Editing Motor cortex (section)

==History==
In 1870, [[Eduard Hitzig]] and [[Gustav Fritsch]] demonstrated that electrical stimulation of certain parts of the dog brain resulted in muscular contraction on the opposite side of the body.<ref name=Fritsch&Hitzig>{{cite journal | author=[[Gustav Fritsch|Fritsch, G]] and [[Eduard Hitzig|Hitzig, E]] | title=Über die elektrische Erregbarkeit des Grosshirns | journal=Archiv für Anatomie, Physiologie und Wissenschaftliche Medicin | year=1870 | pages=300–332}} Translated in: {{cite book | editor=von Bonin, G. | title=Some Papers on the Cerebral Cortex | year=1960 | publisher=Charles Thomas |location= Springfield IL | pages=73–96}}</ref> This confirmed experimentally the existence of a cortical motor center, which was inferred by Jackson a few years earlier on the basis of clinical observations.<ref>{{Cite book |last=Jackson |first=JH |title=Selected writings of John Hughlings Jackson |publisher=Hodder and Stoughton |year=1931}}</ref> Together with Broca's (1861)<ref>{{Cite journal |last=Broca |first=P |date=1861 |title=Sur le principe des localisations cérébrales |journal=Bulletin de la Société d'Anthropologie |volume=2 |pages=190–204}}</ref> discovery of a language center in the left hemisphere of the cerebral cortex, the demonstration of a cortical motor center put an end to Flourens' <ref>{{Cite book |last=Flourens |first=MJP |title=Recherches expérimentales sur les propriétés et les fonctions du systeme nerveux dans les animaux vertébrés |date=1842 |publisher=Crevot |location=Paris}}</ref> doctrine (1842) that function was widely distributed across the cerebral cortex (i.e., not localized).<ref>{{Cite journal |last=Capaday |first=Charles |date=2004 |title=The Integrated Nature of Motor Cortical Function |url=http://journals.sagepub.com/doi/10.1177/107385403262109 |journal=The Neuroscientist |language=en |volume=10 |issue=3 |pages=207–220 |doi=10.1177/107385403262109 |issn=1073-8584 |pmid=15155060 |s2cid=7174916}}</ref>

A little later, in 1874, [[David Ferrier]],<ref name=Ferrier>{{cite journal | author=[[David Ferrier|Ferrier, D]] | year=1874 | title=Experiments on the brain of monkeys - No. 1 | journal=Proc. R. Soc. Lond. | volume= 23 | pages=409–430 | doi=10.1098/rspl.1874.0058 | issue=156–163| s2cid=144533070 }}</ref> working in the laboratory of the [[Stanley Royd Hospital|West Riding Lunatic Asylum]] at [[Wakefield]] (at the invitation of its director, [[James Crichton-Browne]]), mapped the motor cortex in the monkey brain using electrical stimulation.  He found that the motor cortex contained a rough map of the body with the feet at the top (or dorsal part) of the brain and the face at the bottom (or ventral part) of the brain. He also found that when electrical stimulation was maintained for a longer time, such as for a second, instead of being discharged over a fraction of a second, then some coordinated, seemingly meaningful movements could be caused, instead of only muscle twitches.

After Ferrier's discovery, many neuroscientists used electrical stimulation to study the map of the motor cortex in many animals including monkeys, apes, and humans.<ref name=Campbell>{{cite book | author=Campbell, A. W. | year=1905 | title=Histological Studies on the Localization of Cerebral Function | location=Cambridge, MA | publisher=Cambridge University Press | oclc=6687137 | url=https://archive.org/details/histologicalstu00campgoog | url-status=live | archive-url=https://web.archive.org/web/20160602130611/https://archive.org/details/histologicalstu00campgoog | archive-date=2016-06-02 }}</ref><ref name=Vogt&Vogt>{{cite journal | author1-link=Cécile Vogt-Mugnier|last1=Vogt|first1=C.|last2=Vogt|first2=O.|author2-link=Oskar Vogt| year=1919 | title=Ergebnisse unserer Hirnforschung | journal=Journal für Psychologie und Neurologie | volume=25 | pages=277–462}}</ref><ref name=Foerster>{{cite journal | author=[[Otfrid Foerster|Foerster, O]] | year=1936 | title=The motor cortex of man in the light of Hughlings Jackson's doctrines | journal=Brain | volume=59 | pages=135–159 | doi=10.1093/brain/59.2.135 | issue=2}}</ref><ref name=Beevor&Horsley>{{cite journal | author=[[Charles Edward Beevor|Beevor, C.]] and [[Victor Horsley|Horsley, V]] | year=1887 | title=A minute analysis (experimental) of the various movements produced by stimulating in the monkey different regions of the cortical centre for the upper limb, as defined by Professor Ferrier | journal=Phil. Trans. R. Soc. Lond. B | volume=178 | pages=153–167 | doi=10.1098/rstb.1887.0006| doi-access=free }}</ref><ref name=Grunbaum&Sherrington>{{cite journal | author=Grunbaum A. and [[Charles Sherrington|Sherrington, C]] | year=1901 | title=Observations on the physiology of the cerebral cortex of some of the higher apes. (Preliminary communication) | journal=Proc. R. Soc. Lond. | volume=69 | pages=206–209 | doi=10.1098/rspl.1901.0100 | issue=451–458| bibcode=1901RSPS...69..206G | doi-access= | s2cid=145245312 }}</ref>

One of the first detailed maps of the human motor cortex was described in 1905 by Campbell.<ref name=Campbell/> He did autopsies on the brains of amputees. A person who had lost an arm would over time apparently lose some of the neuronal mass in the part of the motor cortex that normally controls the arm. Likewise, a person who had lost a leg would show degeneration in the leg part of motor cortex. In this way the motor map could be established. In the period between 1919 and 1936 others mapped the motor cortex in detail using electrical stimulation, including the husband and wife team [[Cécile Vogt-Mugnier|Vogt]] and [[Oskar Vogt|Vogt]],<ref name=Vogt&Vogt/> and the neurosurgeon [[Otfrid Foerster|Foerster]].<ref name=Foerster/>

Perhaps the best-known experiments on the human motor map were published by Penfield in 1937.<ref name=Penfield&Boldrey>{{cite journal | author1-link=Wilder Penfield|last1=Penfield|first1=W.|last2=Boldrey|first2=E. | year=1937 | title=Somatic motor and sensory representation in the cerebral cortex of man as studied by electrical stimulation | journal=Brain | volume=60 | pages=389–443 | doi=10.1093/brain/60.4.389 | issue=4}}</ref><ref name=Penfield>{{cite journal | author=[[Wilder Penfield|Penfield, W.]] | year=1959 | title=The interpretive cortex | journal=Science | volume=129 | pages=1719–1725 | pmid=13668523 | issue=3365|doi=10.1126/science.129.3365.1719 | bibcode=1959Sci...129.1719P | s2cid=37140763 }}</ref> Using a procedure that was common in the 1930s, he examined epileptic patients who were undergoing brain surgery. These patients were given a local anesthetic, their skulls were opened, and their brains exposed. Then, electrical stimulation was applied to the surface of the brain to map out the speech areas.  In this way, the surgeon would be able to avoid any damage to speech circuitry. The brain focus of the epilepsy could then be surgically removed. During this procedure, Penfield mapped the effect of electrical stimulation in all parts of the cerebral cortex, including motor cortex.

Penfield is sometimes mistakenly considered to be the motor cortex map discoverer. It was discovered approximately 70 years before his work. However, Penfield drew a picture of a human-like figure stretched over the cortical surface and used the term "homunculus" (diminutive of "homo", Latin for "man") to refer to it. It is perhaps for this reason that his work has become so popular in neuroscience. Penfield knew the homunculus idea was a caricature. He stated, '<nowiki/>''It is a cartoon of representation in which scientific accuracy is impossible''<nowiki/>'.<ref>{{Cite book |last=Penfield W and Rasmussen T |title=The cerebral cortex of man: a clinical study of localization of function |publisher=McMillan |year=1950 |location=New York}}</ref> Nearly fifty years before,<ref>{{Cite book |last=Sherrington |first=C.S. |title=The integrative action of the nervous system |publisher=Yale University Press |year=1947 |edition=2nd |location=New Haven}}</ref> Sherrington (1906) made the point more cogently stating '''The student looking over the political map map of a continent may little realise the complexity of the populations and states so simply represented. We looking at the brain chart of the text book may never forget the unspeakable complexity of the reactions thus rudely symbolised and spatially indicated''´. While pictures of an orderly representation of limb segments across the cortical surface (such as the one shown above) have endured in textbooks, they are erroneous and misleading.<ref>{{Cite journal |last1=Capaday |first1=Charles |last2=Ethier |first2=Christian |last3=Van Vreeswijk |first3=Carl |last4=Darling |first4=Warren G. |date=2013 |title=On the functional organization and operational principles of the motor cortex |journal=Frontiers in Neural Circuits |volume=7 |page=66 |doi=10.3389/fncir.2013.00066 |doi-access=free |issn=1662-5110 |pmc=3629310 |pmid=23616749}}</ref>