Chase a moving target

What is being trained

The target's direction drives the LPLC1 neurons on that side of the fly; when it is close and large, the LC4 looming detectors join in. Two readouts of the 21 output neurons set turning and walking speed.

The score is the mean closeness, exp(−distance / 1.5 body lengths). Training uses a slow target; the held out test a faster, more erratic one.

Inspired by: Courtship chasing and the LC10 visual projection neurons (Ribeiro et al. 2018).

How to read the result

Fixed: the wiring, the synapse counts, the transmitter signs and the neuron model (Shiu et al. 2024). Learned: 44 readout numbers.

A rising curve alone proves little: a trained readout can often make use of any network. The evidence is in the comparison. Train the real circuit, save it, train a rewired control, and overlay the two held out curves. If the real wiring learns faster or generalises better, the specific map carries information the controls lack.

Senses: Target left or right → LPLC1 of that side; Target close and large → LC4 of that side. Readout neurons: DNa01 left, DNa01 right, DNa02 left, DNa02 right, DNa03 left, DNa03 right, DNb05 left, DNb05 right, DNa11 left, DNa11 right, DNp01 left, DNp01 right, MDN left, MDN right, DNp09 left, DNp09 right, DNg13 left, DNg13 right, DNp03 left, DNp03 right, MN9 (proboscis).

Training uses a 0.25 ms simulation step (the lab uses 0.1 ms); firing rates in these circuits differ by about 2 percent. Dataset: Subcircuit of FlyWire v783: inputs HSE, HSN, HSS, LPLC1, LC4, LPLC2, LC16, ORN_DM1, ORN_DA2, sugar/water, bitter; outputs DNa01, DNa02, DNa03, DNb05, DNa11, DNp01, MDN, DNp09, DNg13, DNp03, CB0701; paths with at least 40 synapses per step. About this dataset