Interactive figure: one electrode hears many neurons at once

Listening to neurons with unknown cell type identities

If you placed an electrode inside Santiago Ramón y Cajal’s drawing of the cerebellum, it would allow you to eavesdrop on the messages sent by every neuron inside the dashed circle. Each vertical line in the graph is the waveform of one “spike,” an electrical signal that is the basic unit of neural communication. Taller spikes come from cells closer to the electrode’s tip. Turn on sound to listen, or hover over the trace to see one spike up close.

This is a simulation of a neural recording. The signal mixes spikes from several cerebellar cell types over typical electrode background noise. Adding more electrodes can help parse out signals from individual neurons, but doesn’t automatically tell us their cell type identity. Electrode and listening range are drawn for illustration, not to scale.

Text description: Cajal’s drawing of the cerebellum in plain ink, with a dashed circle that represents the listening range of an electrode inserted from above. Beside it, a dense, two-second voltage trace containing spikes recorded by the same electrode. Spikes of different heights overlap over a noisy baseline; a few tall spikes stand out, but none of them is labeled with the neuron or cell type that produced it.