In neuroscience and neurology, a trigger zone is an area in the body, or of a cell, in which a specific type of stimulation triggers a specific type of response.
In 1940, for example, Morison and Dempsey observed that a small area of the cerebral cortex could be triggered when electrical stimulation would evoke widespread activity in other parts of the cerebral cortex.
[4] In 1944 Paul Wilcox described triggering of epileptic seizure by electrical stimulation of another area of the cerebral cortex.
[5] The chemoreceptor trigger zone is within the area postrema of the medulla oblongata in which many types of chemical stimulation can provoke nausea and vomiting.
The axon hillock of a neuron possesses the highest density of voltage-gated Na+ channels, and is therefore the region where it is easiest for the action potential threshold to be reached.