In most mammalian central nervous system neurons, the action potential (AP) is initiated at the proximal axon region and propagates forward and backward. These results may inspire the construction of neuronal models to predict the propagation of bpAPs in dendrites with enormous variation in morphology, to further illuminate the role of bpAPs in neuronal communication. The diversity among the bpAPs recorded in different neurons was mainly due to differences in dendritic morphology. These findings indicate that the dendritic diameter and branching pattern significantly influence the properties of bpAPs. Simulation results from neuron models with different dendritic morphology corresponded well with the experimental results. Similar to velocity, the amplitude of bpAPs was also positively correlated with dendritic diameter, and the attenuation patterns of bpAPs differed among different dendrites. In addition, when bpAPs passed through a dendritic branch point, their velocity decreased significantly.
The velocity of a bpAP was positively correlated with the diameter of the dendrite on which it propagated. We found that the velocity of bpAPs was not uniform in a single dendrite, and the bpAP velocity differed among distinct dendrites of the same neuron. By taking advantage of Optopatch, an all-optical electrophysiological method, we made detailed recordings of the real-time propagation of bpAPs in dendritic trees. Due to limited spatial resolution, it has been difficult to explore the specific propagation process of bpAPs along dendrites and examine the influence of dendritic morphology, such as the dendrite diameter and branching pattern, using patch-clamp recording. Its properties (velocity and amplitude) can be affected by dendritic morphology. The back-propagating action potential (bpAP) is crucial for neuronal signal integration and synaptic plasticity in dendritic trees.
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