Audiograms demonstrate mutants show essentially no response at any sound intensity. Homozygotes are rare unless grown in uncrowded larval conditions. Adults exhibit age-dependent circling behaviour, correlated with degeneration in the brain. Optic lobes coalesce into a dense mass, cohesiveness between axon tracts is lost and the cortex shows degeneration. Ommatidial units in the retina dissociate from one another.
Within as few days of eclosion individuals circle in large arcs, progressing with age to smaller circles, eventually spinning on the spot. Finally individuals stand still appendages trembling before death. The optic lobes degenerate in spinning flies, photoreceptor cells lose connectivity to optic lobes.
