Neural basis of reproductive isolation: Neural circuits for courtship and rejection.

To elucidate the neural mechanism of reproductive isolation, we cast a spotlight on a Gobiida small fish, freshwater goby. Male gobies could discriminate females just with visual perception, and choose their reaction correctly between courtship and threatening behaviors. Expression patterns of c-fos, a marker for neural activity, revealed that the courtship behavior activated the ventral part of ventral telencephalon and the preoptic area, while the threatening induced the activity of the intermediate pituitary, suggesting that several brain regions related to the behavioral output show different responses between two behaviors. The telencephalon of freshwater goby exhibits some remarkable features; a complicated structure of the lateral part of dorsal telencephalon, the visual center of teleosts, and a striatum-like ventral telencephalic component. In future, we will examine whether these characteristic brain regions work as the center for behavioral selection.