BRAIN-POW­ERED SPI­DER BOTS

Why are mini-brains be­ing used to con­trol ro­bots?

Focus-Science and Technology - - HUMANS - JV Chamary is a sci­ence writer and editor, with a back­ground in evo­lu­tion­ary bi­ol­ogy and ge­net­ics.

Neu­ro­sci­en­tist Alysson Muotri is putting organoids in­side four-legged, spi­der-like ro­bots. The main rea­son for such an un­usual mind-ma­chine in­ter­face is that it en­ables the ‘brains’ to ex­plore the world around them – via an ar­ti­fi­cial body. “They’re sim­i­lar to a new­born baby who’s try­ing to get used to touch­ing things and ex­pe­ri­enc­ing dif­fer­ent sen­sa­tions,” Muotri ex­plains.

Elec­tri­cal ac­tiv­ity rises as an em­bry­onic brain de­vel­ops but reaches a plateau be­fore birth, need­ing ex­ter­nal in­put from the senses for its neu­ral cir­cuits to ma­ture. In a spi­der bot, elec­trodes cap­ture ac­tiv­ity from the organoid’s cells and split the elec­tri­cal out­put be­tween the ro­bot’s limbs, which must then syn­chro­nise. “In a very sim­plis­tic way, that’s ex­actly what the hu­man brain does when a baby is try­ing to crawl or walk,” says Muotri. “So we’re teach­ing the organoid how to make this spi­der ro­bot walk, by co­or­di­nat­ing move­ments of the legs.”

It’s al­ready learn­ing. The ‘brain’ can cur­rently tell its body to move for­ward; the next step is teach­ing it to go back­ward when it en­coun­ters an ob­sta­cle, which re­quires pro­vid­ing feed­back for when a move­ment is wrong. That brain train­ing is be­ing achieved in two ways. The first method is a form of ‘mind con­trol’ called op­to­ge­net­ics, in which cells are ge­net­i­cally en­gi­neered to to be sen­si­tive to light so that their be­hav­iour can be con­trolled. The sec­ond method in­volves sup­ply­ing cells with a dose of the re­ward hor­mone, dopamine. Both meth­ods cause the organoid’s neu­ral net­works to re­ar­range, al­low­ing it to adapt.

Once organoids are able to learn, they can bat­tle in ro­bot wars – ob­vi­ously not a fight, but a com­pe­ti­tion of speed. An organoid made from Ne­an­derthalised cells with a NOVA1 gene vari­ant has de­fects in synap­tic con­nec­tions be­tween its cells, af­fect­ing its neu­ral net­works. Would that make it slower to adapt com­pared to a hu­man organoid? While spec­u­la­tive, the re­sults could of­fer clues on whether our hu­man an­ces­tors were faster at think­ing, in­flu­enc­ing their be­hav­iour.

The spi­der bot, with its mul­ti­ple legs, is al­low­ing Muotri’s lab to ob­serve how a sin­gle organoid han­dles co­or­di­na­tion. One fol­low-up ex­per­i­ment would be to see how sev­eral organoids deal with co­op­er­a­tion. Would they in­ter­act to ac­com­plish a com­mon goal? The de­sign for co­op­er­at­ing ro­bots is still in the plan­ning stages – it might in­volve two or three hu­man-like arms that must work to­gether to lift an ob­ject, or ro­botic ver­sions of so­cial in­sects like ants and bees. “This might sound like sci­ence fic­tion,” says Muotri, “but it is ac­tu­ally hap­pen­ing, and they have a clear pur­pose.”

2 food to fuel an en­ergy-hun­gry body in a cold cli­mate. With mod­ern hu­mans, on the other hand, the trade-off meant that we had more pro­cess­ing power for so­cial skills, con­tribut­ing to our evo­lu­tion­ary suc­cess.

An­cient vari­ants con­tinue to af­fect hu­mans to­day, as re­vealed by cer­tain men­tal ill­ness and neu­ro­log­i­cal dis­or­ders. For ex­am­ple, ‘neu­rotyp­i­cal’ peo­ple have one copy of a set of 25 genes lo­cated on chro­mo­some 7, whereas a per­son with the con­di­tion ‘Dup 7’ has a du­pli­ca­tion that cre­ates two copies of each gene. This pro­vides bet­ter vis­ual and spa­tial skills but makes them less so­cia­ble – as in autism. At the other end of the spec­trum, ‘Wil­liams syn­drome’ re­sults from a dele­tion of those same 25 genes, lead­ing to poor vis­ual and spa­tial skills but hy­per-so­cia­bil­ity, which pro­duces some­one with a ‘gre­gar­i­ous brain’ who has a com­pul­sion to strike up con­ver­sa­tions with strangers.

So study­ing the im­pact of ge­netic mu­ta­tions by com­par­ing organoids, in­clud­ing those with an­cient vari­ants found in Ne­an­derthals, can pro­vide in­sights into con­di­tions that af­fect mod­ern hu­mans. “This could pro­vide in­for­ma­tion not only about what makes us who and what we are, but also pos­si­bly pave the way for treat­ment and di­ag­nos­tic ap­proaches,” ex­plains Ber­man.

That’s ac­tu­ally the main rea­son why Muotri is grow­ing mini-brains. His lab con­tains thou­sands of mu­tant organoids for var­i­ous dis­eases. He’s al­ready found that, like Ne­an­derthalised struc­tures, ‘autis­tic’ organoids have de­fects in their neu­ral net­works. “One mis­con­cep­tion many peo­ple have is that by study­ing the evo­lu­tion of the brain, there is no ben­e­fit to hu­man health,” says Muotri, whose son suf­fers from autism. “By un­der­stand­ing how the so­cial brain evolved, we might be able to cre­ate bet­ter ther­a­peu­tics.”

“By un­der­stand­ing how the so­cial brain evolved, we might be able to cre­ate bet­ter ther­a­peu­tics”

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