Fig 1

Celsr3 is required for directionally unbiased acoustic startle escapes.

A) Schematic of a 5 dpf (days post-fertilization) larva (dorsal view) with a simplified diagram of the hindbrain circuit that drives the acoustic startle fast escape. +/- symbols indicate excitatory/inhibitory synapses. Dotted line indicates unknown connection. In response to a startling acoustic stimulus, Mauthner firing results in direct activation of contralateral motor neurons, leading to unilateral muscle contraction and a sharp turn (C1-bend). An iteration of this circuit model was previously used by the authors [87]. B) Representative right and left acoustic startle fast escapes in wild type 5 dpf larvae. Pre-Stimulus and C1-Bend: still images of when the acoustic stimulus was delivered (0 ms) and the highest angle of the Mauthner-dependent initial turn (C1-bend). Middle panel: 90 ms temporal projection of the response, including the C1-bend (begins arrow 1), counter bend (begins arrow 2), and subsequent swimming (begins arrow 3). Active Mauthner: predicted Mauthner that fired to drive right or left escape. C) Percentage of twenty acoustic stimuli that elicited any response (fast escape or response with >17 ms latency, with latency measured as first head movement following stimulus delivery). Each dot represents one fish. n = 126 siblings (mix of celsr3^+/+ and celsr3^-/+), 154 celsr3^-/- mutants. D) For larvae from (C), percentage of twenty acoustic stimuli that elicited a fast escape (latency <17 ms). 47% of mutant larvae responded within the sibling range (88–100%). E) For larvae from (D) that performed at least six fast escapes, initial C1-bend direction ratio (right versus left) for individual larva. Arrows indicate larvae that only turn one direction (“100% biased”; 24% of mutants). n = 126 siblings, 133 mutants.