Editing Cerebral cortex (section)

====Layer I====
{{See also|Core-matrix theory of thalamus}}
Layer I is the '''molecular layer''', and contains few scattered neurons, including [[GABAergic]] [[rosehip neuron]]s.<ref name="Allen">{{cite web |title=Scientists identify a new kind of human brain cell |url=https://www.alleninstitute.org/what-we-do/brain-science/news-press/articles/scientists-identify-new-kind-human-brain-cell |website=Allen Institute |date=27 August 2018}}</ref> Layer I consists largely of extensions of apical [[dendrite|dendritic]] tufts of [[pyramidal cell|pyramidal neurons]] and horizontally oriented axons, as well as [[glial cells]].<ref name="Shipp_2007">{{cite journal | vauthors = Shipp S | title = Structure and function of the cerebral cortex | journal = Current Biology | volume = 17 | issue = 12 | pages = R443–R449 | date = June 2007 | pmid = 17580069 | pmc = 1870400 | doi = 10.1016/j.cub.2007.03.044 | bibcode = 2007CBio...17.R443S }}</ref> During development, [[Cajal–Retzius cell]]s<ref>{{cite journal | vauthors = Meyer G, Goffinet AM, Fairén A | title = What is a Cajal-Retzius cell? A reassessment of a classical cell type based on recent observations in the developing neocortex | journal = Cerebral Cortex | volume = 9 | issue = 8 | pages = 765–775 | date = December 1999 | pmid = 10600995 | doi = 10.1093/cercor/9.8.765 | doi-access =  }}</ref> and subpial granular layer cells<ref>{{cite journal | vauthors = Judaš M, Pletikos M |title=The discovery of the subpial granular layer in the human cerebral cortex |journal=Translational Neuroscience |date=2010 |volume=1 |issue=3 |pages=255–260 |doi=10.2478/v10134-010-0037-4 |s2cid=143409890|doi-access=free }}</ref> are present in this layer. Also, some spiny [[stellate cells]] can be found here. Inputs to the apical tufts are thought to be crucial for the ''feedback'' interactions in the cerebral cortex involved in associative learning and attention.<ref>{{cite journal | vauthors = Gilbert CD, Sigman M | title = Brain states: top-down influences in sensory processing | journal = Neuron | volume = 54 | issue = 5 | pages = 677–696 | date = June 2007 | pmid = 17553419 | doi = 10.1016/j.neuron.2007.05.019 | hdl-access = free | doi-access = free | hdl = 11336/67502 }}</ref>

While it was once thought that the input to layer I came from the cortex itself,<ref>{{cite journal | vauthors = Cauller L | title = Layer I of primary sensory neocortex: where top-down converges upon bottom-up | journal = Behavioural Brain Research | volume = 71 | issue = 1–2 | pages = 163–170 | date = November 1995 | pmid = 8747184 | doi = 10.1016/0166-4328(95)00032-1 | s2cid = 4015532 }}</ref> it is now known that layer I across the cerebral cortex receives substantial input from ''matrix'' or M-type thalamus cells,<ref>{{cite journal | vauthors = Rubio-Garrido P, Pérez-de-Manzo F, Porrero C, Galazo MJ, Clascá F | title = Thalamic input to distal apical dendrites in neocortical layer 1 is massive and highly convergent | journal = Cerebral Cortex | volume = 19 | issue = 10 | pages = 2380–2395 | date = October 2009 | pmid = 19188274 | doi = 10.1093/cercor/bhn259 | doi-access = free }}</ref> as opposed to ''core'' or C-type that go to layer IV.<ref name="Jones">{{cite journal | vauthors = Jones EG | title = Viewpoint: the core and matrix of thalamic organization | journal = Neuroscience | volume = 85 | issue = 2 | pages = 331–345 | date = July 1998 | pmid = 9622234 | doi = 10.1016/S0306-4522(97)00581-2 | s2cid = 17846130 }}</ref>

It is thought that layer I serves as a central hub for collecting and processing widespread information. It integrates ascending sensory inputs with top-down expectations, regulating how sensory perceptions align with anticipated outcomes. Further, layer I sorts, directs, and combines excitatory inputs, integrating them with neuromodulatory signals. Inhibitory interneurons, both within layer I and from other cortical layers, gate these signals. Together, these interactions dynamically calibrate information flow throughout the neocortex, shaping perceptions and experiences.<ref name="s309">{{cite journal | vauthors = Huang S, Wu SJ, Sansone G, Ibrahim LA, Fishell G | title = Layer 1 neocortex: Gating and integrating multidimensional signals | journal = Neuron | volume = 112 | issue = 2 | pages = 184–200 | date = January 2024 | pmid = 37913772 | doi = 10.1016/j.neuron.2023.09.041 | pmc = 11180419 }}</ref>