<P> The axon hillock is the last site in the soma where membrane potentials propagated from synaptic inputs are summated before being transmitted to the axon . For many years , it had been believed that the axon hillock was the usual site of action potential initiation . It is now thought that the earliest site of action potential initiation is found just adjacent , in the initial ( unmyelinated ) segment of the axon . However , the positive point , at which the action potential starts , varies between cells . It can also be altered by hormonal stimulation of the neuron , or by second messenger effects of neurotransmitters . </P>
<P> The axon hillock is the last site in the soma where membrane potentials propagated from synaptic inputs are summated before being transmitted to the axon . For many years , it had been believed that the axon hillock was the usual site of action potential initiation . It is now thought that the earliest site of action potential initiation is found just adjacent , in the initial ( unmyelinated ) segment of the axon . However , the positive point , at which the action potential starts , varies between cells . It can also be altered by hormonal stimulation of the neuron , or by second messenger effects of neurotransmitters . </P>
where is an action potential initiated in a neuron
where is an action potential initiated in a neuron
in the initial ( unmyelinated ) segment of the axon
in the initial ( unmyelinated ) segment of the axon