Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Deciding to stay or go is a deep-seated brain function

07.06.2011
Birds do it. Bees do it. Even little kids picking strawberries do it.

Every creature that forages for food decides at some point that the food source they're working on is no richer than the rest of the patch and that it's time to move on and find something better.

This kind of foraging decision is a fundamental problem that goes far back in evolutionary history and is dealt with by creatures that don't even have proper brains, said Michael Platt, a professor of neurobiology and director of the Center for Cognitive Neuroscience at Duke University.

Platt and his colleagues now say they've identified a function in the primate brain that appears to be handling this stay-or-go problem. They have found that the dorsal anterior cingulate cortex (ACC), an area of the brain known to operate while weighing conflicts, steadily increases its activity during foraging decisions until a threshold level of activity is reached, whereupon the individual decides it's time to move on.

In lab experiments with rhesus macaque monkeys, Platt and postdoctoral fellows Benjamin Hayden and John Pearson put the animals through a series of trials in which they repeatedly had to decide whether to stay with a source that was giving ever-smaller squirts of fruit juice, or move to another, possibly better, source. The animals were merely gazing at a preferred target on a display screen, not moving from one tree to the next, but the decision-making process should be the same, Platt said.

For the other variable in this basic equation, travel time, the researchers added delays when monkeys chose to leave one resource and move to another, simulating short and long travel times.

As the monkeys repeatedly chose to stay with their current source or move to another, the researchers watched a small set of neurons within the anterior cingulate cortex fire with increasing activity for each decision. The rate of firing in this group of neurons grew until a threshold was reached, at which time the monkey immediately decided to move on, Platt said. "It is as if there is a threshold for deciding it's time to leave set in the brain," he said.

When the researchers raised the "travel time" to the next foraging spot in the experiment, it raised the decision-making threshold, Platt said.

This all fits with a 1976 theory by evolutionary ecologist Eric Charnov, called the Marginal Value Theorem, Platt said. It says that all foragers make calculations of reward and cost that tell them to leave a patch when their intake diminishes to the average intake rate for the overall environment. That is, one doesn't pick a blueberry bush until it's bare, only until it looks about as abundant as the bushes on either side of it. Shorter travel time to the next patch means it costs less to move, and foragers should move more easily. This theorem has been found to hold in organisms as diverse as worms, bees, wasps, spiders, fish, birds, seals and even plants, Platt said.

"This is a really fundamental solution to a fundamental problem," Platt said.

Platt said the work also relates to recent papers on the Web-browsing habits of humans. In the case of Internet users, the cost of travel time translates to download speed. The faster the downloads, the quicker browsers are willing to forage elsewhere, Platt said.

They aren't sure yet where the brain's signaling goes after the stay-or-go threshold in the ACC is reached. Platt believes this kind of "integrate-to-threshold" mechanism would be a good way to handle a lot of functions in the brain and may be found in other kinds of systems. This particular threshold in the ACC might also be a way to explain maladaptive behaviors like attention deficit, in which a person decides to move on constantly, or compulsive behavior, in which a person can't seem to move on at all, he said.

The research appears online in Nature Neuroscience, June 5, 2011. It was supported by the National Institutes of Health and a fellowship from the Tourette Syndrome Association.

CITATIONS:

"Neuronal basis of sequential foraging decisions in a patchy environment," Benjamin Y. Hayden, John M. Pearson, Michael L. Platt. Nature Neuroscience, Advance Online, June 5, 2011. doi: 10.1038/nn.2856

"Information foraging," Pirolli, Peter; Card, Stuart Psychological Review, Vol 106(4), Oct 1999, 643-675. doi: 10.1037/0033-295X.106.4.643

Karl Leif Bates | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>