Behavioral and Electrophysiological Evidence of Motor Cortex Activation Related to an Amputated Limb: A Multisensorial Approach

The article I chose was called “Behavioral and Electrophysiological Evidence of Motor

Cortex Activation Related to an Amputated Limb: A Multisensorial Approach.” The researchers of this article were Pascale Touzalin-Chretien, Solange Ehrler, and André Dufour. I chose this article because I am very interested in the phenomenon of phantom limb in amputees. Working in a rehabilitation facility I hear many of the amputees describe having achy pains or having an itchy feeling in their amputated limb. It is fascinating to both the patient and I because you would think that there would be no pain or itchiness in the amputated limb, but it still remains. For those who do not known what phantom limb sensations are it is the “impression that an amputated limb is still present.”

There were two purposes of this research. The first was “whether cortical motor areas can activate by visual inputs form the corresponding limb.” The second was “whether cortical activations corresponding to the missing limb can affect motor performances of the remaining limb.” The aims were measured by having the participant behind a mirror which gave the illusion that their missing limb was still intact when performing a motor task. There were a total of eight participants: four with traumatic upper-limb loss and four with congenital upper-limb loss that were broken down into two experiments.

The first experiment focused on proprioceptive persistence for those who were missing a limb due to trauma. The researchers measured the motor performance of the remaining hand by asking the participants to draw an object on a mirror task using a digital pen. Researchers found that the mirror-drawing can improve missing or inactive movements in both traumatic and congenital amputees which was seen from the motor cortex. The second experiment used the information found in the first experiment and added a third group of normal participants. These participants had to complete a task with either their right hand or their intact hand by pressing a button quickly when a light appeared. There were three positions used: direct view, sagital mirror view, and a frontal view.

            There were many results found in this study. One, interesting finding was that, those who were in the normal limbed group and the trauma amputees group dealt with visuopropriceptive information in a very similar manner. Both groups had more difficulties performing the task when the mirror was placed in the frontal view. Secondly, this research found that proprioceptive sensations could emerge from the missing limb when the remaining limb was viewed through a mirror, even when the amputation occurred many years later. Thirdly, it was interesting to read that those who lost a limb through trauma and those who not born with a limb both experienced phantom sensations. Lastly, this article showed the hemisphere that was contralateral to the amputation indicated neural activity in the primary motor cortex with respect to the amputated hand.

Source:

Touzalin-Chretien, P., Ehrler, S., & Dufour, A. (2009). Behavioral and Electrophysiological Evidence of Motor Cortex Activation Related to an Amputated Limb: A Multisensorial Approach. Journal of Cognitive Neuroscience, 21(11), 2207-2216. Retrieved from EBSCOhost.