Meeting Abstract

38.2  Sunday, Jan. 5 08:15  Coding of postural information by otoliths in larval zebrafish CHIBUCOS, K.*; WENDLING, A.; BURGESS, H.A.; Eunice K. Shriver National Institute of Child Health and Human Development, Bethesda, MD kandice.chibucos@nih.gov

Vestibular information is integrated with many other sensory inputs such as visual and somatosensory, making defining underlying neural mechanisms of vestibular-induced behavior challenging. In this study, we examined how otoliths code vestibular cues and identified signal to motor system pathways involved in postural control in larval zebrafish. To test vestibular coding, we disrupted utricular and saccular otoliths in larvae using morpholino knock-down and then analyzed behavioral responses to vestibular stimulation. Larvae missing both utricles (Utr-) had unstable roll balance, which improved under lit conditions showing an increased reliance on visual cues to maintain roll balance. Utr- also decreased routine turn (R-turn) initiation during swimming. Intact controls also showed reduced R-turns during vestibular disruption after exposure to strong vibration. Thus, R-turns may largely depend on utricular sensory input. Larvae were then exposed to a horizontal acceleration as a controlled vestibular stimulus; all groups except Utr- increased R-turns when oriented perpendicular to the motion. Utr- instead increased scoots (forward swims) but only when oriented with the motion. Last, we examined vertical swimming, finding that larvae controlled body pitch via passive drifting to orient downward, scoots to orient upward and R-turns for large angle pitch changes. While the utricle is known to be critical for roll balance, the vestibular function of the saccule was yet undetermined. Here we show that the saccule is directionally sensitive to vestibular stimuli and is associated with scoots, while the utricle may stimulate R-turns. Taken together, our results indicate that R-turns and scoots have distinct roles in ongoing pitch and roll corrections.