|
==Anatomi==
[[Image:Gray706.png|thumb|200px|left|TransverseTransversalsnit sectionaf ofen afoldning cerebellari [[foliumlillehjernen (brain)|folium]].med (Purkinje Cellcelle angivelsen centralt labeledi attoppen centeraf topbilledet.)]]
[[Image:Cerebellum - biel - very high mag.jpg|thumb|left|Purkinje cells. [[Bielschowsky stain]].]]
Purkinje celler er nogle af de største celler i menneskehjenenmenneskehjernen (med [[Betz celle]]r som de største)<ref name="Purves" >{{cite book | author = Purves, Dale, George J. Augustine, David Fitzpatrick, William C. Hall, Anthony-Samuel LaMantia, James O. McNamara, and Leonard E. White | title = Neuroscience. 4th ed. | publisher = Sinauer Associates | pages = 432–4 | year = 2008 | isbn = 978-0-87893-697-7}}</ref> med et indviklet og detaljeret dendrittræ, som er karakteriseret ved detet storestort antal af dendritiske fremskud (en: Spines). Purkinje cellerne forekommer i lillehjernens såkaldte [[Purkinje lag]]. Purkinje cellerne er placeret foran hinanden som [[domino]]brikker. Deres store dendritiske træ danner nærmest et todimensionelt netværk, hvor [[parallelfibre]]r fra de dybere lillehjernelag passerer. Parallelfibrene danner forholdvis svagere [[excitatorisk]]e (aktiverende) [[glutamat|glutaminerge]] [[synapse]]r med dendritfremskuddene på dendritttræet, hvorimod [[klatre fibre]]r fra [[nucleus olivarius inferior]] i [[medulla oblongata]] danner et kraftigt excitatorisk input til de [[proksimal]]e dendritter og cellelegemet. Parallelfibrer passerer [[ortogonal]]t gennem Purkinje cellernes dendrittræ med op til 200.000 parallelfibrer,<ref>{{cite journal|last=Tyrrell|first=T|coauthors=Willshaw, D|title=Cerebellar cortex: its simulation and the relevance of Marr's theory.|journal=Philosophical transactions of the Royal Society of London. Series B, Biological sciences|date=1992-05-29|volume=336|issue=1277|pages=239–57|pmid=1353267|doi=10.1098/rstb.1992.0059}}</ref> dannende et [[Granula-celle-Purkinje celle synapse]] med en enkel Purkinje celle. Hver Purkinje celle modtager ca. 500 klatrefibrersynapser som alle opstår fra en enkel klatrefibre<ref>{{cite journal|last=Wadiche|first=JI|coauthors=Jahr, CE|title=Multivesicular release at climbing fiber-Purkinje cell synapses|journal=Neuron|date=2001-10-25|volume=32|issue=2|pages=301–13|pmid=11683999|doi=10.1016/S0896-6273(01)00488-3}}</ref>. Både [[Kurvecelle]]r og [[Stellate celle]]r (lokaliseret i lillehjernens molekylærlag danner inhibitoriske (hæmmende) [[GABA]]erge input til Purkinje cellerne, med Kurveceller som synapser på Purkinje cellernes [[akson]]rod og stellate celler på dendritterne.
Purkinje celler sender inhibitoriske projektioner til de dybe lillehjerne kerner, og udgør derved det endelige output vedrørende motorisk koordination i lillehjernebarken.
Purkinje cells are aligned like [[domino]]s stacked one in front of the other. Their large dendritic arbors form nearly [[two-dimensional]] layers through which [[parallel fiber]]s from the deeper-layers pass. These parallel fibers make relatively weaker [[excitatory synapse|excitatory]] ([[glutamatergic]]) synapses to spines in the Purkinje cell dendrite, whereas [[climbing fibers]] originating from the [[inferior olivary nucleus]] in the [[medulla oblongata|medulla]] provide very powerful excitatory input to the proximal dendrites and cell soma. Parallel fibers pass [[orthogonal]]ly through the Purkinje neuron's dendritic arbor, with up to 200,000 parallel fibers<ref>{{cite journal|last=Tyrrell|first=T|coauthors=Willshaw, D|title=Cerebellar cortex: its simulation and the relevance of Marr's theory.|journal=Philosophical transactions of the Royal Society of London. Series B, Biological sciences|date=1992-05-29|volume=336|issue=1277|pages=239–57|pmid=1353267|doi=10.1098/rstb.1992.0059}}</ref> forming a [[Granule-cell-Purkinje-cell synapse]] with a single Purkinje cell. Each Purkinje cell receives ca 500 climbing fiber synapses, all originating from a single climbing fiber.<ref>{{cite journal|last=Wadiche|first=JI|coauthors=Jahr, CE|title=Multivesicular release at climbing fiber-Purkinje cell synapses|journal=Neuron|date=2001-10-25|volume=32|issue=2|pages=301–13|pmid=11683999|doi=10.1016/S0896-6273(01)00488-3}}</ref> Both basket and stellate cells (found in the cerebellar [[Cerebellum#Molecular Layer|molecular layer]]) provide [[inhibitory]] (GABAergic) input to the Purkinje cell, with basket cells synapsing on the Purkinje cell axon initial segment and stellate cells onto the dendrites.
Purkinje cells send inhibitory projections to the deep cerebellar nuclei, and constitute the sole output of all [[motor coordination]] in the cerebellar cortex.
== Elektrofysiologi ==
[[Image:CerebCircuit.png|thumb|right|200px|Microcircuitry of the cerebellum. [[Excitatory synapses]] are denoted by (+) and [[inhibitory synapses]] by (-).<BR>MF: [[Mossy fiber (cerebellum)|Mossy fiber]].<BR>DCN: [[Deep cerebellar nuclei]].<BR>IO: [[Inferior olivary nucleus|Inferior olive]].<BR>CF: [[Climbing fiber]].<BR>GC: [[Granule cell]].<BR>PF: [[Parallel fiber]].<BR>PC: Purkinje cell.<BR>GgC: [[Golgi cell]].<BR>SC: [[Stellate cell]].<BR>BC: [[Basket cell]].]]
| 