Targeted motor and sensory reinnervation (TMSR) is a surgical procedure on patients with amputations that reroutes residual limb nerves towards intact muscles and skin in order to fit them with a limb prosthesis allowing unprecedented control.
By its nature, TMSR changes the way the brain processes motor control and somatosensory input; however, the detailed brain mechanisms have never been investigated before and the success of TMSR prostheses will depend on our ability to understand the ways the brain re-maps these pathways. In a research conducted last year, EPFL scientists used ultra-high field 7 Tesla fMRI to show how TMSR affects upper-limb representations in the brains of patients with amputations, in particular in primary motor cortex and the somatosensory cortex and regions processing more complex brain functions. The findings were published in Brain.
Surprisingly, the study showed that motor cortex maps of the amputated limb were similar in terms of extent, strength, and topography to individuals without limb amputation, but they were different from patients with amputations that did not receive TMSR, but were using standard prostheses. This shows the unique impact of the surgical TMSR procedure on the brain’s motor map.
The approach was even able to identify maps of missing (phantom) fingers in the somatosensory cortex of the TMSR patients that were activated through the reinnervated skin regions from the chest or residual limb. (1)
We are part of the cosmos, feeling and sensing everything.
But senses can be lost. Senses can be regained.
The brain can learn to move arms which are not anymore.
But only because they were once there.
We can learn again to move mountains.
Only because we once used to…
See that mountain. It seems big.
Start with that small rock.
Try to move it.
Then the other one.