Comments on: Monkey see, monkey control prosthetic arm with thoughts

By: Andy_T

Andy_T — Wed, 23 Feb 2011 17:13:40 +0000

I’m wondering how long it will take until something makes the experiment ‘more lifelike’ and amputates the monkeys arms, instead of just inserting electrodes into their brains.

What about asking disabled volunteers to participate in this study instead??? That would have the added benefit that they could be explained what the aim of the exercise is, and the results could be transferred to other humans easier…

What, there’s a risk involved? OK, in that case it’s great that the subjects of the study are only non-human animals… something about the article makes me want to puke, scientific progress or not.

By: Coriolis

Coriolis — Fri, 30 May 2008 15:58:56 +0000

Thanks Ed, I looked up the actual paper as well, although I’m still not quite getting it, it’s a bit of a jump from physics.
Do you know what they mean by “unit” and “tuning” in the explanation you quoted? Does it mean “electrode” and “orientation of that electrode”, and by “firing”, whether or not the neuron that is connected to that electrode is firing? And then the monkey learns that if it fires that neuron, the arm will move in the direction that electrode connected to the neuron is associated with?
Or are they somehow directly figuring out which neurons in the cortex are inherently associated with movements in which direction (I find this pretty unlikely).
Basically I’m trying to understand whether they are providing the monkey’s brain with a system to move the arm and then the monkey learns how to use it. Or instead trying to figure out what firing pattern means movement in what direction and then adjusting their program to make the arm move in that way. From what I understand, the first is the correct notion, but I’m not sure.

By: Ed Yong

Ed Yong — Fri, 30 May 2008 11:56:44 +0000

Owlmirror and Paul – thanks for pointing out the earlier research.
Coriolis – Here’s the actual description of the algorithm from the paper (it was a bit difficult to ‘translate’!)

“The population vector algorithm28 (PVA) used here was similar to algorithms used in some cursor-control experiments15, 21. It relies on the directional tuning of each unit, characterized by a single preferred direction in which the unit fires maximally. The real-time population vector is essentially a vector sum of the preferred directions of the units in the recorded population, weighted by the instantaneous firing rates of the units, and was taken here to represent four dimensions

By: Paul

Paul — Fri, 30 May 2008 10:55:38 +0000

Good point Owlmirror, some of the coverage of this story has tended to down play previous research such as that done by Carmena et al in 2003 (though Velliste et al do cite this study in this weeks paper). Andy Schwartz’s group have also published previously on this topic about the manipulation of virtual objects.
Why this study is important is that it demonstrated for the first time the ability to interact with and accuratelly manipulate real objects. Previous BMIs had manipulated virtual objects and moved prostethic limbs but did not manipulate real objects. This study also demonstrates finer control than has been achieved before and shows that fewer neurons needed to be monitored than many researchers had thought.
Perhaps it’s a more incremental step than a revolutionary one, but it’s a pretty important increment!

By: Owlmirror

Owlmirror — Thu, 29 May 2008 22:19:29 +0000

This is the first time that a prosthetic has been placed under direct control of the relevant part of the brain.

Wait a minute - what about the work done at Duke 5 years ago? Learning to Control a Brain–Machine Interface for Reaching and Grasping by Primates Carmena JM, Lebedev MA, Crist RE, O'Doherty JE, Santucci DM, et al. PLoS Biology Vol. 1, No. 2, e42 doi:10.1371/journal.pbio.0000042

Reaching and grasping in primates depend on the coordination of neural activity in large frontoparietal ensembles. Here we demonstrate that primates can learn to reach and grasp virtual objects by controlling a robot arm through a closed-loop brain-machine interface (BMIc) that uses multiple mathematical models to extract several motor parameters (i.e., hand position, velocity, gripping force, and the EMGs of multiple arm muscles) from the electrical activity of frontoparietal neuronal ensembles. As single neurons typically contribute to the encoding of several motor parameters, we observed that high BMIc accuracy required recording from large neuronal ensembles. Continuous BMIc operation by monkeys led to significant improvements in both model predictions and behavioral performance. Using visual feedback, monkeys succeeded in producing robot reach-and-grasp movements even when their arms did not move. Learning to operate the BMIc was paralleled by functional reorganization in multiple cortical areas, suggesting that the dynamic properties of the BMIc were incorporated into motor and sensory cortical representations.

By: Coriolis

Coriolis — Thu, 29 May 2008 21:21:25 +0000

I’m wondering if you could clarify a bit on the program they are using to interpret the brain signals. As far as I understand, every electrode that is put in has a different orientation in space, that is known to the researchers. Basically they can be though of as a set of 116 vectors pointing in different directions in space. And then they are measuring whether the neurons around that electrode are firing. And then they sum over all the vectors corresponding to the electrodes that are firing, and move the arm in that direction? Is that right, or I am completely off?
This means that there is no “pattern-matching” going on, i.e. looking at how the neurons are firing and trying to figure out what the monkey wants, it’s just the monkey is somehow learning that firing these sets of neurons does what it wants to do? Which really is even more impressive to me, if that is the case.

By: Ian

Ian — Thu, 29 May 2008 12:49:30 +0000

“…maybe we could hook up some prosthetic tentacles to people” – PZ would definitely go for that!
I’m wondering if the TV series “Bionic Monkey” is on the fall schedule….

By: Ed Yong

Ed Yong — Wed, 28 May 2008 23:30:02 +0000

I love that my readers look at scientific discoveries and think about how they could be used for evil. Max, for example, appears to be intent on turning himself into Doctor Octopus... Oh and Warren, you're thinking of penguins.

By: Warren

Warren — Wed, 28 May 2008 22:58:18 +0000

So … how long before they learn how to fling poo at ballistic velocities?

By: mike spear

mike spear — Wed, 28 May 2008 22:43:34 +0000

woops looked at it again, looks like the arm wasn’t actually attached.