gfA^PΔ14G flies perform no differently to wild-type flies in terms of flight, olfactory behavior, and in visual tests.

gfA^PΔ14G flies have a defect in the jump circuit between the peripherally synapsing interneuron (PSI) branch of the giant fiber and the dorsal lateral muscle (DLM) motor neuron. This is demonstrated by intracellular recordings of DLMs following giant fiber stimulation; while the DLMs of wild-type flies can follow stimulation frequencies of up to 100 Hz, gfA^PΔ14G DLMs respond robustly to stimulation at frequencies of 1 and 10 Hz, but start to fail when stimulated at 100 Hz. The defects are specific to the synapses between the PSI and DLM motor neurons as the tergotrochanteral muscles are able to follow the giant fiber stimulation at 100 Hz without any problem.

The tergotrochanteral muscle of gfA^PΔ14G flies is able to respond to low-strength electrical stimulation, which activates the elements presynaptic to the giant fiber, which in turn activate the giant fiber, in a wild-type fashion, showing both sort- and long-latency responses.