Cut­ting edge pros­thet­ics

Man moves pros­thetic fin­gers with his mind.

The Star Malaysia - Star2 - - HEALTH - By AN­DREA K. MCDANIELS

AF­TER Darth Vader lopped off Luke Sky­walker’s hand in the movie The Em­pire Strikes Back, Rebel Al­liance doc­tors in­stalled a pros­thetic that im­me­di­ately moved and felt just like a hu­man hand.

Sci­ence fic­tion is com­ing closer to re­al­ity at Johns Hop­kins in the US, where re­searchers re­cently adapted a brain map­ping tech­nol­ogy to en­able a pa­tient to in­de­pen­dently move in­di­vid­ual fin­gers on a pros­thetic arm just by think­ing about it.

While such tech­nol­ogy is years from prac­ti­cal ap­pli­ca­tion in pa­tients, the break­through by biomed­i­cal en­gi­neers and physicians from the Johns Hop­kins Univer­sity and its School of Medicine is the lat­est ad­vance­ment in a grow­ing field of re­search into mind- con­trolled move­ment of ar­ti­fi­cial limbs.

The Johns Hop­kins re­searchers said their work, pub­lished this month in the Jour­nal of Neu­ral En­gi­neer­ing, is the first to ac­com­plish such pre­cise, in­di­vid­u­alised mo­tion of the fin­gers and shows prom­ise for one day pro­vid­ing am­putees with pros­thet­ics that more closely mimic the move­ments of real hands and arms.

While pros­thet­ics have im­proved in re­cent years, they still can be bulky and hard to ma­noeu­vre. The fin­gers on ex­ist­ing pros­thet­ics move as one unit, or in uni­son, open­ing and clos­ing to­gether, like when grasp­ing a soda can.

“We still have a bit of a ways to go be­fore we get this in a prac­ti­cal clin­i­cal set­ting fully restor­ing the nat­u­ral dex­ter­ity of peo­ple – but I think that day is com­ing,” said Guy Hot­son, an elec­tri­cal and com­puter en­gi­neer­ing grad­u­ate stu­dent at Johns Hop­kins, who was lead au­thor on the study.

There are more than 100,000 peo­ple in the United States with am­pu­tated hands or arms who could po­ten­tially ben­e­fit from such pros­thet­ics, ac­cord­ing to the Am­putee Coali­tion, an education, sup­port and ad­voca- cy or­gan­i­sa­tion.

“The mind con­trol re­search is very cut­ting edge,” said Ge­orge Gondo, the coali­tion’s di­rec­tor of re­search and grants. “It is re­ally ex­cit­ing to see im­prove­ment and to see ac­tual re­sults from the re­search.”

Funded by the US Na­tional In­sti­tute of Neu­ro­log­i­cal Dis­or­ders and Stroke, the ex­per­i­ment used a mod­u­lar pros­thetic arm de­vel­oped by Johns Hop­kins Ap­plied Physics Lab­o­ra­tory.

Con­sid­ered the world’s most so­phis­ti­cated up­per- ex­trem­ity pros­the­sis, the arm can per­form al­most all of the same move­ments as a hu­man arm and hand.

The lab’s re­search and de­vel­op­ment of the arm it­self was funded un­der the Rev­o­lu­tion­iz­ing Pros­thet­ics pro­gramme of De­fense Ad­vanced Re­search Projects Agency with the in­tent of restor­ing limb func­tion to wounded mil­i­tary mem­bers.

While build­ing such a me­chan­i­cally so­phis­ti­cated pros­the­sis is pos­si­ble, how to con­trol it re­mains an open ques­tion.

That’s where the Johns Hop­kins re­searchers thought that brain- map­ping tech­nol­ogy known as elec­tro­cor­ticog­ra­phy could be used. But they needed a sub­ject to whom they could ap­ply sen­si­tive elec­trodes di­rectly to the brain.

Be­cause the study in­volved open­ing the brain, the re­searchers needed to find some­one al­ready get­ting surgery for some­thing else, so they re­cruited a young epilep­tic man un­der­go­ing brain surgery to stop seizures not con­trolled by medicine.

As part of the pro­ce­dure, doc­tors placed elec­trodes on the pa­tient’s brain to help de­ter­mine where his seizure orig­i­nated, and then re­moved those parts of his brain.

The sur­geons ap­plied the same brain map­ping tech­nique to de­ter­mine which parts of his brain con­trolled fin­ger move­ment.

A set of 128 elec­trodes sit­ting on a film the size of a credit card were placed on the parts of the brain that con­trol hand and arm move­ment. Each sen­sor mea­sured a mil­lime- ter of brain tis­sue.

The re­searchers then asked the pa­tient, who was awake through­out the surgery, to move in­di­vid­ual fin­gers. The com­puter pro­gramme de­vel­oped by Johns Hop­kins en­gi­neers recorded the parts of the brain that were ac­ti­vated through elec­tri­cal sig­nals de­tected by the sen­sors as he moved each fin­ger.

Re­searchers also tracked which parts of the brain re­sponded to sen­sory in­put from the fin­gers by hav­ing the pa­tient wear a glove with vi­brat­ing buzzers on each fin­ger and mea­sur­ing the sub­se­quent elec­tri­cal ac­tiv­ity.

Us­ing the data col­lected from the pa­tient’s brain, the pros­thetic arm was pro­grammed to move par­tic­u­lar fin­gers when cor­re­spond­ing parts of the brain were ac­ti­vated.

The pros­thetic arm was then wired to the elec­trodes in the pa­tient’s brain and turned on. When he was asked to think about mov­ing par­tic­u­lar fin­gers, his brain ac­tiv­ity moved the fin­gers on the pros­the­sis.

The pa­tient was not an am­putee and could con­trol both of his arms. The metal and plas­tic pros­thetic was mounted so that he could see it as it moved.

The pa­tient also did not have to do un­dergo any train­ing to make the fin­gers move as pa­tients in other stud­ies have had to do.

The pros­thetic arm still needs years of de­vel­op­ment, the re­searchers said. For one, it needs to con­nect to a com­puter run­ning the soft­ware to work.

“Most of what is be­ing done here is not built into the arm,” said Dr Nathan Crone, pro­fes­sor of neu­rol­ogy at the Johns Hop­kins Univer­sity School of Medicine who was part of the study.

“Some day, when this is used by pa­tients, it will prob­a­bly re­quire some faster com­put­ing and even­tu­ally it could fit in the arm. Right now it would re­quire some kind of com­put­ing pack some­body would carry around. You need the com­puter near the arm in or­der for it work.”

The Am­putee Coali­tion’s Gondo said mo­tion- con­trolled tech­nol­ogy has the po­ten­tial to im­prove the lives of am­putees – from the types of jobs they do, to their abil­ity to live in­de­pen­dently.

Even if the tech­nol­ogy is per­fected for mind- con­trolled pros­thet­ics, cost re­mains a huge ob­sta­cle for wide­spread ap­pli­ca­tion. A mod­u­lar pros­thetic can cost half a mil­lion dol­lars, said Hot­son.

“It will be in­ter­est­ing to see how and if they are able to bring any of this tech­nol­ogy to mar­ket; that’s al­ways a chal­lenge,” Gondo said. “Par­tic­u­larly with up­per limb pros­thet­ics be­cause it is such a small per­cent­age of the pop­u­la­tion.”

It could be years be­fore mind- con­trolled pros­thet­ics are even ready for com­mer­cial­i­sa­tion, the Hop­kins re­searchers said.

“We are not go­ing to see this in pa­tients right away,” Crone said. “Th­ese are just the first steps to­ward that tech­nol­ogy.” – The Bal­ti­more Sun/ Tribune News Ser­vice

Re­searchers at Johns Hop­kins are at­tempt­ing to cre­ate a pros­thetic arm that can be moved by brain waves. — TNS

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