Interneuron

Interneuron
Cartoon of a locust interneuron that integrates information about wind in order to control wing motor neurons during flight [1]
Details
Location	Nervous system
Identifiers
MeSH	D007395
NeuroLex ID	birnlex_2534
TH	H2.00.06.1.00058
FMA	67313
Anatomical terms of neuroanatomy [edit on Wikidata]

Interneurons (also called internuncial neurons, relay neurons, association neurons, connector neurons, intermediate neurons or local circuit neurons) are neurons that connect two brain regions, i.e. not direct motor neurons or sensory neurons. Interneurons are the central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS).^{[citation needed]} They play vital roles in reflexes, neuronal oscillations,^[2] and neurogenesis in the adult mammalian brain.^{[citation needed]}

Interneurons can be further broken down into two groups: local interneurons and relay interneurons.^{[3][need quotation to verify]} Local interneurons have short axons and form circuits with nearby neurons to analyze small pieces of information.^[4] Relay interneurons have long axons and connect circuits of neurons in one region of the brain with those in other regions.^[4] The interaction between interneurons allow the brain to perform complex functions such as learning, and decision-making.

Structure[]

In the neocortex (making up about 80% of the human brain), approximately 20–30% of neurons are interneurons.^[5] Investigations into the molecular diversity of neurons is impeded by the inability to isolate cell populations born at different times for gene expression analysis. An effective means of identifying coetaneous interneurons is neuronal birthdating.^[6] This can be achieved using nucleoside analogs such as EdU.^[7][6]

In 2008, a nomenclature for the features of GABAergic cortical interneurons was proposed, called Petilla terminology.^[8]

Spinal cord[]

• Ia inhibitory interneuron: Found in lamina VII. Responsible for inhibiting antagonist motor neuron. 1a spindle afferents activate 1a inhibitory neuron.
• 

  A spinal interneuron (relay neuron) forms part of a reflex arc
  Ib inhibitory interneuron: Found in lamina V, VI, VII. Afferent or Golgi tendon organ activates it.

Cortex[]

• Parvalbumin-expressing interneurons
• CCK-expressing interneurons
• VIP-expressing interneurons
• SOM-expressing interneurons^[9]

Cerebellum[]

• Molecular layer (basket cells, stellate cells)
• Golgi cells
• Granule cells
• Lugaro cells
• Unipolar brush cells

Striatum[]

• Parvalbumin-expressing interneurons^[10]
• Cholinergic interneurons^[11][12]
• Tyrosine hydroxylase-expressing interneurons^[13]
• Calretinin-expressing interneurons^[14]
• Nitric oxide synthase-expressing interneurons^[14]

Function[]

Interneurons in the CNS are primarily inhibitory, and use the neurotransmitter GABA or glycine. However, excitatory interneurons using glutamate in the CNS also exist, as do interneurons releasing neuromodulators like acetylcholine. Interneurons main function is to provide a neural circuit, conducting flow of signals or information between a sensory neuron and or motor neuron^{[citation needed]}.

See also[]

• Relay (disambiguation)

References[]