(A) A fluorescent image of zebrafish brain (dorsal view, anterior is up) showing the terminalis neurons and axons (arrows). (B) A schematic diagram showing the experimental setup for RGC recordings in response to olfactory and TN stimulation. The numbers correspond with the following conditions: 1, 2–sham or odor stimulation; 3, 4–activation or inhibition of dopamine receptors; 5, 6–activation or inhibition of GnRH receptors; 7, 8–manipulation of both dopamine and GnRH receptors. (C) An overview of EVT. Prior work (Tanaka, 1996; Leopold et al., 2006; Freiwald et al., 2009) suggests that it may be the extremes (red dots), and not the mean (black dots near the center of the circle), that produce strong responses in the brain.