Rostrolateral Prefrontal Cortex and Individual Differences in Uncertainty-Driven Exploration

SummaryHow do individuals decide to act based on a rewarding status quo versus an unexplored choice that might yield a better outcome? Recent evidence suggests that individuals may strategically explore as a function of the relative uncertainty about the expected value of options. However, the neural mechanisms supporting uncertainty-driven exploration remain underspecified. The present fMRI study scanned a reinforcement learning task in which participants stop a rotating clock hand in order to win points. Reward schedules were such that expected value could increase, decrease, or remain constant with respect to time. We fit several mathematical models to subject behavior to generate trial-by-trial estimates of exploration as a function of relative uncertainty. These estimates were used to analyze our fMRI data. Results indicate that rostrolateral prefrontal cortex tracks trial-by-trial changes in relative uncertainty, and this pattern distinguished individuals who rely on relative uncertainty for their exploratory decisions versus those who do not.Video Abstrac

Providing competency-based family medicine residency training in substance abuse in the new millennium: a model curriculum

<p>Abstract</p> <p>Background</p> <p>This article, developed for the Betty Ford Institute Consensus Conference on Graduate Medical Education (December, 2008), presents a model curriculum for Family Medicine residency training in substance abuse.</p> <p>Methods</p> <p>The authors reviewed reports of past Family Medicine curriculum development efforts, previously-identified barriers to education in high risk substance use, approaches to overcoming these barriers, and current training guidelines of the Accreditation Council for Graduate Medical Education (ACGME) and their Family Medicine Residency Review Committee. A proposed eight-module curriculum was developed, based on substance abuse competencies defined by Project MAINSTREAM and linked to core competencies defined by the ACGME. The curriculum provides basic training in high risk substance use to all residents, while also addressing current training challenges presented by U.S. work hour regulations, increasing international diversity of Family Medicine resident trainees, and emerging new primary care practice models.</p> <p>Results</p> <p>This paper offers a core curriculum, focused on screening, brief intervention and referral to treatment, which can be adapted by residency programs to meet their individual needs. The curriculum encourages direct observation of residents to ensure that core skills are learned and trains residents with several "new skills" that will expand the basket of substance abuse services they will be equipped to provide as they enter practice.</p> <p>Conclusions</p> <p>Broad-based implementation of a comprehensive Family Medicine residency curriculum should increase the ability of family physicians to provide basic substance abuse services in a primary care context. Such efforts should be coupled with faculty development initiatives which ensure that sufficient trained faculty are available to teach these concepts and with efforts by major Family Medicine organizations to implement and enforce residency requirements for substance abuse training.</p

The expanding role of dopamine.

Evidence increasingly suggests that dopaminergic neurons play a more sophisticated role in predicting rewards than previously thought

How instructed knowledge shapes adaptive learning

We previously published results of a study examining how instructions shape aversive reversal learning (Atlas et al., 2016). Our original paper measured how instructions and learning influence on expected value, and assumed that learning rates remain stable over time. We found that instructions caused immediate reversals in corticostriatal systems, while value signals in the amygdala required reinforcement in order to update. However, our paradigm was originally designed to measure adaptive learning, and to test whether previously observed neural dissociations in the encoding of associability and prediction error i) replicate in the context of repeated reversals and ii) are modulated with instructions. Here, we present reanalyses using a hybrid model, in which associability gates learning. In our Uninstructed Group, we replicate previous dissociations (Li et al., 2011) such that the striatum tracks prediction error while the amygdala tracks associability. Comparisons with an Instructed Group reveal that instructions update expected value and striatal prediction error, while amygdala associability updates based on feedback alone, irrespective of instruction. This work adds to a growing body of literature on adaptive learning and provides new results that suggest that instructions have dissociable effects on prediction error and associability

How instructed knowledge shapes adaptive learning

We previously published results of a study examining how instructions shape aversive reversal learning (Atlas et al., 2016). Our original paper measured how instructions and learning influence on expected value, and assumed that learning rates remain stable over time. We found that instructions caused immediate reversals in corticostriatal systems, while value signals in the amygdala required reinforcement in order to update. However, our paradigm was originally designed to measure adaptive learning, and to test whether previously observed neural dissociations in the encoding of associability and prediction error i) replicate in the context of repeated reversals and ii) are modulated with instructions. Here, we present reanalyses using a hybrid model, in which associability gates learning. In our Uninstructed Group, we replicate previous dissociations (Li et al., 2011) such that the striatum tracks prediction error while the amygdala tracks associability. Comparisons with an Instructed Group reveal that instructions update expected value and striatal prediction error, while amygdala associability updates based on feedback alone, irrespective of instruction. This work adds to a growing body of literature on adaptive learning and provides new results that suggest that instructions have dissociable effects on prediction error and associability

Instructed knowledge shapes feedback-driven aversive learning in striatum and orbitofrontal cortex, but not the amygdala.

Socially-conveyed rules and instructions strongly shape expectations and emotions. Yet most neuroscientific studies of learning consider reinforcement history alone, irrespective of knowledge acquired through other means. We examined fear conditioning and reversal in humans to test whether instructed knowledge modulates the neural mechanisms of feedback-driven learning. One group was informed about contingencies and reversals. A second group learned only from reinforcement. We combined quantitative models with functional magnetic resonance imaging and found that instructions induced dissociations in the neural systems of aversive learning. Responses in striatum and orbitofrontal cortex updated with instructions and correlated with prefrontal responses to instructions. Amygdala responses were influenced by reinforcement similarly in both groups and did not update with instructions. Results extend work on instructed reward learning and reveal novel dissociations that have not been observed with punishments or rewards. Findings support theories of specialized threat-detection and may have implications for fear maintenance in anxiety