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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. [2] For many years, it was believed that the axon hillock was the usual site of initiation of action potentials—the trigger zone.
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.. The term was first used in this context around 1914 by Hugh T. Patrick, who was writing about trigeminal neuralgia, a condition in which pain fibers in the trigeminal nerve become hypersensitive. [1]
This region is characterized by having a very high concentration of voltage-activated sodium channels. In general, it is considered to be the spike initiation zone for action potentials, [18] i.e. the trigger zone. Multiple signals generated at the spines, and transmitted by the soma all converge here. Immediately after the axon hillock is the ...
A diagram of the proteins found in the active zone. The active zone is present in all chemical synapses examined so far and is present in all animal species. The active zones examined so far have at least two features in common, they all have protein dense material that project from the membrane and tethers synaptic vesicles close to the membrane and they have long filamentous projections ...
From the axon hillock, an action potential can be generated and propagated down the neuron's axon, causing sodium ion channels in the axon to open as the impulse travels. Once the signal begins to travel down the axon, the membrane potential has already passed threshold, which means that it cannot be stopped. This phenomenon is known as an all ...
It is a simple device which uses a mirror in a box to create an illusion in which the sensory system perceives that it is seeing two hands instead of one, therefore allowing the sensory system to control the "phantom limb". By doing this, the sensory system can gradually get acclimated to the amputated limb, and thus alleviate this syndrome. [36]
Human nervous system. Human nervous system – the part of the human body that coordinates a person's voluntary and involuntary actions and transmits signals between different parts of the body. The human nervous system consists of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
In neuroscience, the axolemma (from Greek lemma 'membrane, envelope', and 'axo-' from axon [1]) is the cell membrane of an axon, [1] the branch of a neuron through which signals (action potentials) are transmitted. The axolemma is a three-layered, bilipid membrane. Under standard electron microscope preparations, the structure is approximately ...