Editing Pyramidal cell (section)

==Signaling==

Like dendrites in most other neurons, the dendrites are generally the input areas of the neuron, while the axon is the neuron's output. Both axons and dendrites are highly branched. The large amount of branching allows the neuron to send and receive signals to and from many different neurons.

Pyramidal neurons, like other neurons, have numerous [[voltage-gated ion channel]]s. In pyramidal cells, there is an abundance of Na<sup>+</sup>, Ca<sup>2+</sup>, and K<sup>+</sup> channels in the dendrites, and some channels in the soma.<ref name="Spruston2008">{{cite journal | vauthors = Spruston N | title = Pyramidal neurons: dendritic structure and synaptic integration | journal = Nature Reviews. Neuroscience | volume = 9 | issue = 3 | pages = 206–221 | date = March 2008 | pmid = 18270515 | doi = 10.1038/nrn2286 | s2cid = 1142249 }}</ref><ref name="Georgiev2020">{{cite journal | vauthors = Georgiev DD, Kolev SK, Cohen E, Glazebrook JF | title = Computational capacity of pyramidal neurons in the cerebral cortex | journal = Brain Research | volume = 1748 | pages = 147069 | date = December 2020 | pmid = 32858030 | doi = 10.1016/j.brainres.2020.147069 | arxiv = 2009.10615 | s2cid = 221277603 }}</ref> Ion channels within pyramidal cell dendrites have different properties from the same ion channel type within the pyramidal cell soma.<ref name="Golding2005">{{cite journal | vauthors = Golding NL, Mickus TJ, Katz Y, Kath WL, Spruston N | title = Factors mediating powerful voltage attenuation along CA1 pyramidal neuron dendrites | journal = The Journal of Physiology | volume = 568 | issue = Pt 1 | pages = 69–82 | date = October 2005 | pmid = 16002454 | pmc = 1474764 | doi = 10.1113/jphysiol.2005.086793 }}</ref><ref name="Remy2010">{{cite journal | vauthors = Remy S, Beck H, Yaari Y | title = Plasticity of voltage-gated ion channels in pyramidal cell dendrites | journal = Current Opinion in Neurobiology | volume = 20 | issue = 4 | pages = 503–509 | date = August 2010 | pmid = 20691582 | doi = 10.1016/j.conb.2010.06.006 | s2cid = 4713853 }}</ref> Voltage-gated Ca<sup>2+</sup> channels in pyramidal cell dendrites are activated by subthreshold [[Excitatory postsynaptic potential|EPSP]]s and by [[Neural backpropagation|back-propagating]] action potentials. The extent of back-propagation of action potentials within pyramidal dendrites depends upon the K<sup>+</sup> channels. K<sup>+</sup> channels in pyramidal cell dendrites provide a mechanism for controlling the amplitude of action potentials.<ref name = "Magee">{{cite journal | vauthors = Magee J, Hoffman D, Colbert C, Johnston D | title = Electrical and calcium signaling in dendrites of hippocampal pyramidal neurons | journal = Annual Review of Physiology | volume = 60 | issue = 1 | pages = 327–346 | year = 1998 | pmid = 9558467 | doi = 10.1146/annurev.physiol.60.1.327 }}</ref>

The ability of pyramidal neurons to integrate information depends on the number and distribution of the synaptic inputs they receive. A single pyramidal cell receives about 30,000 excitatory inputs and 1700 inhibitory ([[IPSP]]s) inputs. Excitatory (EPSPs) inputs terminate exclusively on the dendritic spines, while inhibitory (IPSPs) inputs terminate on dendritic shafts, the soma, and even the axon. Pyramidal neurons can be excited by the [[neurotransmitter]] [[glutamate]],<ref name="Megias" /><ref>{{Citation|last1=Wong|first1=R. K. S.|title=NETWORKS {{!}} Cellular Properties and Synaptic Connectivity of CA3 Pyramidal Cells: Mechanisms for Epileptic Synchronization and Epileptogenesis|date=2009-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780123739612002150|encyclopedia=Encyclopedia of Basic Epilepsy Research|pages=815–819|editor-last=Schwartzkroin|editor-first=Philip A.|place=Oxford|publisher=Academic Press|language=en|doi=10.1016/b978-012373961-2.00215-0|isbn=978-0-12-373961-2|access-date=2020-11-18|last2=Traub|first2=R. D.|url-access=subscription}}</ref> and inhibited by the neurotransmitter [[GABA]].<ref name = "Megias" />
[[File:Layer_V_Pyramidal_cell_from_mouse_visual_cortex.png|thumb|Synaptic inputs to a Layer V Pyramidal cell in the mouse visual cortex. Each point represents one of >&nbsp;11,000 post-synaptic sites on this neuron.]]

===Firing classifications===
Pyramidal neurons have been classified into different subclasses based upon their firing responses to 400-1000 millisecond current pulses. These classification are RSad, RSna, and IB neurons.

====RSad====
RSad pyramidal neurons, or adapting regular [[Biological neuron model|spiking neuron]]s, fire with individual [[action potential]]s (APs), which are followed by a [[Hyperpolarization (biology)|hyperpolarizing]] afterpotential. The afterpotential increases in duration which creates [[Action potential|spike frequency]] [[Neural adaptation|adaptation]] (SFA) in the neuron.<ref name = "Frances">{{cite journal | vauthors = Franceschetti S, Sancini G, Panzica F, Radici C, Avanzini G | title = Postnatal differentiation of firing properties and morphological characteristics in layer V pyramidal neurons of the sensorimotor cortex | journal = Neuroscience | volume = 83 | issue = 4 | pages = 1013–1024 | date = April 1998 | pmid = 9502243 | doi = 10.1016/S0306-4522(97)00463-6 | s2cid = 6986307 }}</ref>

====RSna====
RSna pyramidal neurons, or non-adapting regular spiking neurons, fire a train of action potentials after a pulse. These neurons show no signs of adaptation.<ref name="Frances" />

====IB====
IB pyramidal neurons, or intrinsically bursting neurons, respond to [[Threshold potential|threshold]] pulses with a burst of two to five rapid action potentials. IB pyramidal neurons show no adaptation.<ref name="Frances" />

=== Molecular classifications ===
There are several studies showing that morphological and electric pyramidal cells properties could be deduced from gene expression measured by [[single cell sequencing]].<ref name="Berg 151–158">{{cite journal | vauthors = Berg J, Sorensen SA, Ting JT, Miller JA, Chartrand T, Buchin A, Bakken TE, Budzillo A, Dee N, Ding SL, Gouwens NW, Hodge RD, Kalmbach B, Lee C, Lee BR, Alfiler L, Baker K, Barkan E, Beller A, Berry K, Bertagnolli D, Bickley K, Bomben J, Braun T, Brouner K, Casper T, Chong P, Crichton K, Dalley R, de Frates R, Desta T, Lee SD, D'Orazi F, Dotson N, Egdorf T, Enstrom R, Farrell C, Feng D, Fong O, Furdan S, Galakhova AA, Gamlin C, Gary A, Glandon A, Goldy J, Gorham M, Goriounova NA, Gratiy S, Graybuck L, Gu H, Hadley K, Hansen N, Heistek TS, Henry AM, Heyer DB, Hill D, Hill C, Hupp M, Jarsky T, Kebede S, Keene L, Kim L, Kim MH, Kroll M, Latimer C, Levi BP, Link KE, Mallory M, Mann R, Marshall D, Maxwell M, McGraw M, McMillen D, Melief E, Mertens EJ, Mezei L, Mihut N, Mok S, Molnar G, Mukora A, Ng L, Ngo K, Nicovich PR, Nyhus J, Olah G, Oldre A, Omstead V, Ozsvar A, Park D, Peng H, Pham T, Pom CA, Potekhina L, Rajanbabu R, Ransford S, Reid D, Rimorin C, Ruiz A, Sandman D, Sulc J, Sunkin SM, Szafer A, Szemenyei V, Thomsen ER, Tieu M, Torkelson A, Trinh J, Tung H, Wakeman W, Waleboer F, Ward K, Wilbers R, Williams G, Yao Z, Yoon JG, Anastassiou C, Arkhipov A, Barzo P, Bernard A, Cobbs C, de Witt Hamer PC, Ellenbogen RG, Esposito L, Ferreira M, Gwinn RP, Hawrylycz MJ, Hof PR, Idema S, Jones AR, Keene CD, Ko AL, Murphy GJ, Ng L, Ojemann JG, Patel AP, Phillips JW, Silbergeld DL, Smith K, Tasic B, Yuste R, Segev I, de Kock CP, Mansvelder HD, Tamas G, Zeng H, Koch C, Lein ES | display-authors = 6 | title = Human neocortical expansion involves glutamatergic neuron diversification | journal = Nature | volume = 598 | issue = 7879 | pages = 151–158 | date = October 2021 | pmid = 34616067 | pmc = 8494638 | doi = 10.1038/s41586-021-03813-8 | bibcode = 2021Natur.598..151B }}</ref> Several studies are proposing that single cell classifications in mouse<ref>{{cite journal | vauthors = Gouwens NW, Sorensen SA, Berg J, Lee C, Jarsky T, Ting J, Sunkin SM, Feng D, Anastassiou CA, Barkan E, Bickley K, Blesie N, Braun T, Brouner K, Budzillo A, Caldejon S, Casper T, Castelli D, Chong P, Crichton K, Cuhaciyan C, Daigle TL, Dalley R, Dee N, Desta T, Ding SL, Dingman S, Doperalski A, Dotson N, Egdorf T, Fisher M, de Frates RA, Garren E, Garwood M, Gary A, Gaudreault N, Godfrey K, Gorham M, Gu H, Habel C, Hadley K, Harrington J, Harris JA, Henry A, Hill D, Josephsen S, Kebede S, Kim L, Kroll M, Lee B, Lemon T, Link KE, Liu X, Long B, Mann R, McGraw M, Mihalas S, Mukora A, Murphy GJ, Ng L, Ngo K, Nguyen TN, Nicovich PR, Oldre A, Park D, Parry S, Perkins J, Potekhina L, Reid D, Robertson M, Sandman D, Schroedter M, Slaughterbeck C, Soler-Llavina G, Sulc J, Szafer A, Tasic B, Taskin N, Teeter C, Thatra N, Tung H, Wakeman W, Williams G, Young R, Zhou Z, Farrell C, Peng H, Hawrylycz MJ, Lein E, Ng L, Arkhipov A, Bernard A, Phillips JW, Zeng H, Koch C | display-authors = 6 | title = Classification of electrophysiological and morphological neuron types in the mouse visual cortex | journal = Nature Neuroscience | volume = 22 | issue = 7 | pages = 1182–1195 | date = July 2019 | pmid = 31209381 | pmc = 8078853 | doi = 10.1038/s41593-019-0417-0 }}</ref> and human<ref>{{cite journal | vauthors = Bakken TE, Jorstad NL, Hu Q, Lake BB, Tian W, Kalmbach BE, Crow M, Hodge RD, Krienen FM, Sorensen SA, Eggermont J, Yao Z, Aevermann BD, Aldridge AI, Bartlett A, Bertagnolli D, Casper T, Castanon RG, Crichton K, Daigle TL, Dalley R, Dee N, Dembrow N, Diep D, Ding SL, Dong W, Fang R, Fischer S, Goldman M, Goldy J, Graybuck LT, Herb BR, Hou X, Kancherla J, Kroll M, Lathia K, van Lew B, Li YE, Liu CS, Liu H, Lucero JD, Mahurkar A, McMillen D, Miller JA, Moussa M, Nery JR, Nicovich PR, Niu SY, Orvis J, Osteen JK, Owen S, Palmer CR, Pham T, Plongthongkum N, Poirion O, Reed NM, Rimorin C, Rivkin A, Romanow WJ, Sedeño-Cortés AE, Siletti K, Somasundaram S, Sulc J, Tieu M, Torkelson A, Tung H, Wang X, Xie F, Yanny AM, Zhang R, Ament SA, Behrens MM, Bravo HC, Chun J, Dobin A, Gillis J, Hertzano R, Hof PR, Höllt T, Horwitz GD, Keene CD, Kharchenko PV, Ko AL, Lelieveldt BP, Luo C, Mukamel EA, Pinto-Duarte A, Preissl S, Regev A, Ren B, Scheuermann RH, Smith K, Spain WJ, White OR, Koch C, Hawrylycz M, Tasic B, Macosko EZ, McCarroll SA, Ting JT, Zeng H, Zhang K, Feng G, Ecker JR, Linnarsson S, Lein ES | display-authors = 6 | title = Comparative cellular analysis of motor cortex in human, marmoset and mouse | journal = Nature | volume = 598 | issue = 7879 | pages = 111–119 | date = October 2021 | pmid = 34616062 | pmc = 8494640 | doi = 10.1038/s41586-021-03465-8 | bibcode = 2021Natur.598..111B }}</ref> neurons based on gene expression could explain various neuronal properties . Neuronal types in these classifications are split into excitatory, inhibitory and hundreds of corresponding sub-types. For example, pyramidal cells of layer 2-3 in human are classified as FREM3 type<ref name="Berg 151–158"/> and often have a high amount of Ih-current<ref>{{cite journal | vauthors = Kalmbach BE, Buchin A, Long B, Close J, Nandi A, Miller JA, Bakken TE, Hodge RD, Chong P, de Frates R, Dai K, Maltzer Z, Nicovich PR, Keene CD, Silbergeld DL, Gwinn RP, Cobbs C, Ko AL, Ojemann JG, Koch C, Anastassiou CA, Lein ES, Ting JT | display-authors = 6 | title = h-Channels Contribute to Divergent Intrinsic Membrane Properties of Supragranular Pyramidal Neurons in Human versus Mouse Cerebral Cortex | journal = Neuron | volume = 100 | issue = 5 | pages = 1194–1208.e5 | date = December 2018 | pmid = 30392798 | pmc = 6447369 | doi = 10.1016/j.neuron.2018.10.012 | s2cid = 53218514 | doi-access = free }}</ref> generated by [[HCN channel|HCN-channel]].