Wikipedia

Autapse

Anautapseis achemicalorelectrical synapsefrom aneurononto itself.[1][2]It can also be described as a synapse formed by theaxonof a neuron on its owndendrites,in vivoorin vitro.

History

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The term "autapse" was first coined in 1972 by Van der Loos and Glaser, who observed them in Golgi preparations of the rabbitoccipital cortexwhile originally conducting a quantitative analysis ofneocortexcircuitry.[3]Also in the 1970s, autapses have been described in dog and ratcerebral cortex,[4][5][6]monkeyneostriatum,[7]and catspinal cord.[8]

In 2000, they were first modeled as supporting persistence inrecurrent neural networks.[1]In 2004, they were modeled as demonstratingoscillatory behavior,which was absent in the same model neuron without autapse.[9]More specifically, the neuron oscillated between high firing rates and firing suppression, reflecting the spikeburstingbehavior typically found in cerebral neurons. In 2009, autapses were, for the first time, associated with sustained activation. This proposed a possible function for excitatory autapses within a neural circuit.[10]In 2014, electrical autapses were shown to generate stabletargetandspiral wavesin aneural model network.[11]This indicated that they played a significant role in stimulating and regulating the collective behavior of neurons in the network. In 2016, a model of resonance was offered.[12]

Autapses have been used to simulate "same cell" conditions to help researchers make quantitative comparisons, such as studying howN-methyl-D-aspartate receptor(NMDAR)antagonistsaffect synaptic versus extrasynaptic NMDARs.[13]

Formation

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Recently, it has been proposed that autapses could possibly form as a result of neuronal signal transmission blockage, such as in cases of axonal injury induced by poisoning or impeding ion channels.[14]Dendrites from thesomain addition to an auxiliary axon may develop to form an autapse to help remediate the neuron's signal transmission.

Structure and function

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Autapses can be eitherglutamate-releasing(excitatory) orGABA-releasing(inhibitory), just like their traditional synapse counterparts.[15]Similarly, autapses can be electrical or chemical by nature.[2]

Broadly speaking, negative feedback in autapses tends to inhibit excitable neurons whereas positive feedback can stimulate quiescent neurons.[16]

Although the stimulation of inhibitory autapses did not inducehyperpolarizinginhibitory post-synaptic potentialsininterneuronsoflayer Vof neocortical slices, they have been shown to impact excitability.[17]Upon using a GABA-antagonist to block autapses, the likelihood of an immediate subsequent seconddepolarizationstep increased following a first depolarization step. This suggests that autapses act by suppressing the second of two closely timed depolarization steps and therefore, they may provide feedback inhibition onto these cells. This mechanism may also potentially explainshunting inhibition.

In cell culture, autapses have been shown to contribute to the prolonged activation ofB31/B32 neurons,which significantly contribute food-response behavior inAplysia.[10]This suggests that autapses may play a role in mediating positive feedback. The B31/B32 autapse was unable to play a role in initiating the neuron's activity, although it is believed to have helped sustain the neuron's depolarized state. The extent to which autapses maintain depolarization remains unclear, particularly since other components of the neural circuit (i.e. B63 neurons) are also capable of providing strong synaptic input throughout the depolarization. Additionally, it has been suggested that autapses provide B31/B32 neurons with the ability to quicklyrepolarize.Bekkers (2009) has proposed that specifically blocking the contribution of autapses and then assessing the differences with or without blocked autapses could better illuminate the function of autapses.[18]

Hindmarsh–Rose(HR) model neurons have demonstratedchaotic,regularspiking,quiescent,andperiodicpatterns of burst firing without autapses.[19]Upon the introduction of an electrical autapse, the periodic state switches to the chaotic state and displays an alternating behavior that increases in frequency with a greater autaptic intensity and time delay. On the other hand, excitatory chemical autapses enhanced the overall chaotic state. The chaotic state was reduced and suppressed in the neurons with inhibitory chemical autapses. In HR model neurons without autapses, the pattern of firing altered from quiescent to periodic and then to chaotic asDC currentwas increased. Generally, HR model neurons with autapses have the ability to swap into any firing pattern, regardless of the prior firing pattern.

Location

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Neurons from several brain regions, such as the neocortex, substantia nigra, and hippocampus have been found to contain autapses.[3][20][21][22]

Autapses have been observed to be relatively more abundant in GABAergicbasketanddendrite-targeting cellsof the cat visual cortex compared to spinystellate,double bouquet,andpyramidal cells,suggesting that the degree of neuron self-innervation is cell-specific.[23]Additionally, dendrite-targeting cell autapses were, on average, further from the soma compared to basket cell autapses.

80% of layer Vpyramidal neuronsin developing rat neocortices contained autaptic connections, which were located more so onbasal dendritesand apicaloblique dendritesrather than mainapical dendrites.[24]The dendritic positions of synaptic connections of the same cell type were similar to those of autapses, suggesting that autaptic and synaptic networks share a common mechanism of formation.

Disease implications

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In the 1990s,paroxysmal depolarizing shift-typeinterictal epileptiformdischarges has been suggested to be primarily dependent on autaptic activity for solitary excitatory hippocampal rat neurons grown in microculture.[25]

More recently, in human neocortical tissues of patients withintractable epilepsy,the GABAergic output autapses offast-spiking(FS) neurons have been shown to have strongerasynchronous release(AR) compared to both non-epileptic tissue and other types of synapses involving FS neurons.[26]The study found similar results using a rat model as well. An increase in residual Ca2+ concentration in addition to the action potential amplitude in FS neurons was suggested to cause this increase in AR of epileptic tissue. Anti-epileptic drugs could potentially target this AR of GABA that seems to rampantly occur at FS neuron autapses.

Effects of drugs

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Using aglia-conditioned mediumto treat glia-free purified ratretinal ganglionmicrocultures has been shown to significantly increase the number of autapses per neuron compared to a control.[27]This suggests that glia-derived soluble,proteinase K-sensitive factors induce autapse formation in rat retinal ganglion cells.

References

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  1. ^abSeung, H. Sebastian; Lee, Daniel D.; Reis, Ben Y.; Tank, David W. (2000-09-01). "The Autapse: A Simple Illustration of Short-Term Analog Memory Storage by Tuned Synaptic Feedback".Journal of Computational Neuroscience.9(2): 171–185.doi:10.1023/A:1008971908649.ISSN0929-5313.PMID11030520.S2CID547421.
  2. ^abYilmaz, Ergin; Ozer, Mahmut; Baysal, Veli; Perc, Matjaž (2016-08-02)."Autapse-induced multiple coherence resonance in single neurons and neuronal networks".Scientific Reports.6(1): 30914.Bibcode:2016NatSR...630914Y.doi:10.1038/srep30914.ISSN2045-2322.PMC4969620.PMID27480120.
  3. ^abVan der Loos, H.; Glaser, E. M. (1972-12-24). "Autapses in neocortex cerebri: synapses between a pyramidal cell's axon and its own dendrites".Brain Research.48:355–360.doi:10.1016/0006-8993(72)90189-8.ISSN0006-8993.PMID4645210.
  4. ^Shkol’nik-Yarros, Ekaterina G. (1971).Neurons and Interneuronal Connections of the Central Visual System | SpringerLink.doi:10.1007/978-1-4684-0715-0.ISBN978-1-4684-0717-4.S2CID37317913.
  5. ^Preston, R.J.; Bishop, G.A.; Kitai, S.T. (1980-02-10). "Medium spiny neuron projection from the rat striatum: An intracellular horseradish peroxidase study".Brain Research.183(2): 253–263.doi:10.1016/0006-8993(80)90462-X.ISSN0006-8993.PMID7353139.S2CID1827091.
  6. ^Peters, A.; Proskauer, C. C. (April 1980). "Synaptic relationships between a multipolar stellate cell and a pyramidal neuron in the rat visual cortex. A combined Golgi-electron microscope study".Journal of Neurocytology.9(2): 163–183.doi:10.1007/bf01205156.ISSN0300-4864.PMID6160209.S2CID34203892.
  7. ^DiFiglia, M.; Pasik, P.; Pasik, T. (1976-09-17). "A Golgi study of neuronal types in the neostriatum of monkeys".Brain Research.114(2): 245–256.doi:10.1016/0006-8993(76)90669-7.ISSN0006-8993.PMID822916.S2CID40311354.
  8. ^Scheibel, M.E.; Scheibel, A.B. (1971). "Inhibition and the Renshaw Cell A Structural Critique; pp. 73–93".Brain, Behavior and Evolution.4(1): 73–93.doi:10.1159/000125425.ISSN0006-8977.
  9. ^Herrmann, Christoph S. (August 2004). "Autapse Turns Neuron Into Oscillator".International Journal of Bifurcation and Chaos.4(2): 623–633.Bibcode:2004IJBC...14..623H.doi:10.1142/S0218127404009338.
  10. ^abSaada, R.; Miller, N.; Hurwitz, I.; Susswein, A. J. (2009)."Autaptic muscarinic excitation underlies a plateau potential and persistent activity in a neuron of known behavioral function".Current Biology.19(6): 479–484.doi:10.1016/j.cub.2009.01.060.PMID19269179.S2CID15990017.
  11. ^Qin, H.; Ma, J.; Wang, C.; Chu, R. (2014). "Autapse-induced target wave, spiral wave in regular network of neurons".Science China Physics, Mechanics & Astronomy.57(10): 1918–1926.Bibcode:2014SCPMA..57.1918Q.doi:10.1007/s11433-014-5466-5.S2CID120661751.
  12. ^Yilmaz, E.; Ozer, M.; Baysal, V.; Perc, M. (2 August 2016)."Autapse-induced multiple coherence resonance in single neurons and neuronal networks".Scientific Reports.9:30914.Bibcode:2016NatSR...630914Y.doi:10.1038/srep30914.PMC4969620.PMID27480120.
  13. ^Xia, Peng; Chen, Huei-sheng Vincent; Zhang, Dongxian; Lipton, Stuart A. (2010-08-18)."Memantine Preferentially Blocks Extrasynaptic over Synaptic NMDA Receptor Currents in Hippocampal Autapses".Journal of Neuroscience.30(33): 11246–11250.doi:10.1523/JNEUROSCI.2488-10.2010.ISSN0270-6474.PMC2932667.PMID20720132.
  14. ^Wang, Chunni; Guo, Shengli; Xu, Ying; Ma, Jun; Tang, Jun; Alzahrani, Faris; Hobiny, Aatef (2017)."Formation of Autapse Connected to Neuron and Its Biological Function".Complexity.2017:1–9.doi:10.1155/2017/5436737.ISSN1076-2787.
  15. ^Ikeda, Kaori; Bekkers, John M. (2006-05-09)."Autapses".Current Biology.16(9): R308.Bibcode:2006CBio...16.R308I.doi:10.1016/j.cub.2006.03.085.ISSN0960-9822.PMID16682332.
  16. ^Qin, Huixin; Wu, Ying; Wang, Chunni; Ma, Jun (2015). "Emitting waves from defects in network with autapses".Communications in Nonlinear Science and Numerical Simulation.23(1–3): 164–174.Bibcode:2015CNSNS..23..164Q.doi:10.1016/j.cnsns.2014.11.008.
  17. ^Bacci, Alberto; Huguenard, John R.; Prince, David A. (2003-02-01)."Functional autaptic neurotransmission in fast-spiking interneurons: a novel form of feedback inhibition in the neocortex".The Journal of Neuroscience.23(3): 859–866.doi:10.1523/JNEUROSCI.23-03-00859.2003.ISSN1529-2401.PMC6741939.PMID12574414.
  18. ^Bekkers, John M. (2009)."Synaptic Transmission: Excitatory Autapses Find a Function?".Current Biology.19(7): R296–R298.Bibcode:2009CBio...19.R296B.doi:10.1016/j.cub.2009.02.010.PMID19368875.S2CID15821336.
  19. ^Wang, Hengtong; Ma, Jun; Chen, Yueling; Chen, Yong (2014). "Effect of an autapse on the firing pattern transition in a bursting neuron".Communications in Nonlinear Science and Numerical Simulation.19(9): 3242–3254.Bibcode:2014CNSNS..19.3242W.doi:10.1016/j.cnsns.2014.02.018.
  20. ^Park, Melburn R.; Lighthall, James W.; Kitai, Stephen T. (1980). "Recurrent inhibition in the rat neostriatum".Brain Research.194(2): 359–369.doi:10.1016/0006-8993(80)91217-2.PMID7388619.S2CID29451737.
  21. ^Karabelas, Athanasios B.; Purrura, Dominick P. (1980). "Evidence for autapses in the substantia nigra".Brain Research.200(2): 467–473.doi:10.1016/0006-8993(80)90935-x.PMID6158366.S2CID35517474.
  22. ^Cobb, S.R; Halasy, K; Vida, I; Nyı́ri, G; Tamás, G; Buhl, E.H; Somogyi, P (1997). "Synaptic effects of identified interneurons innervating both interneurons and pyramidal cells in the rat hippocampus".Neuroscience.79(3): 629–648.doi:10.1016/s0306-4522(97)00055-9.PMID9219929.S2CID15479304.
  23. ^Tamás, G.; Buhl, E. H.; Somogyi, P. (1997-08-15)."Massive autaptic self-innervation of GABAergic neurons in cat visual cortex".The Journal of Neuroscience.17(16): 6352–6364.doi:10.1523/JNEUROSCI.17-16-06352.1997.ISSN0270-6474.PMC6568358.PMID9236244.
  24. ^Lübke, J.; Markram, H.; Frotscher, M.; Sakmann, B. (1996-05-15)."Frequency and dendritic distribution of autapses established by layer 5 pyramidal neurons in the developing rat neocortex: comparison with synaptic innervation of adjacent neurons of the same class".The Journal of Neuroscience.16(10): 3209–3218.doi:10.1523/JNEUROSCI.16-10-03209.1996.ISSN0270-6474.PMC6579140.PMID8627359.
  25. ^Segal, M. M. (October 1994). "Endogenous bursts underlie seizurelike activity in solitary excitatory hippocampal neurons in microcultures".Journal of Neurophysiology.72(4): 1874–1884.doi:10.1152/jn.1994.72.4.1874.ISSN0022-3077.PMID7823106.
  26. ^Jiang, Man; Zhu, Jie; Liu, Yaping; Yang, Mingpo; Tian, Cuiping; Jiang, Shan; Wang, Yonghong; Guo, Hui; Wang, Kaiyan (2012-05-08)."Enhancement of Asynchronous Release from Fast-Spiking Interneuron in Human and Rat Epileptic Neocortex".PLOS Biology.10(5): e1001324.doi:10.1371/journal.pbio.1001324.ISSN1545-7885.PMC3348166.PMID22589699.
  27. ^Nägler, Karl; Mauch, Daniela H; Pfrieger, Frank W (2001-06-15)."Glia-derived signals induce synapse formation in neurones of the rat central nervous system".The Journal of Physiology.533(Pt 3): 665–679.doi:10.1111/j.1469-7793.2001.00665.x.ISSN0022-3751.PMC2278670.PMID11410625.
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