Editing Cerebral cortex (section)

== Function ==
[[File:Constudproc.png|thumb|Some functional areas of cortex]]

===Connections===
The cerebral cortex is connected to various subcortical structures such as the [[thalamus]] and the [[basal ganglia]], sending information to them along [[efferent nerve fiber|efferent connections]] and receiving information from them via [[afferent nerve fiber|afferent connections]]. Most sensory information is routed to the cerebral cortex via the thalamus. Olfactory information, however, passes through the [[olfactory bulb]] to the olfactory cortex ([[piriform cortex]]). The majority of connections are from one area of the cortex to another, rather than from subcortical areas; [[Valentino Braitenberg|Braitenberg]] and Schüz (1998) claim that in primary sensory areas, at the cortical level where the input fibers terminate, up to 20% of the synapses are supplied by extracortical afferents but that in other areas and other layers the percentage is likely to be much lower.<ref>{{cite book | vauthors = Braitenberg V, Schüz A | title = Cortex: Statistics and Geometry of Neuronal Connectivity. | location = New York | publisher = Springer Science & Business Media | date = 1998 | isbn = 978-3-540-63816-2 }}</ref>

===Cortical areas===
{{See also|Cortical map}}
The whole of the cerebral cortex was divided into 52 different areas in an early presentation by [[Korbinian Brodmann]]. These areas, known as [[Brodmann area]]s, are based on their [[cytoarchitecture]] but also relate to various functions. An example is Brodmann area 17, which is the [[Visual cortex#Primary visual cortex (V1)|primary visual cortex]].

In more general terms the cortex is typically described as comprising three parts: sensory, motor, and association areas.

====Sensory areas====
[[File:Blausen 0102 Brain Motor&Sensory.png|thumb|Motor and sensory regions of the cerebral cortex]]

The sensory areas are the cortical areas that receive and process information from the [[senses]]. Parts of the cortex that receive sensory inputs from the [[thalamus]] are called primary sensory areas. The senses of vision, hearing, and touch are served by the primary visual cortex, primary [[auditory cortex]] and [[primary somatosensory cortex]] respectively. In general, the two hemispheres receive information from the opposite (contralateral) side of the [[Human body|body]]. For example, the right primary somatosensory cortex receives information from the left limbs, and the right visual cortex receives information from the left visual [[receptive field|field]].

The organization of sensory maps in the cortex reflects that of the corresponding sensing organ, in what is known as a [[Topographic map (Neuroanatomy)|topographic map]]. Neighboring points in the primary [[visual cortex]], for example, correspond to neighboring points in the [[retina]]. This topographic map is called a [[retinotopy|retinotopic map]]. In the same way, there exists a [[tonotopy|tonotopic map]] in the primary auditory cortex and a [[somatotopy|somatotopic map]] in the primary sensory cortex. This last topographic map of the body onto the [[posterior central gyrus]] has been illustrated as a deformed human representation, the somatosensory [[Cortical homunculus|homunculus]], where the size of different body parts reflects the relative density of their innervation. Areas with much sensory innervation, such as the fingertips and the lips, require more cortical area to process finer sensation.

====Motor areas====
The motor areas are located in both hemispheres of the cortex. The motor areas are very closely related to the control of voluntary movements, especially fine fragmented movements performed by the hand. The right half of the motor area controls the left side of the body, and vice versa.

Two areas of the cortex are commonly referred to as motor:
* [[Primary motor cortex]], which ''executes'' voluntary movements <ref>{{Cite book | vauthors = Moini J, Piran P |chapter=Chapter 6 - Cerebral cortex |chapter-url=https://www.sciencedirect.com/science/article/abs/pii/B9780128174241000069 | veditors = Moini J, Piran P |title= Functional and Clinical Neuroanatomy: A Guide for Health Care Professionals |date=January 2020 |pages=177–240 |publisher=Academic Press |doi=10.1016/B978-0-12-817424-1.00006-9 |isbn=978-0-12-817424-1 }}</ref>
* [[Supplementary motor area]]s and [[premotor cortex]], which ''select'' voluntary movements.<ref>{{Cite book | vauthors = Michelet T, Burbaud P, Gross CE, Bioulac B | chapter = Behavioral Planning: Neurophysiological Approach of the Frontal Lobe Function in Primates |chapter-url= https://www.sciencedirect.com/science/article/abs/pii/B978008045396500213X | veditors = Koob GF, Le Moal M, Thompson RF |title= Encyclopedia of Behavioral Neuroscience|date=January 2010 |pages=145–152 |publisher=Academic Press |doi=10.1016/B978-0-08-045396-5.00213-X |isbn=978-0-08-045396-5 }}</ref>

In addition, motor functions have been described for:
* [[Posterior parietal cortex]], which guides voluntary movements in space
* [[Dorsolateral prefrontal cortex]], which decides which voluntary movements to make according to higher-order instructions, rules, and self-generated thoughts.

Just underneath the cerebral cortex are interconnected subcortical masses of grey matter called [[basal ganglia]] (or nuclei). The basal ganglia receive input from the substantia nigra of the midbrain and motor areas of the cerebral cortex, and send signals back to both of these locations. They are involved in motor control. They are found lateral to the thalamus. The main components of the basal ganglia are the [[caudate nucleus]], the [[putamen]], the [[globus pallidus]], the [[substantia nigra]], the [[nucleus accumbens]], and the [[subthalamic nucleus]]. The putamen and globus pallidus are also collectively known as the [[lentiform nucleus]], because together they form a lens-shaped body. The putamen and caudate nucleus are also collectively called the [[corpus striatum]] after their striped appearance.<ref>Saladin, Kenneth. Anatomy and Physiology: The Unity of Form and Function, 5th Ed. New York: McGraw-Hill Companies Inc., 2010. Print.</ref><ref>Dorland's Medical Dictionary for Health Consumers, 2008.</ref>

====Association areas====
[[File:Cortical areas that have been shown to be involved in speech processing fnhum-06-00099-g005.jpg|thumb|Cortical areas involved in speech processing.]]
The association areas are the parts of the cerebral cortex that do not belong to the primary regions. They function to produce a meaningful [[perception|perceptual experience]] of the world, enable us to interact effectively, and support abstract thinking and language. The [[parietal lobe|parietal]], [[Temporal lobe|temporal]], and [[occipital lobe]]s – all located in the posterior part of the cortex – integrate sensory information and information stored in memory. The [[frontal lobe]] or prefrontal association complex is involved in planning actions and movement, as well as abstract thought. Globally, the association areas are organized as distributed networks.<ref>{{cite journal | vauthors = Yeo BT, Krienen FM, Sepulcre J, Sabuncu MR, Lashkari D, Hollinshead M, Roffman JL, Smoller JW, Zöllei L, Polimeni JR, Fischl B, Liu H, Buckner RL | title = The organization of the human cerebral cortex estimated by intrinsic functional connectivity | journal = Journal of Neurophysiology | volume = 106 | issue = 3 | pages = 1125–1165 | date = September 2011 | pmid = 21653723 | pmc = 3174820 | doi = 10.1152/jn.00338.2011 }}</ref> Each network connects areas distributed across widely spaced regions of the cortex. Distinct networks are positioned adjacent to one another yielding a complex series of interwoven networks. The specific organization of the association networks is debated with evidence for interactions, hierarchical relationships, and competition between networks.

In humans, association networks are particularly important to language function. In the past it was theorized that language abilities are localized in [[Broca's area]] in areas of the left [[inferior frontal gyrus]], [[Brodmann area 44|BA44]] and [[Brodmann area 45|BA45]], for language expression and in [[Wernicke's area]] [[Brodmann area|BA22]], for language reception. However, the processes of language expression and reception have been shown to occur in areas other than just those structures around the [[lateral sulcus]], including the frontal lobe, [[basal ganglia]], [[cerebellum]], and [[pons]].<ref>{{cite journal | vauthors = Price CJ | title = The anatomy of language: contributions from functional neuroimaging | journal = Journal of Anatomy | volume = 197 Pt 3 | issue = Pt 3 | pages = 335–359 | date = October 2000 | pmid = 11117622 | pmc = 1468137 | doi = 10.1046/j.1469-7580.2000.19730335.x }}</ref>