Elucidation of Neural Circuit

We uncovered a neural circuit mediating the fly’s directional response to light and gravity. A set of four neurons deep within the brain controls the animal’s directional response to light sensation and gravity. When these neurons are functionally silenced, the animal’s light and gravitational responses are reversed; they walk away from light and in the direction of gravity, the opposite of their normal behaviors. Another site for regulation of phototactic and geotactic responses is the Ellipsoid Body, a component of the central brain structure known as the Central Complex. We also study how visual experience is remembered, particularly with regard to the wavelength of light, as flies make directional choices in a walking maze. In a genetic screen, we identified mutant animals that cannot form a memory of the association of light with aversive heat. We are now characterizing the genes that are required to form this memory. Our plan is to identify the full circuitry controlling these behaviors, from sensory input to motor output. An exciting prospect is to examine how these circuits differ in architecture and function in fruitflies that display distinct light and/or gravity directed behaviors, including other Drosophila species.