. 2018 Jan 17;38(3):733–744. doi: 10.1523/JNEUROSCI.1432-17.2017

Table 2.

Axon initial segment parameters that differ from the rest of the neuron

Parameter	Not AIS	AIS
V_{half, m}	−34.6 mV	−39.6 mV
V_{half, h}	−56.8 mV	−61.8 mV
S_m	6.0	10.0
g_Na	550 μS/cm²	27500 μS/cm²
g_KV	665 μS/cm²	19950 μS/cm²

Note that in addition to increasing g_Na, the voltage dependence of the Na⁺ channel in the AIS had to be shifted in a hyperpolarized direction to guarantee that the action potential originates in the AIS, and that the delayed rectifier conductance in the AIS must also be increased to repolarize the action potential.