Monoaminergic Orchestration of Motor Programs in a Complex C. elegans Behavior
(A, B) Acute modulation of the activity of DD GABA neurons in transgenic animals expressing channelrhodopsin (ChR2) and halorhodopsin (NpHR) in DD motor neurons (Pflp-13::ChR2::GFP; Pflp-13::NpHR::CFP) induces turning behavior. Blue light activation of GABAergic DD motor neurons that synapse onto dorsal muscles induces ventral turning. Green light inhibition of GABAergic DD motor neurons induces dorsal turning. (A) Quantification of bending behavior with green and blue light exposure. Bending bias was calculated as the fraction of dorsal turns – fraction of ventral turns after blue (DD activation, blue bars) or green (DD inhibition, green bars) light exposure. Each bar represents the mean bending bias for a minimum of 45 animals per genotype. Statistical significance as indicated: **p<0.001 and ***p<0.0001, two-tailed Student's t test. (B) Locomotion traces signify the time course of blue and green light exposure during forward movement (red). Open circles denote 1-s time marks. The compass indicates anterior (A), posterior (P), ventral (V), and dorsal (D) directions. Kymographs display sinusoidal bending wave amplitude before, during, and after light exposure. Normalized curvature is plotted at each point along the worm's centerline in units of inverse worm lengths. Color indicates curvature in either the ventral (red) or dorsal (blue) direction. The colored bands widen and brighten during deep turns induced by light exposure: white horizontal dotted lines indicate duration of light exposure, Ventral indicates a deep ventral bend, and Dorsal indicates a deep dorsal bend. Still images were taken at * location on worm track (Movie S3). Yellow triangle indicates the position of the vulva.