<P> By the late 1980s, Ronald Melzack had recognized that the peripheral neuroma account could not be correct . In his 1989 paper, "Phantom Limbs, The Self And The Brain" Melzack proposed the hypothesis of the "neuromatrix ." According to Melzack the experience of the body is created by a wide network of interconnecting neural structures . In 1991, Tim Pons and colleagues at the National Institutes of Health (NIH) showed that the primary somatosensory cortex in macaque monkeys undergoes substantial reorganization after the loss of sensory input . </P> <P> Vilayanur S. Ramachandran hypothesized that phantom limb sensations in humans could be due to reorganization in the somatosensory cortex, which is located in the postcentral gyrus, and which receives input from the limbs and body . Ramachandran and colleagues illustrated this hypothesis by showing that stroking different parts of the face led to perceptions of being touched on different parts of the missing limb . Ramachandran argued that the perception of being touched in different parts of the phantom limb was the perceptual correlate of cortical reorganization in the brain . However, research published in 1995 by Flor et al. demonstrated that pain (rather than referred sensations) was the perceptual correlate of cortical reorganization . In 1996 Knecht et al. published an analysis of Ramachandran's hypothesis that concluded that there was no topographic relationship between referred sensations and cortical reorganization in the primary cortical areas . Recent research by Flor et al. suggests that non-painful referred sensations are correlated with a wide neural network outside the primary cortical areas . </P> <P> Not all scientists support the hypothesis that phantom limb pain is the result of maladaptive changes in the cortex . Pain researchers such as Tamar Makin (Oxford) and Marshall Devor (Hebrew University, Jerusalem) argue that phantom limb pain is primarily the result of "junk" inputs from the peripheral nervous system . </P> <P> Despite a great deal of research on the underlying neural mechanisms of phantom limb pain there is still no clear consensus as to its cause . Peripheral mechanisms (areas of the nervous system outside the brain) and central neural mechanisms (inside the cortex) are among the hypotheses that have gained the most support over recent years . However, none of these theoretical constructs appears to be able to explain the phenomenon of phantom limb pain independently and many experts believe that multiple mechanisms are likely responsible . </P>

What part of the brain does phantom limb effect