Researchers at the University of Missouri (MU), Columbia, have found that when an individual has undergone amputation of a dominant hand, he or she is forced to compensate by using the nondominant hand exclusively for precision tasks like writing or drawing. They say their findings may shed light on ways in which a patient compensates when losing a dominant hand and suggest new and improved rehabilitation techniques for those suffering from amputation or stroke. The study was published March 5 in The Journal of Neuroscience.
In the study, individuals with upper-limb amputations forced to use nondominant hands performed simple drawing tests and were checked for speed and accuracy. The researchers found that individuals who were forced to compensate with their nondominant left hands actually performed precision tasks as well as the control group did with their dominant right hands. The same tests were then conducted under functional magnetic resonance imaging (fMRI) so that the subjects’ brain functions could be observed. Researchers found that the areas formerly devoted to motor and sensory functions of the amputated hand actually contributed to compensation for the loss on the nondominant side.
“Most people know that the left side of your brain controls the right hand and vice versa,” said Scott Frey, Miller Family Chair in cognitive neuroscience; a professor in the Department of Psychological Sciences; director of the MU Brain Imaging Center and Rehabilitation Neuroscience Lab; and adjunct professor of the School of Medicine Departments of Neurology, Psychiatry, and Physical Medicine and Rehabilitation. “We found that when amputees were forced to use their nondominant hands for years or decades…their ability to compensate with the left hand appears to involve exploiting brain mechanisms that previously were devoted to controlling their now absent dominant hands. This compensatory reorganization raises the hope that, through targeted training, nondominant hand functions can be vastly improved, enabling a better quality of life for those who have lost dominant hand functions due to bodily or brain injury or disease.”
Although more work is needed, Frey suggested that his team’s work on individuals with amputations may inform rehabilitation of stroke patients who do not regain precision control of the dominant hand during acute and subacute recovery phases. For some patients in the chronic phase of recovery, it may make sense to train the less affected nondominant side.
Editor’s note: This story is adapted from materials provided by the MU News Bureau.