Interneuron
Encyclopedia
An interneuron is a multipolar neuron which connects afferent neurons and efferent neurons in neural pathway
s. Found within the central nervous system
and the enteric nervous system
.
(PNS), the neurons of the central nervous system
(CNS), including the brain
, are all interneurons. However, in the CNS, the term interneuron is used for small, locally projecting neurons (in contrast to larger projection
neurons with long-distance connections). CNS interneurons are typically inhibitory, and use the neurotransmitter GABA
or glycine
. However, excitatory interneurons using glutamate also exist, as do interneurons releasing neuromodulators like acetylcholine
.
Examples of interneurons include the homeostasis neuron and sexual arousal neuron also connecting to the brain through the association neurons. This is theorized to help focus higher attention on relevant sensory input and help block out behaviorally irrelevant or unchanging input, such as the sensation of the backs of your thighs on a chair. The neurophysiological measure short-latency intracortical inhibition (SICI) is believed to be mediated by these inhibitory interneurons. Inhibitory interneurons are also thought to play an important role in the generation of neural oscillations
.
In 2008, a nomenclature for the features of GABAergic cortical interneurons was proposed, called Petilla terminology.
Neural pathway
A neural pathway, neural tract, or neural face, connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter...
s. Found within the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
and the enteric nervous system
Enteric nervous system
The enteric nervous system is a subdivision of the autonomic nervous system that directly controls the gastrointestinal system in vertebrates.It is derived from neural crest.-Function:...
.
CNS
When contrasted with the peripheral nervous systemPeripheral nervous system
The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...
(PNS), the neurons of the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
(CNS), including the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
, are all interneurons. However, in the CNS, the term interneuron is used for small, locally projecting neurons (in contrast to larger projection
Pyramidal cell
Pyramidal neurons are a type of neuron found in areas of the brain including cerebral cortex, the hippocampus, and in the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons were first discovered and...
neurons with long-distance connections). CNS interneurons are typically inhibitory, and use the neurotransmitter GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
or glycine
Glycine
Glycine is an organic compound with the formula NH2CH2COOH. Having a hydrogen substituent as its 'side chain', glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG cf. the genetic code.Glycine is a colourless, sweet-tasting crystalline solid...
. However, excitatory interneurons using glutamate also exist, as do interneurons releasing neuromodulators like acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
.
Examples of interneurons include the homeostasis neuron and sexual arousal neuron also connecting to the brain through the association neurons. This is theorized to help focus higher attention on relevant sensory input and help block out behaviorally irrelevant or unchanging input, such as the sensation of the backs of your thighs on a chair. The neurophysiological measure short-latency intracortical inhibition (SICI) is believed to be mediated by these inhibitory interneurons. Inhibitory interneurons are also thought to play an important role in the generation of neural oscillations
Neural oscillations
Neural oscillation is rhythmic or repetitive neural activity in the central nervous system. Neural tissue can generate oscillatory activity in many ways, driven either by mechanisms localized within individual neurons or by interactions between neurons...
.
In 2008, a nomenclature for the features of GABAergic cortical interneurons was proposed, called Petilla terminology.
Current list of Petilla Interneurons maintained by the NeuroLex
http://neurolex.org/wiki/Category:Intrinsic_neuron_roleSpinal interneurons
- 1a Inhibitory Neuron: Found in Lamina VII. Responsible for inhibiting antagonist motor neuronMotor neuronIn vertebrates, the term motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles...
. 1a spindle afferents activate 1a inhibitory neuron.
- 1b Inhibitory Neuron: Found in Lamina V, VI, VII. afferent or Golgi tendon organ activates it.
Cortical interneurons
- ParvalbuminParvalbuminParvalbumin is a calcium-binding albumin protein with low molecular weight .It has three EF hand motifs and is structurally related to calmodulin and troponin C...
-containing interneurons - CCK-containing interneurons
- VIP-containing interneurons
Cerebellar interneurons
- Molecular layer interneurons (basket cellBasket cellBasket cells are inhibitory GABAergic interneurons found in several brain regions: the molecular layer of the cerebellum, the hippocampus, and the cortex.-Cerebellum:...
s, stellate cellStellate cellIn neuroscience, stellate cells are neurons with several dendrites radiating from the cell body giving them a star shaped appearance. The three most common stellate cells are the inhibitory interneurons found within the molecular layer of the cerebellum, excitatory spiny stellate interneurons and...
s) - Golgi cellGolgi cellIn neuroscience, Golgi cells are inhibitory interneurons found within the granular layer of the cerebellum. They were first identified as inhibitory by Eccles et al in 1964....
s - Granule cellGranule cellIn neuroscience, granule cells refer to tiny neurons that are around 10 micrometres in diameter. Granule cells are found within the granular layer of the cerebellum , the dentate gyrus of the...
s