Question

Which of the following explains why V. S. Ramachandran was able to elicit a sensation in a patient's amputated limb by gently touching the patient's face?

a.) Sensory neurons dedicated to the upper arm and face remapped to the brain region once used by the lower arm

b.) The neurons required for sensation in the lower arm died.

c.) The face and lower arm use the same sensory neurons.

d.) The amputation of the limb caused a trauma in the brain as well.

Answer 1

The sensation in a patient's amputated limb is not due to something inside the amputed stump but it due to there is remapping of cortical areas of the brain once which received fibers from it. It created cortical plasticity and beacuse of this area without nerve area can taken over by sorrounding regions which provide the healthy signal and active input. There are sensory nerves in the brain. Face is located near to upper arm and leg near to genital. When sensory neurones dedicated to the upper arm and face ramapped to the brain region once used by the lower arm.

Hence option (a) is correct.