Chemosensory-induced motor behaviors in fish.

Chemical sensory signals play a crucial role in eliciting motor behaviors. We now review the different motor behaviors induced by chemosensory stimuli in fish as well as their neural substrate. A great deal of research has focused on migratory, reproductive, foraging, and escape behaviors but it is only recently that the molecules mediating these chemotactic responses have become well-characterized. Chemotactic responses are mediated by three sensory systems: olfactory, gustatory, and diffuse chemosensory. The olfactory sensory neuron responses to chemicals are now better understood. In addition, the olfactory projections to the central nervous system were recently shown to display an odotopic organization in the forebrain. Moreover, a specific downward projection underlying motor responses to olfactory inputs was recently described.