How do potassium channels end each spike and decide how fast a neuron can fire? · Grey Matter

Voltage-gated potassium channels open a little after the sodium channels, as the spike rises, and the potassium leaving the cell pulls the voltage back down while the sodium channels inactivate.

How do potassium channels end each spike and decide how fast a neuron can fire?

Voltage-gated potassium channels open a little after the sodium channels, as the spike rises, and the potassium leaving the cell pulls the voltage back down while the sodium channels inactivate. Fast-closing types end the spike quickly and let the cell recover within a millisecond or two, which is how fast-spiking interneurons sustain hundreds of spikes per second. Slower potassium currents, some activated by the calcium that enters with each spike, build up during a train and produce a lasting afterhyperpolarisation, so the cell slows down (adaptation). Which potassium channels a neuron expresses is therefore a large part of its firing personality.