Remote­ly Quan­ti­fy­ing Visuo­mo­tor Learn­ing with and with­out Movement

Olivia:
Okay.

Speak­er 2:
I see it.

Olivia:
Cool, thanks. So my name is Olivia and I’m a post-doc at Prince­ton work­ing in Jor­dan Tay­lor’s lab. But today I’m going to show you some data that I col­lect­ed in col­lab­o­ra­tion with Alex For­rence and Sam McDougle at Yale, where we remote­ly quan­ti­fied visu­al motor learn­ing and test­ed whether or not a move­ment was­n’t real­ly a require­ment for this kind of adap­ta­tion. But first, I’m going to take a sec­ond to dis­cuss how stud­ies of motor learn­ing have often been tight­ly con­trolled, which JT and Ryan both touched on that. So here again is an armed robot. And in the lab, we main­tain pre­cise con­trol over both how peo­ple are mov­ing. So we can keep that move­ment in a sin­gle plane and apply forces to it. But we can also con­trol exact­ly what they’re see­ing. We can con­ceal the vision of the hand and present feed­back via a mon­i­tor and a mir­ror pre­sent­ing data at a spe­cif­ic frame rate.

Olivia:
Addi­tion­al­ly, dur­ing these exper­i­ments, the exper­i­menter is usu­al­ly present. So we pro­vide instruc­tions to the par­tic­i­pant. And if there are any kinds of con­fu­sions, or if we notice that the per­son is doing some­thing wrong, we can clar­i­fy and cor­rect to make sure that the task is going on, as we antic­i­pate. And one big ques­tion that we had going into research this year, espe­cial­ly con­sid­er­ing COVID, is whether or not we can observe canon­i­cal motor adap­ta­tion online, where we have less control?

Olivia:
So we don’t have con­trol over how par­tic­i­pants are doing the task. Like Ryan said, they might be using a track pad or a mouse, and we did­n’t want to place some require­ment to use either, in case peo­ple lied, when they report­ed the objects that they were using. And addi­tion­al­ly, peo­ple might be sit­ting up, they might be lying down, they could be in any con­fig­u­ra­tion, which could affect the bio­me­chan­ics of their move­ment. Addi­tion­al­ly, peo­ple are at home so they might be dis­tract­ed by sur­pris­ing nois­es or some kind of inter­rup­tion from a pet or a fam­i­ly mem­ber or alter­nate­ly, just the temp­ta­tion to look at your phone since it’s always there. And there’s nobody to ask you not to.

Olivia:
So in addi­tion to that high­er lev­el method­olog­i­cal ques­tion we had, the research ques­tion about whether move­ment was actu­al­ly nec­es­sary for implic­it motor adap­ta­tion. So in stan­dard tri­als and reach­ing tasks, which is what I’m going to use today, usu­al­ly the tar­get is pre­sent­ed and there’s some cue to start that move­ment and peo­ple move their hand towards the tar­get and receive some visu­al feed­back in term, in the form of a visu­al­ly dis­played cur­sor. To induce learn­ing, we present this rota­tion and instruct­ing peo­ple to aim direct­ly at the tar­get and then ignore the move­ment of the cur­sor, restricts this error to a sen­so­ry pre­dic­tion error. So the devi­a­tion between your hand posi­tion and the cur­sor posi­tion is a very salient sig­nal for brain regions like the cere­bel­lum, that actu­al­ly caus­es learn­ing. So in this fig­ure here from one of Ryan’s papers in 2017, on the Y axis, we have hand angle or change in hand angle, which is the mea­sure­ment move­ment in this task.

Olivia:
And when peo­ple are instruct­ed to ignore the move­ment of the cur­sor and all they get is this sen­so­ry pre­dic­tion error, you can see here that there is a grad­u­al­ly change to coun­ter­bal­ance that rota­tion. And peo­ple are unaware of this hap­pen­ing, so we call it implic­it adap­ta­tion. On tri­als with­out move­ment, what we did, is we pre­sent­ed this cue for par­tic­i­pants to reach towards the tar­get, but then change it to magen­ta, to indi­cate to them, to with­hold their reach. And then we played a sim­u­lat­ed per­son move­ment show­ing a visu­al error of miss­ing the tar­get. So on both kinds of tri­als, visu­al errors are dis­played regard­less of whether par­tic­i­pants actu­al­ly moved. And we asked whether implic­it adap­ta­tion occurs under both con­di­tions. Is all that’s need­ed, some kind of rep­re­sen­ta­tion of the goal plus some error, or do we actu­al­ly need to move in order to learn to update that move­ment in the future. We employed a sin­gle tri­al learn­ing design in order to min­i­mize the effects of distractions.

Olivia:
So in a tra­di­tion­al block design, sort of like what I showed you in Ryan’s paper, we mea­sure cumu­la­tive effects over hun­dreds of tri­als. So there’s some base­line peri­od and then hun­dreds of tri­als of manip­u­la­tion. And when there a break in the study, as shown in this paper from Hyosub Kim, there is some effect on task per­for­mance and it’s unpre­dictable how breaks by self-guid­ed par­tic­i­pants at any giv­en time could intro­duce noise in this cumu­la­tive learn­ing sig­nal. So we employed a sin­gle tri­al learn­ing design to mea­sure effects across a triplet of tri­als. In this par­tic­u­lar design, we mea­sured move­ments on tri­al 1, intro­duced some per­tur­ba­tion that rota­tion or visu­al error on the last slide and mea­sured move­ment again on tri­al 3. The dif­fer­ence between move­ments on these 2 tri­als was called The Learn, the amount of learn­ing from the per­tur­ba­tion or the learn­ing from that tri­al, and this lim­its the effects of dis­trac­tions to the triplets on which they occur.

Olivia:
And it allows us to eas­i­ly exclude these tri­als with per­haps poor reac­tion times or long inter tri­al inter­vals with min­i­mal data loss. Addi­tion­al­ly, the tra­di­tion­al block design is hours long and maybe some­what repet­i­tive. And with­out an exper­i­menter there to sug­gest that peo­ple should stay engaged in the task, doing exact­ly the same thing of hun­dreds of times in the row, it might be quite bor­ing and pro­mote dis­trac­tion. Where­as on the sin­gle tri­al learn­ing design, we have a vari­ety of things hap­pen­ing on dif­fer­ent tri­als. So per­haps with this vari­abil­i­ty, we encour­age peo­ple to stay more inter­est­ed in what’s going on and per­haps look away less often. Also in this par­tic­u­lar study, we pre­sent­ed a vari­ety of kinds of triplets, but broad­ly we had triplets with move­ment on this mid­dle probe tri­al and tri­als with­out move­ment that rota­tion applied could either have been zero degrees or plus or minus 15 degrees.

Olivia:
So we can mea­sure adap­ta­tion in response to both direc­tions of error and hope­ful­ly base­line adap­ta­tion with no change in move­ment with a zero degree of rota­tion. And these flick­ing tri­als con­tained no feed­back so we can get a pure mea­sure­ment of the change of move­ment. And again, that change in move­ment was mea­sured across tri­als 1 and 3.

Olivia:
We took some addi­tion­al efforts to stream­line the remote par­tic­i­pant expe­ri­ence, pre­sum­ing that hap­py par­tic­i­pants that under­stand what’s going on will pro­mote a good data col­lec­tion, where­as peo­ple who are con­fused or frus­trat­ed will take our mon­ey and will pro­mote data that we can’t real­ly use lat­er. So Alex For­rence took some efforts using Phas­er, which is an online HTML5 free game frame­work to make these, our instruc­tions, very leg­i­ble and visu­al­ly appeal­ing. So as you can see the text scrolls across the screen, draw­ing your visu­al atten­tion and hope­ful­ly encour­ag­ing peo­ple to read it. Addi­tion­al­ly, if peo­ple made an error that we could detect pro­gram­mat­i­cal­ly, we give them a right reminder. So that’s a task where some­body moved when they were sup­posed to with­hold their move­ment and they see this mes­sage again, to ensure that the instruc­tions are actu­al­ly received in case they clicked through quick­ly, the first time they were shown.

Olivia:
And in order to ver­i­fy that instruc­tions were under­stood, so we had some con­trols built into the exper­i­men­tal design. So, for instance, we can mea­sure peo­ple that were mov­ing the mouse when they were instruct­ed not to and exclude those tri­als or par­tic­i­pants. But we also pre­sent­ed a brief mul­ti­ple choice quiz after this study.

Olivia:
There were three ques­tions with three answers each. So, if they were pure­ly guess­ing, only about 4% of respons­es should be cor­rect. And we found that pro­vid­ing some incen­tive to attend to the quiz actu­al­ly seemed to improve our abil­i­ty to gauge whether peo­ple under­stood what was going on. So with­out an incen­tive about 48% of pro­lif­ic par­tic­i­pants answered all ques­tions cor­rect­ly, which was a lit­tle bit dis­ap­point­ing and kind of con­fus­ing since the data from peo­ple who answered the atten­tion checks cor­rect were very sim­i­lar to the data from peo­ple who did not, but pro­vid­ing a $0.50 bonus to get all of the ques­tions cor­rect, increased that num­ber to about 74% of pro­lif­ic par­tic­i­pants and revealed on big­ger dif­fer­ences and peo­ple who appeared to under­stand the instruc­tions and peo­ple who did not. So this is a lit­tle bit more expen­sive, but it pro­vides some peace of mind about the data qual­i­ty and at least whether or not we’re effec­tive­ly com­mu­ni­cat­ing the instruc­tions to people.

Olivia:
And one last thing that we did was stream­line the remote par­tic­i­pant expe­ri­ence to make things a lit­tle bit eas­i­er in the lab because we have con­trol over the absolute start­ing loca­tion. And the cur­sor is tied to the hand posi­tion, with the start­ing of the patients shown in this white cir­cle here. We can con­cealed the hand in between tri­als and only show the dis­tance between the hand and the cen­ter of the loca­tion by the diam­e­ter or the radius of a green cir­cle that appears on the screen. And when peo­ple move clos­er to the cen­ter, that cir­cle gets small­er, but it does­n’t reveal the X and Y coor­di­nates with their hand. This is a much eas­i­er in per­son because you have some kind of pro­pri­o­cep­tive infor­ma­tion, but a lot of peo­ple strug­gled with this online. So what Alex did is he set up a sys­tem where when the cur­sor moved past the tar­get, it would auto­mat­i­cal­ly reap­pear close to the cen­ter here. So you can see that hap­pen again.

Olivia:
And this reduce the occur­rence of unusu­al­ly long search times that were over 12 sec­onds or some­times over 30 sec­onds. And it reduced the aver­age inter tri­al inter­val, allow­ing us to fit more tri­als into the same amount of time while reduc­ing par­tic­i­pant com­plaints about the dif­fi­cul­ty of the task and not real­ly affect­ing the degree of learn­ing that we saw. So if I just show you the data that we col­lect­ed from this study, you can see that visu­al errors were suf­fi­cient to dri­ve motor adap­ta­tion, or in oth­er words, move­ment was not nec­es­sary. So on the tri­als with move­ment on the pro­pi­ti­a­tion tri­al, you can see that when no rota­tion was applied, there was no adap­ta­tion, but when a 15 degree rota­tion was applied, there was about three degrees of adap­ta­tion across the triplet. Sim­i­lar­ly, when tri­als with­out move­ment were pre­sent­ed, we saw about two degrees of adap­ta­tion in the pres­ence of a 15 degree rotation.

Olivia:
And I don’t know if I showed that this was a sig­nif­i­cant main effect of rota­tion, indi­cat­ing that adap­ta­tion occurs under both con­di­tions in this study. Sim­i­lar­ly, the amount of sin­gle tri­al learn­ing that we observed here is con­sis­tent with pre­vi­ous and lab stud­ies. So this is a fig­ure com­piled by Hyosub Kim, show­ing the learn­ing rate in a vari­ety of stud­ies over the years of doing reach­ing tasks. And if we super­im­pose our data, you can see that both tri­als with move­ment and tri­als with­out move­ment fall with­in the range of what’s been observed before, which is encour­ag­ing and sug­gests that we’re tap­ping into the same process that was tapped into by these stud­ies in the lab.

Olivia:
So as an ini­tial sum­ma­ry, we’ve shown that the motor adap­ta­tion on a patient can be mea­sured online, sim­i­lar to what JT talked about in the intro­duc­tion. And this occurs despite our lack of con­trol over the absolute hand posi­tion, the type of mouse that par­tic­i­pants are using, and the envi­ron­ment that they’re doing the task in, sug­gest­ing that implic­it adap­ta­tion, at least at the lev­el of sin­gle tri­als, maybe a high­er lev­el fea­ture of motor con­trol. It’s not depen­dent on the spe­cif­ic fea­tures of move­ments across sub­jects. Which is encour­ag­ing and sug­gest that like pre­vi­ous find­ings in the lab should be gen­er­al­iz­able out­side of the lab and in time more situations.

Olivia:
And regard­ing our research ques­tions, we’ve demon­strat­ed that move­ment is not real­ly required for implic­it motor adap­ta­tion as it’s sim­i­lar when par­tic­i­pants move, or remain still when they view an error, and move­ments them­selves don’t need to be tied to errors to be the basis for motor adap­ta­tion. And I’d like to take a sec­ond to thank you for your time and to thank my coau­thors for every­thing that they’ve con­tributed my col­leagues, and our fund­ing sources. That’s more data. If you want to talk about that.

Speak­er 2:
Great, Olivia, thank you very much.