The action potential is the fundamental signal of neuronal cells. In mammalian neurons, this signal is generated in the initial segment of the axon by a fast sodium current mediated by voltage-gated sodium channels. Luiza Filipis and Marco Canepari have developed a unique method allowing the measurement of the sodium current in the axon initial segment during the action potential generation. This novel technique opens the gate to the full understanding of neuronal excitation and to the investigation of genetic diseases caused by neuronal excitability dysfunction.
Figure legend. Sodium current associated with an action potential in the axon initial segment of a layer-5 neocortical pyramidal neuron.
View online : Optical measurement of physiological sodium currents in the axon initial segment. Filipis L, Canepari M. J Physiol. 2021