Cortical remapping

Cortical remapping, also referred to as cortical reorganization, is when a cortical map is affected by a stimulus, is changed and then creates a 'new' cortical map.

Cortical remapping in the somatosensory system happens when there has been a decrease in sensory input to the brain due to deafferentation or amputation, as well as a sensory input increase to an area of the brain. Every part of the body is connected to a corresponding area in the brain which creates a cortical map. When something happens to disrupt the cortical maps such as an amputation or a change in neuronal characteristics, the map is no longer relevant. The part of the brain that is in charge of the amputated limb or neuronal change will be dominated by adjacent cortical regions that are still receiving input, thus creating a remapped area.

Dr. Wilder Penfield, a neurosurgeon, was one of the first to map the cortical maps of the human brain. When performing brain surgeries on conscious patients, Penfield would touch either a patient’s sensory or motor brain map, located on the cerebral cortex, with an electric probe to determine if a patient could notice either a specific sensation or movement in a particular area on their body. Penfield also discovered that the sensory or motor maps were topographical; areas of the body adjacent to one another would likely be adjacent on the cortical maps.

Due to Penfield’s work, the scientific community concluded that the brain must be fixed and unchangeable because a specific area of the brain corresponds to a particular point on the body. However, this conclusion was challenged by Michael Merzenich, whom many call “the world’s leading researcher on brain plasticity."

In 1968, Merzenich and two neurosurgeons, Dr. Ron Paul and Herbert Goodman, conducted an experiment to determine effects on the brain after a large bundle of peripheral nerves in adolescent monkeys’ hands were cut and began to regenerate again. They knew that the peripheral nervous system could regenerate itself and sometimes during that process the neurons would ‘rewire’ themselves by accident. These ‘wires’ would accidentally connect to a different axon, stimulating the wrong nerve. This resulted in a “false localization” sensation; when the patient was touched on a specific area of the body, that touch was actually felt on a different part of the body than expected.

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