Michael Frank, an assistant professor of psychology and director of the Laboratory for Neural Computation and Cognition at The University of Arizona, headed a team whose results are reported in the Oct. 1 issue of Early Edition, an online site hosted by the Proceedings of the National Academy of Sciences.
Frank and his colleagues found links to learning behaviors in three separate genes associated with dopamine. Dopamine is a neurotransmitter, a chemical in the brain that is often associated with pleasure, learning and other behaviors. Several neurological disorders, such as Parkinson's disease, are also linked to abnormal levels of dopamine.
Frank's study points to fundamental genetic differences between "positive" and "negative" learners.
"All three genes affect brain dopamine functioning, but in different ways, and in different parts of the brain" Frank said. "The genes predicted people's ability to learn from both the positive and negative outcomes of their decisions."
Two of the genes - DARPP-32 and DRD2 - predicted learning about the average, long-term probability of rewards and punishments, not unlike your personal preference for why, for example, you might choose steak over salmon.
"When making these kinds of choices, you do not explicitly recall each individual positive and negative outcome of all of your previous such choices. Instead, you often go with your "gut," which may involve a more implicit representation of the probability of rewarding outcomes based on past experience," Frank said.
The DARPP-32 and DRD2 genes control dopamine function in a region of the brain called the striatum, thought to be necessary for this kind of implicit reward learning. A third gene, COMT, did not predict long-term reward or punishment learning, but instead predicted a person's tendencies to change choice strategies after a single instance of negative feedback. Frank said this gene affects dopamine function in the prefrontal cortex of the brain, the area associated with conscious processing and working memory. This would be akin to switching from steak to salmon upon remembering your last experience with overdone steak.
The overall research program was designed to test a computer model that simulates the key roles of dopamine in reinforcement learning in different parts of the brain, as motivated by a body of biological research.
"The reason we looked at these three individual genes in the first place, out of a huge number of possible genes, is that we have a computer model that examines how dopamine mediates these kinds of reinforcement processes in the striatum and prefrontal cortex," Frank said. "The model makes specific predictions on how subtle changes in different aspects of dopamine function can affect behavior, and one way to get at this question is to test individual genes."
Among the evidence incorporated in the model and motivating the genetic study is research showing that bursts of dopamine production follow in the wake of unexpected rewards. Conversely, dopamine production declines when rewards are expected but not received.
To test their hypothesis, the researchers collected DNA from 69 healthy individuals who were asked to perform a computerized learning program. The volunteers were asked to pick one of two Japanese characters that appeared on a screen and were "rewarded" for a "correct" response, and "punished" for an "incorrect" one.
Frank said more research is needed to confirm that genetic effects are accompanied by brain-related changes in behavior. But, he said, the research offers insights into the genetic basis for learning differences and insights into improving human cognition and learning, both normal and abnormal.
"Understanding how dopaminergic variations affects learning and decision-making processes may have substantial implications for patient populations, such as (those with) Parkinson's disease, attention-deficit hyperactivity disorder (ADHD) and schizophrenia," Frank said. "The genetics might also help us identify individuals who might gain from different types of learning environments in the classroom."
Michael Frank's home page: http://www.u.arizona.edu/~mfrank/
Contact: 520-626-4787, email@example.com
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine