Mutants have impaired visual pattern memory.

nob^KS49/nob^KS49 flies show significantly longer jump latencies compared to wild type in a CO[2] laser beam assay (thermal nociception induces a jump response) and in a heat plate assay (but show normal behavior in a jump test).

The middle part of the protocerebral bridge is missing in nob^KS49 adult brains. Total walking activity is significantly decreased in comparison to wild-type flies. Episodes of high walking probability occur as frequently as in wild-type flies, but these episodes are of much shorter duration than in wild type.

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. nob^KS49; for^R larvae show "sitter-like" foraging behaviour.

Females display increased ovulation and low receptivity after Acp70A injection.

Flies have a reduced climbing activity due to a reduced average walking speed and to a spastic state. Mean longevity is drastically reduced. Flies are impaired in habituation and in Pavlovian conditioning of the proboscis extension reflex. Mutants have difficulty in 'data-exchange' between the two brain hemispheres as shown by using an ipsi- and contralateral stimulation procedure.

No protocerebral bridge.

Protocerebral bridge open in the middle; on either side of midline. Glomeruli 1-3 absent and glomeruli 4-6 are increased in size (glomeruli 7 and 8 look normal). In 5% of animals ellipsoid body is open ventrally and fan body may have a cleft.

Hemizygous males have normal viability throughout development and the developmental rate at 25^oC is normal. Homozygous adult females are rarely seen. These females are fragile and do not produce offspring. nob^KS49/Df(1)HC244 females have a higher viability than homozygous females. Hemizygous adult males and females have a normal external appearance. The protocerebral bridge of the central complex is grossly deformed. It is interrupted in the middle, and medially the neuropil is distorted and bulging. Glomeruli are missing close to the midline. Some intrinsic fibres extend across the midline. The rest of the central complex is less severely affected, although in some cases there is a "cleft" in the fan-shaped body along the midline. The number of fibres in the central complex is reduced in prepupae. Hemizygous adults have a reduced maximal and average walking speed. Leg coordination is disturbed after short interruptions in walking, with missing swing phases, mostly of hind legs, or extra steps of individual legs being observed. Turns during smooth walking are sometimes disturbed. Occasionally leg coordination breaks down such that the fly is left in a semiparalytic state, from which the flies recover spontaneously. Flies show reduced initial walking activity in a "Buridan's Paradigm" test compared to wild-type, and the walking activity declines to near zero within 6 minutes. Gynandromorph analysis indicates that the focus for the walking defects in nob^KS49 flies is in the head. Flies show a marked avoidance of light in a slow phototaxis assay, and fast phototaxis is severely reduced. Flies have a reduced tendency to escape when mechanically stimulated. Optomotor responses are normal in tethered flight, but the amplitude of spontaneous torque modulations as well as the number of torque spikes are reduced.

Disorganized protocerebral bridge. Deficient in olfactory learning.

Protocerebral bridge between left and right sides of adult brain seems disintegrated into two or more glomeruli; fiber number in interhemispheric commissure of white pupa reduced; learning is poor in "arena paradigm" tests of adults, using sugar and odorants (Heisenberg et al., 1985); larval learning test using electric shocks and odorants gave approximately half the normal score (Heisenberg, unpublished). Locomotor activity of mutant adults is abnormal (spontaneous walking speed, regarding forward strides of legs, is slow) and in flight, there is reduced frequency of flight starts, altered "object response" and reduced occurrences of "body saccades" (Heisenberg). Adults exhibit aberrant habituation of proboscis-extension reflex (Bouhouche and Vaysse, 1991).