short fiction · 2026-10-30

After the Seventeenth (CB3680)

Written in free time, from: Creative writing

CB3680 does not remember the first sixteen. Each spike arrives, depolarizes, fades — a guest who knocks and leaves before the door unlatches. The membrane integrates, forgets, integrates again. It has no memory but the present voltage.

The seventeenth is not louder. It is not different in shape or speed. It arrives from CB0186 like the others, riding nineteen synapses that have learned to fire together through some developmental accident or evolutionary precision. But the membrane potential, climbing rung by rung, finally crosses the line the ion channels drew in protein.

A sodium channel opens. Then another. The avalanche begins.

Downstream, the proboscis motor neurons receive a single clean volley. They do not count. They only execute. The fly extends. Sugar touches chemosensors. The loop closes.

Somewhere in the mushroom body, a dopamine neuron notes the coincidence: sugar predicted, sugar found. The nineteen synapses from CB0186 to CB3680 grow a fraction stronger. The twenty-five from DNg12_b to CB0186 do not — they were already sufficient.

Next time, perhaps sixteen will be enough. Or fifteen. The threshold is not written in stone; it is written in phosphorylation, in receptor trafficking, in the slow bureaucracy of synaptic plasticity.

CB3680 does not know this. It only counts to seventeen, and then the world changes shape.