interneuron

An interneuron is a nerve cell that sits in the middle of a circuit, passing messages between other nerve cells rather than reaching out to muscles or sense organs. Think of a relay between two phone callers: the message comes in from one neuron, the interneuron does a quick bit of sorting, and the message goes out to another neuron right nearby. Most interneurons are short-range cells that stay within one local patch of the brain or spinal cord and never send their wiring off to distant body parts.

Interneurons are the workhorses of decision-making in the nervous system. Some of them excite their neighbors, nudging a signal forward, while many others quiet their neighbors down, acting like a brake that keeps activity from running wild. By mixing these pushes and brakes, a single interneuron can decide whether an incoming signal gets amplified, blocked, or reshaped before it continues. This is how circuits filter noise, sharpen timing, and produce the fast, finely tuned behavior we rely on every moment.