ebo^KS263 mutant flies exhibit a normal external appearance. The ellipsoid body (EB) is broad and flat (resembling the homologous structure in non-dipteran insects). In 20% of mutants the fan-shaped body (FB) appears to be vertically divided in the middle.

Tethered ebo⁶⁷⁸ mutants fly readily and for extended period of time which may be longer than in wild-type. Average torque traces and optomotor response appear as in wild-type. However, the rate of torque spikes is greatly reduced in ebo^KS263 mutants. The overall spike rate is only about 60% of wild-type. The amplitude of the small torque oscillations in between spikes is also reduced. The size and shape of torque spikes in these mutants are not noticeably abnormal. ebo^KS263 mutants exhibit normal optomotor response dynamics.

In a closed-loop with a single stripe (flight simulator), ebo^KS263 mutants behave close to normal. For over 85% of their flight time they keep the stripe in a frontal (+/- 15[o]) position.

Mutants have impaired visual pattern memory.

The ellipsoid body ring is sometimes open along its ventral aspect in mutants.

Homozygous larvae show normal locomotor behaviour on agar (non-foraging surface), but show reduced locomotor behaviour (shorter path lengths) on yeast (foraging surface) compared to controls. Larvae perform normally in a roll over test.

Mushroom bodies appear wild-type.

Flight behaviour shows reduced amplitude in the small random oscillations of the torque trace (yaw torque activity). The frequency of torque spikes is slightly but not significantly reduced (torque spike frequency). Dynamics of the optomotor response is normal (optomotor reversal time). Flies behave close to normal in a single stripe flight simulator (on-target fixation). Gyandromorphs demonstrate the behavioural phenotypes yaw torque activity and torque spike frequency are all highly correlated with the phenotype of the ellipsoid body.

Ellipsoid body usually open ventrally (kidney shaped or horizontal bar shaped) and may dissociate. Phenotype of ebo¹⁰⁴¹ stronger than that of ebo⁶⁷⁸, which in turn is stronger than ebo^KS263. ebo^KS263 originally showed optic lobe defects but this affect is no longer apparent.

Ellipsoid body is flat and broadened. Olfactory learning normal.

Ellipsoid body of central brain abnormally flat and broad; learning normal in tests using olfactory stimuli.