Tranquil, Elizabeth

Action potential repolarization in certain neurons slows at neurotransmitter release sites in the axon if an action potential is preceded by sufficient depolarization. We hypothesize that slower repolarization allows axons to change strength of neurotransmission by changing calcium channel open probability. This was explored with a Markov model comprised of multiple calcium channel subtypes and an action potential waveform input. The model was solved for channel open probability, channel ionic current and charge from ionic current. The outputted charge from the model was compared to experimental calcium imaging results in neurons from mouse cerebellum. The results show that more calcium flows into the cell when the action potential is widened. This implies that in some neurons, a wider action potential may lead to opening of calcium channels that respond selectively to the duration of the action potential waveform at sites of release.