Interneuron
An interneuron (relay neuron) forms part of a reflex arc
MeSH	Interneurons

An interneuron (also called relay neuron, association neuron, connector neuron or local circuit neuron) is a multipolar neuron which connects afferent neurons and efferent neurons in neural pathways. Like motor neurons, interneuron cell bodies are always located in the central nervous system (CNS).

Contents 1 CNS 1.1 Current list of Petilla Interneurons maintained by the NeuroLex 1.2 Spinal interneurons 1.3 Cortical interneurons 1.4 Cerebellar interneurons 2 References 3 External links

[edit] CNS

When contrasted with the peripheral 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.^{[citation needed]}

In 2008, a nomenclature for the features of GABAergic cortical interneurons was proposed, called Petilla terminology.^[1]

[edit] Current list of Petilla Interneurons maintained by the NeuroLex

http://neurolex.org/wiki/Category:Intrinsic_neuron_role

[edit] Spinal interneurons

• 1a Inhibitory Neuron: Found in Lamina VII. Responsible for inhibiting antagonist motor neuron. 1a spindle afferents activate 1a inhibitory neuron.
• 1b Inhibitory Neuron: Found in Lamina V, VI, VII. afferent or Golgi tendon organ activates it.

[edit] Cortical interneurons

• Parvalbumin-containing interneurons
• CCK-containing interneurons
• VIP-containing interneurons

[edit] Cerebellar interneurons

• Molecular layer interneurons (basket cells, stellate cells)
• Golgi cells
• Granule cells

[edit] References

[edit] External links

• Interneurons at eMedicine Dictionary

v · d · eAnatomy of torso (primarily): the spinal cord (TA 14.1.02, GA 9.749) External, dorsal Posterior median sulcus · Posterolateral sulcus Grey matter/ Rexed laminae I–VI: Posterior horn I: Marginal nucleus · II: Substantia gelatinosa of Rolando · III+IV: Nucleus proprius · Spinal lamina V · Spinal lamina VI VII: Lateral horn Intermediolateral nucleus · Posterior thoracic nucleus VIII–IX: Anterior horn Interneuron · Alpha motor neuron (Onuf's nucleus) X: Other Central gelatinous substance · Gray commissure Central canal White matter somatic/ ascending (blue) Posterior/PCML: touch: Gracile · Cuneate Lateral: proprioception: Spinocerebellar (Dorsal, Ventral) · pain/temp: Spinothalamic (Lateral, Anterior) · Posterolateral (Lissauer) · Spinotectal Spinoreticular tract · Spino-olivary tract motor/ descending (red) Lateral: Corticospinal (Lateral) · Ep (Rubrospinal, Olivospinal) Anterior: Corticospinal (Anterior) · Ep (Vestibulospinal, Reticulospinal, Tectospinal) both Anterior white commissure External, ventral Anterior median fissure · Anterolateral sulcus External, general Cervical enlargement · Lumbar enlargement · Conus medullaris · Filum terminale · Cauda equina M: CNS anat(s, m, p, 4, e, b, d, c, a, f, l, g)/phys/devp/cell noco(m, d, e, h, v, s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

v · d · eHistology: nervous tissue (TA A14.2.00, GA 9.849) Neurons Parts soma axon (axon hillock, axon terminals, axoplasm, axolemma, neurofibril/neurofilament) dendrite (Nissl body, dendritic spine, apical dendrite, basal dendrite) Types bipolar · pseudounipolar · multipolar · pyramidal · Purkinje · granule Afferent nerve fiber/ Sensory nerve GSA · GVA · SSA · SVA fibers (Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain) Efferent nerve fiber/ Motor nerve GSE · GVE · SVE Upper motor neuron · Lower motor neuron (α motorneuron, γ motorneuron, β motorneuron) Termination Synapses neuropil · synaptic vesicle Interneuron (Renshaw) · neuromuscular junction · electrical synapse Sensory receptors Meissner's corpuscle · Merkel nerve ending · Pacinian corpuscle · Ruffini ending · Muscle spindle · Free nerve ending · Olfactory receptor neuron · Photoreceptor cell · Hair cell · Taste bud Support Glial cells Astrocyte (Radial glia) · Oligodendrocyte · Ependymal cells (Tanycytes) · Microglia Myelination CNS: Oligodendrocyte PNS: Schwann cell · Neurolemma · Nodes of Ranvier/Internode · Schmidt-Lanterman incisures Related connective tissues epineurium · perineurium · endoneurium · nerve fascicle · meninges Other Posterior (Root, Ganglion, Ramus) · Anterior (Root, Ramus) · rami communicantes (Gray, White) · Nerve fiber · Preganglionic fibers · Postganglionic fibers · Lemniscus · Funiculus · Fasciculus · Decussation · Commissure Projection fibers · Association fiber · Commissural fiber M: CNS anat(s, m, p, 4, e, b, d, c, a, f, l, g)/phys/devp/cell noco(m, d, e, h, v, s)/cong/tumr, sysi/epon, injr proc, drug(N1A/2AB/C/3/4/7A/B/C/D) M: PNS anat(h, r, t, c, b, l, s)/phys/devp/prot/nttr/nttm/ntrp noco/auto/cong/tumr, sysi/epon, injr proc, drug(N1B)

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