Individuals expressing FoxP^GD4320, from either P{GD4320}v15735 or P{GD4320}v15732, under the control of Scer\GAL4^Act5C.PI (in combination with Dicer-2, for a more efficient RNAi) frequently die as pupae and the surviving adults walk much lower distances and show a significant decrease in light-off jump habituation (as they show a considerably higher jump response during the entire course of the assay) than controls; adults expressing from P{GD4320}v15735, but not P{GD4320}v15732, also show a severe decrease in flight ability, as compared to controls.

Individuals expressing FoxP^GD4320, from either P{GD4320}v15735 or P{GD4320}v15732, under the control of Scer\GAL4^elav.PLu (in combination with Dicer-2, for a more efficient RNAi) show a decrease in flight ability and show significantly smaller mushroom body α-lobe tips, as compared to controls; adults expressing from P{GD4320}v15735, but not P{GD4320}v15732, also show a decrease in walking distance, as compared to controls; adults expressing from P{GD4320}v15735 also present a significantly lower average distance to the closest neighbor than controls.

Individuals expressing FoxP^GD4320 from P{GD4320}v15735, but not P{GD4320}v15732, under the control of Scer\GAL4^Mef2.247 (in combination with Dicer-2, for a more efficient RNAi) also show significantly smaller mushroom body α-lobe tips, as compared to controls.

Third instar larval neuromuscular junctions of individuals expressing FoxP^GD4320, from either P{GD4320}v15735 or P{GD4320}v15732, under the control of Scer\GAL4^elav.PLu, but not Scer\GAL4^Mef2.247, (and in combination with Dicer-2, for a more efficient RNAi) show an apparently enlarged postsynaptic side, as compared to controls.

Third instar larval class IV da neurons of individuals expressing FoxP^GD4320 from either P{GD4320}v15735 or P{GD4320}v15732 under the control of Scer\GAL4⁴⁷⁷ (in combination with Dicer-2, for a more efficient RNAi) show significantly smaller dendritic field areas, despite of insignificant changes in the total dendritic length and in the number of dendritic endings, as compared to controls; expression from P{GD4320}v15735, but not P{GD4320}v15732, also leads to a significant decrease in average dendritic length, as compared to controls.

Expression of FoxP^GD4320 under the control of Scer\GAL4^NP7175 in adult males results in &gar;βc Kenyon cells with similar resting membrane potential and spike threshold, but significantly increased spike latency, and significantly decreased input resistance and membrane time constants, compared to controls; firing rate as a function of depolarizing current strength is significantly reduced, compared to controls; spontaneous excitatory postsynaptic currents at -90 mV holding potential are similar to those of controls, but spontaneous excitatory postsynaptic potentials at holding potentials closer to resting potential are smaller and decay faster; A-type potassium current densities are significantly increased, compared to controls, with no effect on their steady state activation or inactivation curves.

Expression of FoxP^GD4320 under the control of Scer\GAL4^VT030604 in adults does not affect the biophysical characteristics of &gar;'β'c Kenyon cells, compared to controls.

Only 65% of males expressing FoxP^GD4320 under the control of Scer\GAL4^elav-C155 show any courtship behaviour (compared to over 90% of control males) at 25[o]C. Mutant males which do court show a significant reduction in courtship index (the proportion of time spent courting) compared to controls. At 29[o]C, the mutant males fail to court.

The courtship song of males expressing FoxP^GD4320 under the control of Scer\GAL4^elav-C155 at 25[o]C is altered compared to wild type: the interpulse interval is reduced and more variable than normal, average pulse song bout duration is increased and time spent singing is reduced.

Copulation latency and courtship index are unaffected in assays of control males mated to females expressing FoxP^GD4320 under the control of either Scer\GAL4^elav-C155 or Scer\GAL4^Act5C.PI at 25[o]C.

Animals expressing FoxP^GD4320 under the control of Scer\GAL4^Act5C.PI at 29[o]C die during the late pupal stage.

Males expressing FoxP^GD4320 under the control of either Scer\GAL4^elav-C155 or Scer\GAL4^Act5C.PI show significantly reduced escape in a heated flight assay and significantly reduced walking activity in a locomotion assay compared to controls.

Females expressing FoxP^GD4320 under the control of Scer\GAL4^Act5C.PI show a slight but significant reduction in escape in a heated flight assay compared to controls. Females expressing FoxP^GD4320 under the control of either Scer\GAL4^elav-C155 or Scer\GAL4^Act5C.PI show significantly reduced walking activity in a locomotion assay compared to controls.

Animals in which expression of FoxP^GD4320 under the control of either Scer\GAL4^elav-C155 or Scer\GAL4^Act5C.PI is restricted to the adult stage (using the temperature sensitive Scer\GAL80^ts.αTub84B allele) do not show defects in the male courtship index or in walking activity in a locomotion assay.

Adults expressing FoxP^GD4320 under the control of Scer\GAL4^elav.PLu (in the presence of Dcr-2^Scer\UAS.cDa to increase the efficiency of RNAi) can show significantly reduced avoidance of noxious temperature (46[o]C) compared to control flies, depending on the particular P{GD4320} insertion line used.

Adults expressing FoxP^GD4320 under the control of Scer\GAL4^elav.PLu (in the presence of Dcr-2^Scer\UAS.cDa to increase the efficiency of RNAi) show no significant change in the kinetics of high temperature (46[o]C) induced paralysis compared to control flies.