of premating isolation.

We analyzed the construction of telencephalon in the adult brain of goby fish, depending on the cytoarchitectural observation and distribution patterns of transcriptional factors and neurochemical molecules (Kawaguchi et al., 2019). Now, we are trying to identify the structures of diencephalon and hypothalamus in the goby brain, based on developmental origins and neurochemical traits. When a female of the same species was put in the tank where a male established a nest, the male went back from a point near the female to the nest with shaking the caudal fin in a constant rhythm, regarding that this fin vibration might be the visual signal to invite the female to the nest. The distribution pattern of c-fos positive cells was different between in the brains of the courtship male and the aggressive male. Several brain regions, which were induced many c-fos positive cells depending on the courtship behavior, showed the intense distribution of er-alpha positive cells.

意思決定は人間の精神活動の中枢をなすが、意思決定に至る神経回路の道筋を人間で解明することは難しい。本研究では、人間と共通の仕組みながら単純な脳を持つ魚類をモデルとして、識別に伴って最適な行動を選択する過程を司る神経回路を理解する。行動選択は意思決定の根源的な素過程であることから、本研究の進展は意思決定の神経機構の解明に向けて、一般的なモデル動物の研究とは一線を画す登坂路を提供することが期待される。また本研究では、生殖的隔離の維持に関わる神経機構の解明を目指す。生殖的隔離は種分化をもたらす主要素の一つであることから、本研究は種分化を可能にした脳の働きの理解に繋がることが期待される。