I retired from active research on June 30, 2017. I continue
to have an active ongoing relationship with the Department
of Brain and Cognitive Sciences and the McGovern
Institute for Brain Research at MIT,
and undertake a variety of activities with collaborators.
Through the years,
my research has focused primarily on two questions: 1) how
does the brain handle the enormous complexity involved in
making even the simplest movement. And, 2) how to utilize
muscle synergies for establishing principled ways to restore
limb kinematics compromised by stroke and/or brain injury.
With respect to
the first theme, my collaborators and I provided evidence
for a modular organization of the spinal cord in lower and
higher vertebrates (rats, frogs and monkeys). A "module" is
functional unit in the spinal cord that generates a specific
motor output by expressing a specific pattern of muscle activation
(muscle synergy). Such an organization might help to simplify
the production of movements by reducing the degrees of freedom
that need to be specified.
With respect to the second question, we have garnered experimental
evidence that the muscle synergies with their coefficients of
activation are affected by stroke and head injuries. On the
strength of this observation, I continue to be interested in
ongoing research and consult with various collaborators in quantitatively
evaluating the relationship between affected muscle synergies
and compromised limb kinematics. These studies provide a principled
way to re-establish healthy movements.