The wonder of human movement

by Angela Herring

To watch a bal­le­rina move is to observe, per­haps, the pin­nacle of coor­di­na­tion, to expe­ri­ence pre­cise and exquisite ele­gance. But now imagine a rhythmic gym­nast, who must not only move with the artic­u­lated grace of a dancer but must simul­ta­ne­ously manip­u­late a ball, hoop, or ribbon with extreme control.

“She extends her move­ments toward the object. She is one with the object,” said Dagmar Sternad, pro­fessor of biologyelec­trical and com­puter engi­neering, and physics at Northeastern.

On Tuesday after­noon, Sternad received the 50th annual Robert D. Klein Uni­ver­sity Lec­turer Award and deliv­ered her uni­ver­sity lec­ture, titled “The wonder of human move­ment: How the brain con­trols the body.” She dis­played images of gym­nasts and dancers to high­light their incred­ible level of phys­ical control.

On the flip side, she said, are indi­vid­uals who suffer from dis­or­ders and ail­ments such as Parkinson’s dis­ease, cere­bral palsy, or stroke. Damage to the neural system of the brain robs these patients of con­trol over their limbs and move­ments. “We have no cure,” Sternad said. “We have ways to ame­lio­rate the symp­toms, but no cure.”

The Robert D. Klein Uni­ver­sity Lec­turer Award, estab­lished in 1964 upon the rec­om­men­da­tion of the Fac­ulty Senate, honors a member of the fac­ulty who has con­tributed with dis­tinc­tion to his or her own field of study. In 1979, it was renamed in tribute to the late Klein, a revered pro­fessor of math­e­matics and a leader in the Faculty Senate.

Stephen W. Director, provost and senior vice pres­i­dent for aca­d­emic affairs, pre­sented the award to Sternard. Director char­ac­ter­ized her as “a bril­liant edu­cator, a remark­able speaker, a leader, and an impas­sioned researcher.”

Sternad, who directs the Action Lab at North­eastern, is an inter­na­tion­ally known authority in the field of exper­i­mental and com­pu­ta­tional motor neu­ro­science. Her diverse aca­d­emic career has spanned the dis­ci­plines of move­ment sci­ence, Eng­lish lin­guis­tics and lit­er­a­ture, exper­i­mental psy­chology, neu­ro­science, and kine­si­ology. Her studies of human motor con­trol and learning have shed light on neu­ro­log­ical defects in Parkinson patients, chil­dren with dys­tonia, and indi­vid­uals who have suf­fered strokes.

In her lec­ture, Sternad elab­o­rated on the com­plexity of the human brain, which con­sists of between 10 bil­lion and 100 bil­lion neu­rons, each making thou­sands of con­nec­tions with all the others. “This is an unfath­omable net­work with 100 tril­lion con­nec­tions,” she explained. How does this infi­nitely com­plex struc­ture turn infor­ma­tion into phys­ical move­ments? And how can we use that process to help patients who cannot con­trol their movements?

In a first step to answering these ques­tions, devel­oping appro­priate inter­ven­tions for patients, and under­standing how bal­lerinas and gym­nasts achieve such remark­able con­trol over their move­ments, Sternad’s team works back­wards. Instead of starting with the neu­rons that cause the move­ment, they start with the behavior.

“We start by picking a task that is inter­esting,” Sternad said. This may be car­rying a cup of coffee or bouncing a ball. They then work to under­stand the physics of the task in order to render it in a vir­tual envi­ron­ment, where they can exper­i­men­tally probe a human’s per­for­mance. Based on what they learn, they can design inter­ven­tions to help people modify their movements.

“It is unlikely that humans con­trol their move­ments by learning the pre­cise mus­cles that are con­trol­ling a given task,” Sternad explained. Instead, we gather extrinsic infor­ma­tion about it, such as per­for­mance feed­back in a game. “We then find solu­tions in the task that make our vari­ability less detrimental.”

Her research has shown that though we may not under­stand the math­e­mat­ical cal­cu­la­tions that go into a task, we learn and respond to its physics the more we prac­tice it. For instance, in the game table skit­tles, in which a player must skill­fully launch a teth­ered ball in order to knock down a small pin, there are areas on the ball’s ellip­tical tra­jec­tory where releasing it will be more likely to result in suc­cess. Though we may not know this, as we per­form the game over and over we begin to release the ball just inside that sweet spot, she said.

Her work has shown that people with Parkinson’s dis­ease have con­trol over their tra­jec­tory but not over the timing of their release of the ball. “We can [use] that insight to focus our inter­ven­tions,” she explained.

Still, even the most highly trained and skilled ath­letes can crack under pres­sure. In order to sim­u­late the sense of com­pe­ti­tion threat that may be present during, say, the Olympics or the World Series, Sternad has part­nered with North­eastern Uni­ver­sity psy­chology pro­fessor Stephen Harkins to develop exper­i­ments in which par­tic­i­pants must play the game either with or without addi­tional infor­ma­tion about their like­li­hood of suc­cess. “We tell them there are gender dif­fer­ences,” she said. Indeed, invoking threat causes that nuanced com­mu­ni­ca­tion between brain and body to degrade. “So mind mat­ters,” Sternad said.

Originally published in news@Northeastern on April 9, 2014.

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Posted in Biology, Physics

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