Neuroplasticity in Action

Key Takeaways

• Phantom limb syndrome is explained by cortical remapping, where the brain reassigns sensory inputs to adjacent areas post-amputation.

• Edward Taub's Constraint-Induced Movement Therapy (CIMT) promotes neuroplasticity, aiding recovery in stroke patients by constraining healthy limbs.

• Functional MRI studies confirm increased brain activity in areas associated with improved function, supporting the effectiveness of CIMT.

• Neuroplasticity enables the adult nervous system to reorganize post-lesion, enhancing rehabilitation outcomes and shifting paradigms in neurorehabilitation.

After reading about cortical remapping of the monkey’s brain, neurologist V.S. Ramachandran, MD, PhD, surmised that a similar phenomenon may explain the baffling syndrome of phantom limb, which had befuddled medical researchers and clinicians alike since it was first described by Silas Weir Mitchell, MD, shortly after the Civil War.

Ramachandran examined a 17-year-old adolescent who had his left arm amputated 3 weeks prior in a motor vehicle accident and reported that it felt as if this arm was still present. Having the patient keep his eyes tightly closed, Ramachandran brushed the patient’s left cheek with a cotton swab in various locations. Upon asking the patient where he felt the sensations, the patient noted it was on his left cheek, but also on his amputated hand, thumb, and index finger. Remarkably, the patient reported that when he felt an itch on his phantom palm, he felt relief by scratching his lower face.

Ramachandran hypothesized that this patient’s brain had cortically remapped the postamputation silent somatosensory cortex on the postcentral gyrus associated with the left hand to the adjacent incoming neurons from the facial nerve. It is well established that the area of the postcentral gyrus that maps to the left hand borders the area that maps the left face. This was a concrete example of neuroplasticity in action.

In the 1980s, Edward Taub, PhD, the chief scientist at the Institute for Behavioral Research in Silver Spring, Maryland, developed a hypothesis based on his research with monkeys: If the innervation of 1 arm was seriously damaged but the healthy arm was constrained so it could not be used to accomplish necessary tasks, the possibility existed for the patient to regain function in the damaged arm with structured physical therapy. During the 1990s this hypothesis was proven by research in post cerebral vascular accident (CVA) using a technique called Constraint-Induced Movement Therapy (CIMT).

In a review article that detailed the clinical applications in humans that had thus far been established, the authors wrote, “Research from several laboratories has shown that the adult nervous system can reorganize after a lesion,” concretizing the paradigm shift toward human neuroplasticity. Also in 2002, researchers leveraged functional magnetic resonance imaging to confirm an increase in brain activity in the cortical area involved in the increased function.

Using functional magnetic resonance imaging technology, patients who engage in this [CIMT] therapy have been shown to have increased activity in their contralateral premotor and secondary somatosensory cortex in association with improved function.

A 2011 review on the management of CVAs summarized the research demonstrating the role of neuroplasticity in rehabilitation from strokes, and the effectiveness of CIMT.

Note: This article originally appeared on Psychiatric Times.