Editing Phantom limb (section)

===Neural mechanisms===
Pain, temperature, touch, and pressure information are carried to the [[central nervous system]] via the anterolateral system ([[spinothalamic tract]]s, [[spinoreticular tract]], spinomesencefalic tract), with pain and temperature information transferred via lateral spinothalamic tracts to the [[primary sensory cortex]], located in the [[postcentral gyrus]] in the [[parietal lobe]], where sensory information is represented somatotropically, forming the [[sensory homunculus]].<ref>{{Cite journal|last1=Kaur|first1=Amreet|last2=Guan|first2=Yuxi|date=December 2018|title=Phantom limb pain: A literature review|journal=Chinese Journal of Traumatology|volume=21|issue=6|pages=366–368|doi=10.1016/j.cjtee.2018.04.006|pmid=30583983|issn=1008-1275|doi-access=free|pmc=6354174}}</ref> Somatotopic representation seems to be a factor in the experience of phantom limb, with larger regions in the sensory homunculus typically experiencing more phantom sensations or pain. These areas include the hands, feet, fingers and toes.

In phantom limb syndrome, there is sensory input indicating pain from a part of the body that is no longer existent. This phenomenon is still not fully understood, but it is hypothesized that it is caused by activation of the [[somatosensory cortex]].<ref name=":1">{{Citation |last1=Nikolajsen |first1=Lone |title=Phantom Limb Pain |date=2015 |url=http://dx.doi.org/10.1016/b978-0-12-802653-3.00051-8 |work=Nerves and Nerve Injuries |pages=23–34 |access-date=2023-11-05 |publisher=Elsevier |last2=Christensen |first2=Kristian Friesgaard|doi=10.1016/b978-0-12-802653-3.00051-8 |isbn=9780128026533 |url-access=subscription }}</ref> One theory is it may be related to central sensitization, which is a common experience among amputees. Central sensitization is when there are changes in the responsiveness of the neurons in the dorsal horn of the spinal cord, which deals with processing somatosensory information, due to increased activity from the peripheral nociceptors. Peripheral nociceptors are sensory neurons that alert us to potentially damaging stimuli.<ref name=":1" />

There are theories that the phantom limb phenomenon may relate to reorganization of the somatosensory cortex after the limb is removed. When the body receives tactile input near the residual limb, the brain is convinced that the sensory input was received from the amputated limb because another brain region took over. Reorganization has been thought to be related to sensory-discriminative parts of pain as well as the affective-emotional parts of it (I.e., insula, the anterior cingulate cortex, and the frontal cortices).<ref>{{Cite journal |last1=Willoch |first1=Frode |last2=Rosen |first2=Gunnar |last3=Tolle |first3=Thomas Rudolf |last4=Oye |first4=Ivar |last5=Wester |first5=Hans Jurgen |last6=Berner |first6=Niels |last7=Schwaiger |first7=Markus |last8=Bartenstein |first8=Peter |date=December 2000 |title=Phantom limb pain in the human brain: Unraveling neural circuitries of phantom limb sensations using positron emission tomography |url=https://onlinelibrary.wiley.com/doi/10.1002/1531-8249(200012)48:6%3C842::AID-ANA4%3E3.0.CO;2-T |journal=Annals of Neurology |language=en |volume=48 |issue=6 |pages=842–849 |doi=10.1002/1531-8249(200012)48:6<842::AID-ANA4>3.0.CO;2-T |issn=0364-5134 |pmid=11117540 |s2cid=2206540|url-access=subscription }}</ref>

Phantom sensations can also occur when there has been a peripheral nerve injury resulting in deafferentation. This causes changes in the dorsal horn of the spinal cord, which normally has an inhibitory effect on sensory transmission.<ref name=":0" />