Fig. 5

vps4aT248I mutants have selective defects in vestibular circuitry. A, 5 dpf vps4aT248I mutants (N = 16) do not have a significantly different VIEM compared with wild-type siblings (N = 18); Mann?Whitney test; p = 0.4632 (exact). B, 5 dpf vps4aT248I mutants (N = 10) have a reduced VSR compared with wild-type siblings (N = 7); Mann?Whitney test; p = 0.0012 (exact). C, Simplified schematic showing the flow of information evoked by head rotation from the inner ear to hindbrain nuclei, vestibuloocular neurons, and motor neurons. UHC, utricular hair cells; CN VIII, VIIIth nerve; SVN, superior vestibular nucleus; VS, vestibulospinal cells; TAN, tangential neurons; M, Mauthner cell; CN IV, trochlear nucleus; CN III, oculomotor nucleus; OM, oculomotor muscles. D, 5 dpf larva showing basal GCaMP7a expression and backfill injected rhodamine dextran marking the Mauthner cell (M). White dotted lines indicate the presumptive TAN, SVN, and VS regions, and a solid yellow line designates a dextran filled VS neuron. Other landmarks include fibers running parallel and perpendicular fibers to the inner ear cavity (yellow arrows), a lateral cleft between mid- and hindbrain lobes (white arrowhead) and portion of the occipital arch cartilage (yellow asterisk). D?, Pre- and poststimulus GCaMP7a levels in vestibular region in a representative wild-type sibling and vps4aT248I mutant. The TAN, SVN, and VS ROIs are outlined by dotted lines. E, Average trace of normalized fluorescence (F) for the TAN, SVN, and VS of wild-type siblings and vps4aT248I mutants during auditory stimulation at 600 Hz. F, Percentage change in fluorescence of the presumptive TAN, SVN, and VS of wild-type siblings and vps4aT248I mutants during auditory stimulation at 600 Hz. The VS in vps4aT248I mutants (N = 11) have a reduced change in fluorescence compared with wild-type siblings (N = 15); unpaired t test; p = 0.0337; t = 2.252; df = 24. Single VS neurons in vps4aT248I mutants (N = 9 cells from 4 larva) also have a reduced change in fluorescence compared with wild-type siblings (N = 26 cells from 14 larva); unpaired t test; p = <0.0001; t = 6.195; df = 33. There is no significant difference between mutants and wild-type siblings in the TAN (unpaired t test; p = 0.1405; t = 1.524; df = 24) or SVN (unpaired t test; p = 0.6224; t = 0.4988; df = 24).