In the neuronal membrane, the region where action potentials are usually generated is called the spike-initiation zone. The spike-initiation zone for action potentials varies in different types of neurons.
For typical neurons in the brain or spinal cord, the
, where an axon originates from the soma, is the initiation zone for action potentials. Depolarizing stimuli from the synapses formed between other neurons and the neuron of interest will induce action potentials when this region is depolarized to the threshold.
In most sensory neurons, action potentials are initiated near the
. Sensory stimulation at this region depolarizes the membrane and leads to propagating action potentials along the sensory nerves.