Lasers, mag­netism per­mit ex­perts to see brain at work


To the un­trained eye, the graph looked like a very volatile day on Wall Street — jagged peaks and val­leys in red, blue and green, dis­played on a wall. But the story it told was not about eco­nom­ics.

It was a glimpse into the brains of Shaul Yahil and Shaw Bron­ner, two re­searchers at a Yale Univer­sity lab, as they had a lit­tle chat.

“This is a fork,” Yahil ob­served, de­scrib­ing the im­age on his com­puter. “A fork is some­thing you use to stab food while you’re eat­ing it. Com­mon piece of cut­lery in the West.”

“It doesn’t look like a real fancy ster­ling sil­ver fork, but very use­ful,” Bron­ner re­sponded. And then she de­scribed her own screen: “This looks like a baby chim­panzee...”

The jagged, mul­ti­col­ored im­ages de­picted what was go­ing on in the two re­searchers’ heads — two brains in con­ver­sa­tion, car­ry­ing out an in­tri­cate dance of in­ter­nal ac­tiv­ity. This is no par­lor trick. The brain-track­ing tech­nol­ogy at work is just a small part of the quest to an­swer abid­ing ques­tions about the work­ings of a 1.4-kilo­gram chunk of fatty tis­sue with the con­sis­tency of cold por­ridge.

How does this col­lec­tion of nearly 100 bil­lion densely packed nerve cells, act­ing through cir­cuits with maybe 100 tril­lion con­nec­tions, let us think, feel, act and per­ceive our world? How does this com­plex ma­chine go wrong and make peo­ple de­pressed, or delu­sional, or de­mented? What can be done about that?

Such ques­tions spurred U. S. Pres­i­dent Barack Obama to launch the BRAIN ini­tia­tive in 2013. Its aim: to spur de­vel­op­ment of new tools to in­ves­ti­gate the brain. Europe and Ja­pan are also pur­su­ing ma­jor ef­forts in brain re­search.

The mys­ter­ies of this or­gan, which sucks up about 20 per­cent of the body’s energy, are many and pro­found. But with a col­lec­tion of so­phis­ti­cated de­vices, sci­en­tists are peer­ing in­side the work­ing brains of peo­ple for clues to what makes us tick.

At the Yale lab, Yahil and Bron­ner were de­mon­strat­ing a tech­nique be­ing used there to in­ves­ti­gate how our brains let us en­gage with other peo­ple.

That’s one of

the most

ba­sic ques­tions in neu­ro­science, as well as an abil­ity im­paired in autism and schizophre­nia, said lab di­rec­tor Joy Hirsch.

As the two re­searchers chat­ted, each wore a black-and-white skullcap from which 64 slen­der black ca­bles trailed away like dreadlocks. At the tip of half of those fiber op­tic ca­bles, weak laser beams slipped through their skulls and pen­e­trated about 2.5 cen­time­ters into their brains. There, the beams bounced off blood and re­flected back to be picked up by the other half of the ca­bles.

Those re­flec­tions re­vealed how much oxy­gen that blood was car­ry­ing. And since brain cir­cuits use more oxy­gen when they’re busier, the mea­sure­ments pro­vided an in­di­rect in­dex to pat­terns of brain ac­tiv­ity as Bron­ner lis­tened to Yahil and replied, and vice versa.

The most widely used brain­map­ping tech­nique, how­ever, is a dif­fer­ent one called func­tional mag­netic res­o­nance imag­ing, or fMRI. Ba­si­cally, fMRI does what Hirsch’s laser sys­tem does: It uses oxy­gen lev­els in blood as trac­ers of brain-cell ac­tiv­ity. But it pen­e­trates much deeper into the brain, us­ing pow­er­ful mag­netic fields. That lets it seek sub­tle mag­netic sig­nals to track blood oxy­gen lev­els on a tiny scale; a bump in oxy­gen lev­els in­di­cates ac­tive brain cells nearby.

The fMRI tech­nol­ogy can de­tect van­ish­ingly tiny changes in brain ac­tiv­ity that are as­so­ci­ated with tack­ling par­tic­u­lar tasks. And it can show the ac­tiv­ity of a brain that is not fo­cused on do­ing a task. In this rest­ing state, the brain con­tin­ues to hum along, and sci­en­tists are study­ing what this can re­veal about it and its ill­nesses.

Another ma­jor em­pha­sis in brain map­ping these days is de­lin­eat­ing the cir­cuitry that lets the brain op­er­ate.

Com­mu­ni­ca­tion flows along an es­ti­mated 240,000 kilo­me­ters of nerve fibers in the av­er­age brain. In­di­vid­ual fibers are too fine to see in brain-scan­ning ma­chines, but they form bun­dles that can be de­tected as they cross the deep cen­tral por­tion of the brain.

Those bun­dles are one fo­cus of re­searchers who are map­ping out the brain’s “con­nec­tome,” the com­plex web of these con­nec­tions be­tween ar­eas of gray mat­ter, where think­ing takes place. One goal is bet­ter un­der­stand­ing what parcels of tis­sue do what jobs in the brain’s outer layer, the cere­bral cor­tex.

Some brain-scan­ning re­search rises from the in­for­ma­tive to the truly star­tling, like de­cod­ing — look­ing at brain ac­tiv­ity pat­terns to fig­ure out what some­body is see­ing, or even think­ing about.

In 2011, for ex­am­ple, re­searchers re­ported that they could re­con­struct very rough vis­ual repli­cas of movie clips that peo­ple were watch­ing while their brains were scanned. And two years later, Ja­panese sci­en­tists re­ported ev­i­dence that they could get some idea of what peo­ple were dream­ing about — at least, bet­ter than chance un­der highly con­trolled con­di­tions.

Such find­ings are valu­able for learn­ing how the brain is or­ga­nized. And in the near term, de­cod­ing tech­nol­ogy might help peo­ple whose med­i­cal con­di­tion pre­vents nor­mal con­ver­sa­tion, said Jack Gallant of the Univer­sity of Cal­i­for­nia, Berke­ley.

If por­ta­ble de­vices that peer closely into the brain can be de­vel­oped, new pos­si­bil­i­ties open up for brain de­cod­ing. And not just for sci­en­tists.

Gallant fore­sees a fu­ture in which com­posers write mu­sic just by imag­in­ing it. Or “you can just think about the pic­ture you want to paint” and let a com­puter do the rest.

Writ­ing a let­ter, he says “would be like dic­ta­tion, ex­cept you would just be talk­ing to your­self.”

And in the fu­ture, why be con­fined to your own lan­guage?

“I can think in English and my lit­tle brain hat would read my thoughts, send it to Google and it would come back in Ja­panese,” he says. “You’d talk out of a lit­tle speaker in your hat.”


Shaw Bron­ner, left, and Shaul Yahil, two re­searchers at the Yale Brain Func­tion Lab, de­scribe im­ages on their com­puter screens to each other while their brain ac­tiv­ity is mapped dur­ing a demon­stra­tion of the tech­nol­ogy in New Haven, Con­necti­cut on Fri­day, March 13.

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