Neuromodulation
Neuromodulation
Jump to navigation
Jump to search
Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. This is in contrast to synaptic transmission in which an axonal terminal secretes neurotransmitters to target fast-acting receptors of only one particular partner neuron. Neuromodulators are neurotransmitters that diffuse through neural tissue to affect slow-acting receptors of many neurons. Major neuromodulators in the central nervous system include dopamine, serotonin, acetylcholine, histamine, and norepinephrine. Neuromodulators are known to have modulatory effects on target areas such as decorrelation of spiking, increase of firing rate, sharpening of spatial tuning curves,[1] maintenance of increased spiking during working memory.[2]
A neuromodulator can be conceptualized as a neurotransmitter that is not reabsorbed by the pre-synaptic neuron or broken down into a metabolite. Such neuromodulators end up spending a significant amount of time in the cerebrospinal fluid (CSF), influencing (or "modulating") the activity of several other neurons in the brain. For this reason, some neurotransmitters are also considered to be neuromodulators, such as serotonin and acetylcholine.[3]
Neuromodulation is often contrasted with classical fast synaptic transmission. In both cases the transmitter acts on local postsynaptic receptors, but in neuromodulation, the receptors are typically G-protein coupled receptors while in classical chemical neurotransmission, they are ligand-gated ion channels. Neurotransmission that involves metabotropic receptors (like G-protein linked receptors) often also involves voltage-gated ion channels, and is relatively slow. Conversely, neurotransmission that involves exclusively ligand-gated ion channels is much faster.
A related distinction is also sometimes drawn between modulator and driver synaptic inputs to a neuron, but here the emphasis is on modulating ongoing neuronal spiking versus causing that spiking.
.mw-parser-output .toclimit-2 .toclevel-1 ul,.mw-parser-output .toclimit-3 .toclevel-2 ul,.mw-parser-output .toclimit-4 .toclevel-3 ul,.mw-parser-output .toclimit-5 .toclevel-4 ul,.mw-parser-output .toclimit-6 .toclevel-5 ul,.mw-parser-output .toclimit-7 .toclevel-6 uldisplay:none
Contents
1 Neuromuscular systems
2 Volume transmission
3 Neurotransmitter systems
3.1 Comparison
3.2 Noradrenaline system
3.3 Dopamine system
3.3.1 Dopamine pharmacology
3.4 Serotonin system
3.4.1 Serotonin pharmacology
3.5 Cholinergic system
3.6 GABA
3.7 Neuropeptides
4 Other uses
5 See also
6 References
7 External links
Neuromuscular systems[edit]
Neuromodulators may alter the output of a physiological system by acting on the associated inputs (for instance, central pattern generators). However, modeling work suggests that this alone is insufficient,[4] because the neuromuscular transformation from neural input to muscular output may be tuned for particular ranges of input. Stern et al. (2007) suggest that neuromodulators must act not only on the input system but must change the transformation itself to produce the proper contractions of muscles as output.[4]
Volume transmission[edit]
Neurotransmitter systems are systems of neurons in the brain expressing certain types of neurotransmitters, and thus form distinct systems. Activation of the system causes effects in large volumes of the brain, called volume transmission. Volume transmission is the diffusion of neurotransmitters through the brain extracellular fluid released at points that may be remote from the target cells with the resulting activation of extrasynaptic receptors, and with a longer time course than for transmission at a single synapse.[5] Such prolonged transmitter action is called tonic transmission, in contrast to the phasic transmission that occurs rapidly at single synapses.[6]
Neurotransmitter systems[edit]
The major neurotransmitter systems are the noradrenaline (norepinephrine) system, the dopamine system, the serotonin system and the cholinergic system. Drugs targeting the neurotransmitter of such systems affects the whole system, and explains the mode of action of many drugs.
Most other neurotransmitters, on the other hand, e.g. glutamate, GABA and glycine, are used very generally throughout the central nervous system.
Comparison[edit]
System | Origin[7] | Targets[7] | Effects[7] |
---|---|---|---|
Noradrenaline system | Locus coeruleus | Adrenergic receptors in:
|
|
Lateral tegmental field |
| ||
Dopamine system | Dopamine pathways:
| Dopamine receptors at pathway terminations. |
|
Serotonin system | caudal dorsal raphe nucleus | Serotonin receptors in:
|
|
rostral dorsal raphe nucleus | Serotonin receptors in:
| ||
Cholinergic system | Pedunculopontine nucleus and dorsolateral tegmental nuclei (pontomesencephalotegmental complex) | (mainly) M1 receptors in:
|
|
basal optic nucleus of Meynert | (mainly) M1 receptors in:
| ||
medial septal nucleus | (mainly) M1 receptors in:
|
Noradrenaline system[edit]
The noradrenaline system consists of just 1500 neurons on each side of the brain, primarily in the locus coeruleus. This is diminutive compared to the more than 100 billion neurons in the brain. As with dopaminergic neurons in the substantia nigra, neurons in the locus coeruleus tend to be melanin-pigmented. Noradrenaline is released from the neurons, and acts on adrenergic receptors. Noradrenaline is often released steadily so that it can prepare the supporting glial cells for calibrated responses. Despite containing a relatively small number of neurons, when activated, the noradrenaline system plays major roles in the brain including involvement in suppression of the neuroinflammatory response, stimulation of neuronal plasticity through LTP, regulation of glutamate uptake by astrocytes and LTD, and consolidation of memory.[10]
Dopamine system[edit]
The dopamine or dopaminergic system consists of several pathways, originating from the ventral tegmentum or substantia nigra as examples. It acts on dopamine receptors.
Parkinson's disease is at least in part related to dropping out of dopaminergic cells in deep-brain nuclei, primarily the melanin-pigmented neurons in the substantia nigra but secondarily the noradrenergic neurons of the locus coeruleus. Treatments potentiating the effect of dopamine precursors have been proposed and effected, with moderate success.
Dopamine pharmacology[edit]
Cocaine, for example, blocks the reuptake of dopamine, leaving these neurotransmitters in the synaptic gap longer.
AMPT prevents the conversion of tyrosine to L-DOPA, the precursor to dopamine; reserpine prevents dopamine storage within vesicles; and deprenyl inhibits monoamine oxidase (MAO)-B and thus increases dopamine levels.
Serotonin system[edit]
The serotonin created by the brain comprises around 10% of total body serotonin. The majority (80-90%) is found in the gastrointestinal (GI) tract.[11][12] It travels around the brain along the medial forebrain bundle and acts on serotonin receptors. In the peripheral nervous system (such as in the gut wall) serotonin regulates vascular tone.
Serotonin pharmacology[edit]
Selective serotonin reuptake inhibitors (SSRIs) such as Prozac (fluoxetine) are widely used antidepressants that specifically block the reuptake of serotonin with less effect on other transmitters.[13][14][15]
Tricyclic antidepressants also block reuptake of biogenic amines from the synapse, but may primarily effect serotonin or norepinephrine or both. They typically take 4 to 6 weeks to alleviate any symptoms of depression. They are considered to have immediate and long-term effects.[13][15][16]
Monoamine oxidase inhibitors allow reuptake of biogenic amine neurotransmitters from the synapse, but inhibit an enzyme which normally destroys (metabolizes) some of the transmitters after their reuptake. More of the neurotransmitters (especially serotonin, noradrenaline and dopamine) are available for release into synapses. MAOIs take several weeks to alleviate the symptoms of depression.[13][15][17][18]
Although changes in neurochemistry are found immediately after taking these antidepressants, symptoms may not begin to improve until several weeks after administration. Increased transmitter levels in the synapse alone does not relieve the depression or anxiety.[13][15][18]
Cholinergic system[edit]
The cholinergic system consists of projection neurons from the pedunculopontine nucleus, laterodorsal tegmental nucleus, and basal forebrain and interneurons from the striatum and nucleus accumbens. It is not yet clear whether acetylcholine as a neuromodulator acts through volume transmission or classical synaptic transmission, as there is evidence to support both theories. Acetylcholine binds to both metabotropic muscarinic receptors (mAChR) and the ionotropic nicotinic receptors (nAChR). The cholinergic system has been found to be involved in responding to cues related to the reward pathway, enhancing signal detection and sensory attention, regulating homeostasis, mediating the stress response, and encoding the formation of memories.[19][20]
GABA[edit]
Gamma-aminobutyric acid (GABA) has an inhibitory effect on brain and spinal cord activity.[13]
Neuropeptides[edit]
Opioid peptides – a large family of endogenous neuropeptides that are widely distributed throughout the central and peripheral nervous system. Opiate drugs such as heroin and morphine act at the receptors of these neurotransmitters.[13][21]
- Endorphins
- Enkephalins
- Dynorphins
- Oxytocin
- Substance P
Other uses[edit]
Neuromodulation also refers to an emerging class of medical therapies that target the nervous system for restoration of function (such as in cochlear implants), relief of pain, or control of symptoms, such as tremor seen in movement disorders like Parkinson's disease. The therapies consist primarily of targeted electrical stimulation, or infusion of medications into the cerebrospinal fluid using intrathecal drug delivery, such as baclofen for spasticity. Electrical stimulation devices include deep brain stimulation systems (DBS), colloquially referred to as "brain pacemakers", spinal cord stimulators (SCS) and vagus nerve stimulators (VNS), which are implanted using minimally invasive procedures, or transcutaneous electrical nerve stimulation devices, which are fully external, among others.[22]
See also[edit]
- 5-HT2c receptor agonist
- Natural neuroactive substance
References[edit]
^ Scheler, G; Fellous JM (2001). "Dopamine modulation of prefrontal delay activity-reverberatory activity and sharpness of tuning curves". Neurocomputing. 38-40: 1549–1556. arXiv:1608.04540. doi:10.1016/S0925-2312(01)00559-8..mw-parser-output cite.citationfont-style:inherit.mw-parser-output qquotes:"""""""'""'".mw-parser-output code.cs1-codecolor:inherit;background:inherit;border:inherit;padding:inherit.mw-parser-output .cs1-lock-free abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-lock-subscription abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registrationcolor:#555.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration spanborder-bottom:1px dotted;cursor:help.mw-parser-output .cs1-hidden-errordisplay:none;font-size:100%.mw-parser-output .cs1-visible-errorfont-size:100%.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-formatfont-size:95%.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-leftpadding-left:0.2em.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-rightpadding-right:0.2em
^ Procyk, E; Goldman-Rakic P (2006). "Modulation of dorsolateral prefrontal delay activity during self-organized behavior". J Neurosci. 26 (44): 11313–23. doi:10.1523/JNEUROSCI.2157-06.2006. PMID 17079659.
^ Conlay, L. A.; Sabounjian, L. A.; Wurtman, R. J. (1992). "Exercise and neuromodulators: Choline and acetylcholine in marathon runners". International Journal of Sports Medicine. 13 Suppl 1: S141–2. doi:10.1055/s-2007-1024619. PMID 1483754.
^ ab Stern, E; Fort TJ; Millier MW; Peskin CS; Brezina V (2007). "Decoding modulation of the neuromuscular transform". Neurocomputing. 70 (6954): 1753–1758. doi:10.1016/j.neucom.2006.10.117. PMC 2745187. PMID 19763188.
^ Castañeda-Hernández GC, Bach-y-Rita P (August 2003). "Volume transmission and pain perception". ScientificWorldJournal. 3: 677–83. doi:10.1100/tsw.2003.53. PMC 5974734. PMID 12920309.
^ Dreyer JK, Herrik KF, Berg RW, Hounsgaard JD (October 2010). "Influence of phasic and tonic dopamine release on receptor activation". J. Neurosci. 30 (42): 14273–83. doi:10.1523/JNEUROSCI.1894-10.2010. PMID 20962248.
^ abc Unless else specified in boxes, then ref is: Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. pp. 474 for noradrenaline system, page 476 for dopamine system, page 480 for serotonin system and page 483 for cholinergic system. ISBN 0-443-07145-4.
^ abcdefg Woolf NJ, Butcher LL (1989). "Cholinergic systems in the rat brain: IV. Descending projections of the pontomesencephalic tegmentum". Brain Res. Bull. 23 (6): 519–40. doi:10.1016/0361-9230(89)90197-4. PMID 2611694.
^ abcd Woolf NJ, Butcher LL (1986). "Cholinergic systems in the rat brain: III. Projections from the pontomesencephalic tegmentum to the thalamus, tectum, basal ganglia, and basal forebrain". Brain Res. Bull. 16 (5): 603–37. doi:10.1016/0361-9230(86)90134-6. PMID 3742247.
^ O'Donnell J, Zeppenfeld D, McConnell E, Pena S, Nedergaard M (November 2012). "Norepinephrine: a neuromodulator that boosts the function of multiple cell types to optimize CNS performance". Neurochem. Res. 37 (11): 2496–512. doi:10.1007/s11064-012-0818-x. PMC 3548657. PMID 22717696.
^ McIntosh, James. "What is serotonin? What does serotonin do?". Medical News Today. Medical News Today. Retrieved 12 April 2015.
^ Berger M, Gray JA, Roth BL (2009). "The expanded biology of serotonin". Annu. Rev. Med. 60: 355–66. doi:10.1146/annurev.med.60.042307.110802. PMC 5864293. PMID 19630576.
^ abcdef Kandel, Eric R (1991). Principles of Neural Science. East Norwalk, Connecticut: Appleton & Lang. pp. 872–873. ISBN 0-8385-8034-3.
^ "Depression Medication: Antidepressants, SSRIs, Antidepressants, SNRIs, Antidepressants, TCAs, Antidepressants, MAO Inhibitors, Augmenting Agents, Serotonin-Dopamine Activity Modulators, Antidepressants, Other, Stimulants, Thyroid Products, Neurology & Psychiatry, Herbals". emedicine.medscape.com. Retrieved 7 November 2016.
^ abcd Coryell, William (2016). "Drug Treatment of Depression". In Porter, Robert S. The Merck Manual (19 ed.). Whitehouse Station, N.J.: Merck. ISBN 978-0-911910-19-3.
^ "Drug Treatment of Depression". Merck Manuals Professional Edition. Retrieved 7 November 2016.
^ Bender, KJ; Walker, SE (8 October 2012). "Irreversible Monoamine Oxidase Inhibitors Revisited". Psychiatric Times. Retrieved 7 November 2016.
^ ab Wimbiscus, Molly; Kostenko, Olga; Malone, Donald (1 December 2010). "MAO inhibitors: risks, benefits, and lore". Cleveland Clinic Journal of Medicine. 77 (12): 859–882. doi:10.3949/ccjm.77a.09103. ISSN 1939-2869. PMID 21147941.
^ Picciotto MR, Higley MJ, Mineur YS (October 2012). "Acetylcholine as a neuromodulator: cholinergic signaling shapes nervous system function and behavior". Neuron. 76 (1): 116–29. doi:10.1016/j.neuron.2012.08.036. PMC 3466476. PMID 23040810.
^ Hasselmo ME, Sarter M (January 2011). "Modes and models of forebrain cholinergic neuromodulation of cognition". Neuropsychopharmacology. 36 (1): 52–73. doi:10.1038/npp.2010.104. PMC 2992803. PMID 20668433.
^ Froehlich, J. C. (1 January 1997). "Opioid peptides" (PDF). Alcohol Health and Research World. 21 (2): 132–136. ISSN 0090-838X. PMID 15704349.
^ Krames, Elliot S.; Peckham, P. Hunter; Rezai, Ali R., eds. (2009). Neuromodulation, Vol. 1-2. Academic Press. pp. 1–1200. ISBN 978-0-12-374248-3. Retrieved 6 September 2012.
External links[edit]
- North American Neuromodulation Society
- Neuromodulation and Neural Plasticity
- International Neuromodulation Society
- Scolarpedia article on neuromodulation
Categories:
- Neurochemistry
- Neurophysiology
(window.RLQ=window.RLQ||).push(function()mw.config.set("wgPageParseReport":"limitreport":"cputime":"0.720","walltime":"0.892","ppvisitednodes":"value":2847,"limit":1000000,"ppgeneratednodes":"value":0,"limit":1500000,"postexpandincludesize":"value":350280,"limit":2097152,"templateargumentsize":"value":710,"limit":2097152,"expansiondepth":"value":12,"limit":40,"expensivefunctioncount":"value":6,"limit":500,"unstrip-depth":"value":1,"limit":20,"unstrip-size":"value":69926,"limit":5000000,"entityaccesscount":"value":4,"limit":400,"timingprofile":["100.00% 603.921 1 -total"," 46.89% 283.162 1 Template:Reflist"," 35.62% 215.109 36 Template:Navbox"," 31.66% 191.210 14 Template:Cite_journal"," 8.62% 52.032 1 Template:Clarify"," 8.00% 48.332 1 Template:Fix-span"," 7.52% 45.421 1 Template:About"," 4.78% 28.864 1 Template:Neuromodulation"," 4.50% 27.163 1 Template:Telencephalon"," 4.06% 24.532 4 Template:Cite_book"],"scribunto":"limitreport-timeusage":"value":"0.310","limit":"10.000","limitreport-memusage":"value":5924326,"limit":52428800,"cachereport":"origin":"mw1257","timestamp":"20181218121529","ttl":1900800,"transientcontent":false););"@context":"https://schema.org","@type":"Article","name":"Neuromodulation","url":"https://en.wikipedia.org/wiki/Neuromodulation","sameAs":"http://www.wikidata.org/entity/Q905905","mainEntity":"http://www.wikidata.org/entity/Q905905","author":"@type":"Organization","name":"Contributors to Wikimedia projects","publisher":"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":"@type":"ImageObject","url":"https://www.wikimedia.org/static/images/wmf-hor-googpub.png","datePublished":"2006-03-20T21:05:52Z","dateModified":"2018-09-27T14:05:43Z"(window.RLQ=window.RLQ||).push(function()mw.config.set("wgBackendResponseTime":539,"wgHostname":"mw1242"););