Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Switching on one-shot learning in the brain

29.04.2015

Caltech researchers find the brain regions responsible for jumping to conclusions

Most of the time, we learn only gradually, incrementally building connections between actions or events and outcomes. But there are exceptions--every once in a while, something happens and we immediately learn to associate that stimulus with a result. For example, maybe you have had bad service at a store once and sworn that you will never shop there again.


Caltech researchers provide evidence that the amount of uncertainty about the causal relationship between a stimulus and an outcome mediates switching between incremental learning, in which we gradually acquire knowledge, and one-shot learning, where we rapidly learn from a single pairing of a potential stimulus and an outcome. Neuroimaging findings suggest that the ventrolateral prefrontal cortex may act as a "switch," selectively turning one-shot learning on and off, as needed.

Credit: Sang Wan Lee/Caltech

This type of one-shot learning is more than handy when it comes to survival--think, of an animal quickly learning to avoid a type of poisonous berry. In that case, jumping to the conclusion that the fruit was to blame for a bout of illness might help the animal steer clear of the same danger in the future.

On the other hand, quickly drawing connections despite a lack of evidence can also lead to misattributions and superstitions; for example, you might blame a new food you tried for an illness when in fact it was harmless, or you might begin to believe that if you do not eat your usual meal, you will get sick.

Scientists have long suspected that one-shot learning involves a different brain system than gradual learning, but could not explain what triggers this rapid learning or how the brain decides which mode to use at any one time.

Now Caltech scientists have discovered that uncertainty in terms of the causal relationship--whether an outcome is actually caused by a particular stimulus--is the main factor in determining whether or not rapid learning occurs.

They say that the more uncertainty there is about the causal relationship, the more likely it is that one-shot learning will take place. When that uncertainty is high, they suggest, you need to be more focused in order to learn the relationship between stimulus and outcome.

The researchers have also identified a part of the prefrontal cortex--the large brain area located immediately behind the forehead that is associated with complex cognitive activities--that appears to evaluate such causal uncertainty and then activate one-shot learning when needed.

The findings, described in the April 28 issue of the journal PLOS Biology, could lead to new approaches for helping people learn more efficiently. The work also suggests that an inability to properly attribute cause and effect might lie at the heart of some psychiatric disorders that involve delusional thinking, such as schizophrenia.

"Many have assumed that the novelty of a stimulus would be the main factor driving one-shot learning, but our computational model showed that causal uncertainty was more important," says Sang Wan Lee, a postdoctoral scholar in neuroscience at Caltech and lead author of the new paper. "If you are uncertain, or lack evidence, about whether a particular outcome was caused by a preceding event, you are more likely to quickly associate them together."

The researchers used a simple behavioral task paired with brain imaging to determine where in the brain this causal processing takes place. Based on the results, it appears that the ventrolateral prefrontal cortex (VLPFC) is involved in the processing and then couples with the hippocampus to switch on one-shot learning, as needed.

Indeed, a switch is an appropriate metaphor, says Shinsuke Shimojo, Caltech's Gertrude Baltimore Professor of Experimental Psychology. Since the hippocampus is known to be involved in so-called episodic memory, in which the brain quickly links a particular context with an event, the researchers hypothesized that this brain region might play a role in one-shot learning. But they were surprised to find that the coupling between the VLPFC and the hippocampus was either all or nothing. "Like a light switch, one-shot learning is either on, or it's off," says Shimojo.

In the behavioral study, 47 participants completed a simple causal-inference task; 20 of those participants completed the study in the Caltech Brain Imaging Center, where their brains were monitored using functional Magnetic Resonance Imaging. The task consisted of multiple trials. During each trial, participants were shown a series of five images one at a time on a computer screen.

Over the course of the task, some images appeared multiple times, while others appeared only once or twice. After every fifth image, either a positive or negative monetary outcome was displayed. Following a number of trials, participants were asked to rate how strongly they thought each image and outcome were linked. As the task proceeded, participants gradually learned to associate some of the images with particular outcomes. One-shot learning was apparent in cases where participants made an association between an image and an outcome after a single pairing.

The researchers hypothesize that the VLPFC acts as a controller mediating the one-shot learning process. They caution, however, that they have not yet proven that the brain region actually controls the process in that way. To prove that, they will need to conduct additional studies that will involve modifying the VLPFC's activity with brain stimulation and seeing how that directly affects behavior.

Still, the researchers are intrigued by the fact that the VLPFC is very close to another part of the ventrolateral prefrontal cortex that they previously found to be involved in helping the brain to switch between two other forms of learning--habitual and goal-directed learning, which involve routine behavior and more carefully considered actions, respectively. "Now we might cautiously speculate that a significant general function of the ventrolateral prefrontal cortex is to act as a leader, telling other parts of the brain involved in different types of behavioral functions when they should get involved and when they should not get involved in controlling our behavior," says coauthor John O'Doherty, professor of psychology and director of the Caltech Brain Imaging Center.

###

The work, "Neural Computations Mediating One-Shot Learning in the Human Brain," was supported by the National Institutes of Health, the Gordon and Betty Moore Foundation, the Japan Science and Technology Agency-CREST, and the Caltech-Tamagawa global Center of Excellence.

Media Contact

Deborah Williams-Hedges
debwms@caltech.edu
626-395-3227

 @caltech

http://www.caltech.edu 

Deborah Williams-Hedges | EurekAlert!

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

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

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

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>