What sets the highest rate at which a neuron can fire? · Lobeworks/17

The absolute refractory period.

What sets the highest rate at which a neuron can fire?

The absolute refractory period. No second spike can start until enough sodium channels have recovered from inactivation, so a period tabst_{\text{abs}}tabs​ allows at most fmax⁡≈1/tabsf_{\max} \approx 1/t_{\text{abs}}fmax​≈1/tabs​ spikes per second: about 1000 for 1 ms. Real neurons stay well under that ceiling, the fastest at a few hundred per second, because the relative period and the potassium currents that follow each spike stretch every interval further.