Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Read Monkeys’ Inner Thoughts

23.07.2012
Anyone who has looked at the jagged recording of the electrical activity of a single neuron in the brain must have wondered how any useful information could be extracted from such a frazzled signal.

But over the past 30 years, researchers have discovered that clear information can be obtained by decoding the activity of large populations of neurons.

Now, scientists at Washington University in St. Louis, who were decoding brain activity while monkeys reached around an obstacle to touch a target, have come up with two remarkable results.

Their first result was one they had designed their experiment to achieve: they demonstrated that multiple parameters can be embedded in the firing rate of a single neuron and that certain types of parameters are encoded only if they are needed to solve the task at hand.

Their second result, however, was a complete surprise. They discovered that the population vectors could reveal different planning strategies, allowing the scientists, in effect, to read the monkeys’ minds.

By chance, the two monkeys chosen for the study had completely different cognitive styles. One, the scientists said, was a hyperactive type, who kept jumping the gun, and the other was a smooth operator, who waited for the entire setup to be revealed before planning his next move. The difference is clearly visible in their decoded brain activity.

The study was published in the July 19th advance online edition of the journal Science.

All in the task

The standard task for studying voluntary motor control is the “center-out task,” in which a monkey or other subject must move its hand from a central location to targets placed on a circle surrounding the starting position.

To plan the movement, says Daniel Moran, PhD, associate professor of biomedical engineering in the School of Engineering & Applied Science and of neurobiology in the School of Medicine at Washington University in St. Louis, the monkey needs three pieces of information: current hand and target position and the velocity vector that the hand will follow.

In other words, the monkey needs to know where his hand is, what direction it is headed and where he eventually wants ot to go.

A variation of the center-out task with multiple starting positions allows the neural coding for position to be separated from the neural coding for velocity.

By themselves, however, the straight-path, unimpeded reaches in this task don’t let the neural coding for velocity to be distinguished from the neural coding for target position, because these two parameters are always correlated. The initial velocity of the hand and the target are always in the same direction.

To solve this problem and isolate target position from movement direction, doctoral student Thomas Pearce designed a novel obstacle-avoidance task to be done in addition to the center-out task.

Crucially, in one-third of the obstacle-avoidance trials, either no obstacle appeared or the obstacle didn’t block the monkey’s path. In either case, the monkey could move directly to the target once he got the “go” cue.

The population vector corresponding to target position showed up during the third hold of the novel task, but only if there was an obstacle. If an obstacle appeared and the monkey had to move its hand in a curved trajectory to reach the target, the population vector lengthened and pointed at the target. If no obstacle appeared and the monkey could move directly to the target, the population vector was insignificant.

In other words, the monkeys were encoding the position of the target only when it did not lie along a direct path from the starting position and they had to keep its position “in mind” as they initially moved in the “wrong” direction.

“It’s all,” Moran says, “in the design of the task.”

And then some magic happens

Pearce’s initial approach to analyzing the data from the experiment was the standard one of combining the data from the two monkeys to get a cleaner picture.

“It wasn’t working,” Pearce says, “and I was frustrated because I couldn’t figure out why the data looked so inconsistent. So I separated the data by monkey, and then I could see, wow, they’re very different. They’re approaching this task differently and that’s kind of cool.”

The difference between the monkey’s’ styles showed up during the second hold. At this point in the task, the target was visible, but the obstacle had not yet appeared.

The hyperactive monkey, called monkey H, couldn’t wait. His population vector during that hold showed that he was poised for a direct reach to the target. When the obstacle was then revealed, the population vector shortened and rotated to the direction he would need to move to avoid the obstacle.

The smooth operator, monkey G, in the meantime, idled through the second hold, waiting patiently for the obstacle to appear. Only when it was revealed did he begin to plan the direction he would move to avoid the obstacle.

Because he didn’t have to correct course, monkey G’s strategy was faster, so what advantage was it to monkey H to jump the gun? In the minority of trials where no obstacle appeared, monkey H approached the target more accurately than monkey G. Maybe monkey H is just cognitively adapted to a Whac-A-Mole world. And monkey G, when caught without a plan, was at a disadvantage.

Working with the monkeys, the scientists had been aware that they had very different personalities, but they had no idea this difference would show up in their neural recordings.

“That’s what makes this really interesting,” Moran says.

Diana Lutz | Newswise Science News
Further information:
http://www.wustl.edu

More articles from Life Sciences:

nachricht 127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere

nachricht How gut bacteria can make us ill
18.01.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

How gut bacteria can make us ill

18.01.2017 | Life Sciences

On track to heal leukaemia

18.01.2017 | Health and Medicine

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>