Editing Neocortex (section)

===Layers===
[[File:Layers of the neocortex.png|thumb|555x555px|Neurons form distinct layers in mouse visual cortex.  Layer II/III (green), Layer IV (purple), Layer V (red), Layer VI (yellow). 3D reconstructions from the MICrONS cubic millimeter. ]]
The neocortex contains both excitatory (~80%) and inhibitory (~20%) [[neurons]], named for their effect on other neurons.<ref name="Noback; Strominger; Demarest; Ruggiero 2005">{{cite book|vauthors=Noback CR, Strominger NL, Demarest RJ, Ruggiero DA|title=The Human Nervous System: Structure and Function|date=2005|publisher=Humana Press|location=Totowa, NJ|isbn=1-59259-730-0|edition=Sixth}}</ref> The human neocortex consists of hundreds of different types of cells.<ref>{{Cite journal |last1=Berg |first1=Jim |last2=Sorensen |first2=Staci A. |last3=Ting |first3=Jonathan T. |last4=Miller |first4=Jeremy A. |last5=Chartrand |first5=Thomas |last6=Buchin |first6=Anatoly |last7=Bakken |first7=Trygve E. |last8=Budzillo |first8=Agata |last9=Dee |first9=Nick |last10=Ding |first10=Song-Lin |last11=Gouwens |first11=Nathan W. |last12=Hodge |first12=Rebecca D. |last13=Kalmbach |first13=Brian |last14=Lee |first14=Changkyu |last15=Lee |first15=Brian R. |date=October 2021 |title=Human neocortical expansion involves glutamatergic neuron diversification |journal=Nature |language=en |volume=598 |issue=7879 |pages=151–158 |doi=10.1038/s41586-021-03813-8 |pmid=34616067 |pmc=8494638 |issn=1476-4687|doi-access=free }}</ref> The structure of the neocortex is relatively uniform (hence the alternative names "iso-" and "homotypic" cortex), consisting of six horizontal layers segregated principally by [[cell (biology)|cell]] type and [[neuron]]al connections.<ref>{{Cite book|title = How to Create a Mind: The Secret of Human Thought Revealed|last = Kurzweil|first = Ray | name-list-style = vanc |publisher = Viking Penguin|year = 2012|isbn = 978-0670025299|location = New York|pages = 36}}</ref> However, there are many exceptions to this uniformity; for example, layer IV is small or missing in the [[motor cortex|primary motor cortex]]. There is some canonical circuitry within the cortex; for example, [[pyramidal neurons]] in the upper layers II and III project their [[axons]] to other areas of neocortex, while those in the deeper layers V and VI often project out of the cortex, e.g. to the [[thalamus]], [[brainstem]], and [[spinal cord]]. Neurons in layer IV receive the majority of the [[synapse|synaptic connections]] from outside the cortex (mostly from thalamus), and themselves make short-range, local connections to other cortical layers.<ref name="Noback; Strominger; Demarest; Ruggiero 2005"/> Thus, layer IV is the main recipient of incoming sensory information and distributes it to the other layers for further processing.