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Please forgive what may be an elementary question for many of you.

I am trying to understand the range of firing rates in an idealized neuron. I understand what governs the maximum firing rate of a neuron (the refractory period), however I would like to know how to figure out what the minimum firing rate would be.

The context of this neuronal excitation would be one of applying a constant, sustained electrical stimulus which barely satisfies the threshold requirement for an action potential to occur in the neuron. Put otherwise, the neuron would be exposed to the lowest level of sustained stimulation required to cause a steady spike train.

I have found information on average firing rates (in various species and in various parts of the nervous system and in response to various amplitudes of stimuli), but I have not found anything yet which describes how to find the lowest rate of firing in an idealized neuron. I also am unclear as to whether the threshold of an action potential refers to the minimum required to cause a single, solitary action potential (and it will not be repeated even if the stimulus is kept steady) OR if the threshold implies that the action potential would be repeated steadily. Please forgive my ignorance of the subject, as I am only just starting to study this fascinating and intimidating subject.

Thank you for your time and consideration!

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    $\begingroup$ Welcome. I think this question depends on a number of factors. One major variable is the kind of stimulus you are talking about - chemical (neurotransmitters/drugs) or electrical stimulation (ion gradients/current stimuli)? Even more importantly, what kind of neuron do you have in mind? There are neurons, e.g. in the auditory nerve, that have high intrinsic firing rates, perhaps even in the absence of external stimuli (that I have to look up). Also in the thalamocortical system there are neurons that have intrinsic firing rates (pacemaker neurons). $\endgroup$ – AliceD♦ Apr 7 '20 at 20:12
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    $\begingroup$ Might be worth reading about sodium channel inactivation. Coincidentally, I just answered a related question on Biology.SE: biology.stackexchange.com/questions/92479/… There the question was about increased excitability, though for yours the same holds for a decrease in excitability. In any event, there won't be any generalizable answer to your question. If you look at certain populations you may find observed minima but this is not based on the mechanism you describe. $\endgroup$ – Bryan Krause Apr 7 '20 at 20:32

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