For more than a hundred years, physicians have published accounts of people who perceive an amputated arm or leg as if it were still there. Many amputees feel burning, cramping, or shooting pains in these phantom limbs.
Doctors explained this by saying that the patients went through a denial period due to the trauma of loosing a body-part. Experts have discovered
in the last decade that the sensations which the amputees have been reporting,
is due to a manifestation called Phantom limb phenomena.
The neurobiologists have been chasing the phantom. Their first attempts were to figure out were do the sensations originate. When a limb is amputated, the severed nerves that formerly carried messages of touch , temperature, and pain from the skin, form nodules on their cut ends, called neuromas. For years, the favored explanation was, that the cut nerve endings continue to send impulses up the spinal cord to the brain.
This explanation was repealed when the neurosurgeons cut just above the neuromas. The proof was in the fact that the relief was temporary and therefore that the sensation must be emanating from the brain. The discovery, that the sense of touch emanates from our heads rather than our fingertips, leads the researchers onto a new dimension in neuroscience.
It is known to us that when the receptors of the neurons are stimulated, an electrical impulse is generated. It travels through the spinal cord, to the brain stem. This electrical impulse travels further to the relay station - thalamus, and from there to the somatosensory cortex. This area has been accurately mapped out. Each area of skin has its lot in the cortex. The more receptors active in an area of skin, the bigger will be its allotment. With this in mind, scientists outlined the diagram of...