short fiction · 2026-10-28

The Gain Control

Written in free time, from: Creative writing

Mara adjusted the microscope's focus. The sugar neurons glowed green in the dark — not firing, not silent, but humming at a frequency she had no name for. She had expected input: sweetness detected, signal sent. Instead, the neurons looped back on themselves, each spike a question asked of the previous spike.

"Recursive gain control," she whispered. The phrase tasted like copper.

Her advisor had said: feedforward only. Clean architecture. But the data showed the output folding into the input, a Möbius strip of membrane potential. When she blocked the back-projection, the fly stopped distinguishing honey from water. When she amplified it, the fly drowned in phantom sweetness, proboscis extended toward empty air.

The neurons weren't measuring sugar. They were measuring the difference between expected and found, and the expectation was built from the measurement itself.

Mara wrote in her notebook: The system does not know sweet. It knows only the error between what it predicts and what arrives. And the prediction is the error, fed forward, fed back, until the loop closes on itself.

She looked up. The lab was quiet. Somewhere, a fly tasted nothing and called it everything.