From what I understand, the release of neurotransmitters into the synaptic cleft and the consequent binding of these to their respective receptors on the post-synaptic membrane can have one of the following effects: - excitatory: K+/Na+ ligand-gated ion channels are opened and the local transmembrane potential is decreased. If the treshold is not reached, multiple action potentials from synapses terminating in close proximity on the post-synaptic neuron's membrane can result in an action potential. - inhibitory: instead of K+/Na+ ion channels, Cl- or K+ ligand-gated ion channels are opened, increasing the local transmembrane potential. This decreases the chance that nearby excitatory synapses can generate an action potential. However, as this page, as well others, mentions, the axon hillock plays a crucial role in the integrating of the synaptic input received. Unfortunately, I've not been able to find any information on how this works. So in summary, what and how does the axon hillock 'work'?