Editing Cortical column (section)

==Mammalian cerebral cortex==
{{Main|Cerebral cortex}}
The [[mammalian]] [[cerebral cortex]], the [[grey matter]] encapsulating the [[white matter]], is composed of [[Cerebral cortex#Laminar pattern|layers]]. The [[human]] cortex is between 2 and 3&nbsp;mm thick.<ref name="Saladin11">{{cite book |last1=Saladin |first1=Kenneth |title=Human anatomy |date=2011 |publisher=McGraw-Hill |isbn=9780071222075 |page=416 |edition=3rd}}</ref> The number of layers is the same in most mammals, but varies throughout the cortex. [[Neocortex#Anatomy|6 layers]] can be recognized in the neocortex, although many regions lack one or more layers. For example, fewer layers are present in the [[archipallium]] and the [[paleopallium]].<ref>{{cite book|author1=R Nieuwenhuys |author2=HJ Donkelaar |author3=C Nicholson |author4=WJAJ Smeets |author5=H Wicht |title=The central nervous system of vertebrates|year=1998|publisher=Springer|location=Berlin [u.a.]|isbn=978-3540560135}}</ref>

===Columnar functional organization===
The columnar functional organization, as originally framed by [[Vernon Mountcastle]],<ref name="Mountcastle1957" /> suggests that neurons that are horizontally more than 0.5&nbsp;mm (500&nbsp;μm) from each other do not have overlapping sensory receptive fields, and other experiments give similar results: 200–800&nbsp;μm.<ref name=":0" /><ref>{{cite journal |vauthors=Hubel DH, Wiesel TN, Stryker MP|title=Orientation columns in macaque monkey visual cortex demonstrated by the 2-deoxyglucose autoradiographic technique |journal=Nature |volume=269 |issue=5626 |pages=328–30 |date=September 1977  |pmid=409953|bibcode=1977Natur.269..328H |doi=10.1038/269328a0 |s2cid=4246375 }}</ref><ref>{{cite journal |author=Leise EM |title=Modular construction of nervous systems: a basic principle of design for invertebrates and vertebrates |journal=Brain Research. Brain Research Reviews |volume=15 |issue=1 |pages=1–23 |year=1990 |pmid=2194614 |doi=10.1016/0165-0173(90)90009-d|s2cid=4996690 |url=http://libres.uncg.edu/ir/uncg/f/E_Leise_Modular_1990.pdf }}</ref>  Various estimates suggest there are 50 to 100 [[cortical minicolumn]]s in a hypercolumn, each comprising around 80 neurons. Their role is best understood as 'functional units of information processing.'

An important distinction is that the columnar organization is functional by definition, and reflects the local connectivity of the cerebral cortex.  Connections "up" and "down" within the thickness of the cortex are much denser than connections that spread from side to side.