Preparedness of Residents and Medical Students for the Transition to Competence by Design in Diagnostic Radiology Post-Graduate Medical Education.

Introduction: This needs assessment evaluated residents' and medical students' knowledge of Competence by Design (CBD), perceived benefits of and challenges or barriers to the transition to CBD for residents, and perceived overall preparedness for the transition to CBD in diagnostic radiology. Materials and Methods: All diagnostic radiology residents and medical students in Canada were eligible to participate in this national cross-sectional, questionnaire-based needs assessment. Knowledge of CBD was evaluated through participants' self-reported rating of their knowledge of CBD on a 5-point Likert scale. Perceived benefits of and challenges or barriers to the transition to CBD for residents were rank ordered. Participants' overall self-reported preparedness for the transition to CBD was assessed on a 5-point Likert scale. Data were summarized by descriptive statistics and bivariate analyses were conducted as appropriate. Results: Ninety-four residents (n = 77) and medical students (n = 17) participated in this needs assessment. Participants' mean ± standard deviation self-reported rating of their overall knowledge of CBD was 2.86 ± .94. Provision of meaningful feedback to learners and learners' ability to identify their own educational needs were among the highest ranked perceived benefits of the transition to CBD, while demands on time and increased frequency of evaluation were among the highest ranked perceived challenges or barriers to the transition to CBD. Few participants reported being either "prepared" (4.7%) or "somewhat prepared" (14.0%) for the transition to CBD. Conclusion: Preparedness for the transition to CBD in diagnostic radiology may be improved. Targeted interventions to augment the preparedness of residents and medical students should be considered.

Lesions of lateral habenula attenuate win-stay but not lose-shift responses in a competitive choice task.

Multiple neural systems contribute to choice adaptation following reinforcement. Recent evidence suggests that the lateral habenula (LHb) plays a key role in such adaptations, particularly when reinforcements are worse than expected. Here, we investigated the effects of bilateral LHb lesions on responding in a binary choice task with no discriminatory cues. LHb lesions in rats decreased win-stay responses but surprisingly left lose-shift responses intact. This same dissociated effect was also observed after systemic administration of d-amphetamine in a separate cohort of animals. These results suggest that at least some behavioural responses triggered by reward omission do not depend on an intact LHb.

Sex differences in rat decision-making: The confounding role of extraneous feeder sampling between trials.

Although male and female rats appear to perform differently in some tasks, a clear picture of sex differences in decision-making has yet to develop. This is in part due to significant variability arising from differences in strains and tasks. The aim of this study was to characterize the effects of sex on specific response elements in a reinforcement learning task so as to help identify potential explanations for this variability. We found that the primary difference between sexes was the propensity to approach feeders out of the task context. This extraneous feeder sampling affects choice on subsequent trials in both sexes by promoting a lose-shift response away from the last feeder sampled. Female rats, however, were more likely to engage in this extraneous feeder sampling, and therefore exhibited a greater rate of this effect. Once trials following extraneous sampling were removed, there were no significant sex differences in any of the tested measures. These data suggest that feeder approach outside of the task context, which is often not recorded, could produce a confound in sex-based differences of reinforcement sensitivity in some tasks.

Acute Δ-9-tetrahydrocannabinol administration in female rats attenuates immediate responses following losses but not multi-trial reinforcement learning from wins.

Δ-9-Tetrahydrocannabinol (THC) is the main psychoactive component of marijuana and has potent effects on decision-making, including a proposed reduction in cognitive flexibility. We demonstrate here that acute THC administration differentially affects some of the processes that contribute to cognitive flexibility. Specifically, THC reduces lose-shift responding in which female rats tend to immediately shift choice responses away from options that result in reward omission on the previous trial. THC, however, did not impair the ability of rats to flexibly bias responses toward feeders with higher probability of reward in a reversal task. This response adaptation developed over several trials, suggesting that THC did not impair slower forms of reinforcement learning needed to choose among options with unequal utility. This dissociation of THC's effects on innate/rapid and learned/gradual decision-making processes was unexpected, but is supported by emerging evidence that lose-shift responding is mediated by neural mechanisms distinct from those involved in other forms of reinforcement learning. The present data suggest that, at least in some tasks, the apparent reductions in cognitive flexibility by THC may be explained by the immediate effects on loss sensitivity, rather than impairments of all processes used for choice adaptation.

Opposing effects of acute and chronic d-amphetamine on decision-making in rats.

Amphetamine and other drugs of abuse have both short-term and long-lasting effects on brain function, and drug sensitization paradigms often result in chronic impairments in behavioral flexibility. Here we show that acute amphetamine administration temporarily renders rats less sensitive to reward omission, as revealed by a decrease in lose-shift responding during a binary choice task. Intracerebral infusions of amphetamine into the ventral striatum did not affect lose-shift responding but did increase impulsive behavior in which rats chose to check both reward feeders before beginning the next trial. In contrast to acute systemic and intracerebral infusions, sensitization through repeated exposure induced long-lasting increased sensitivity to reward omission. These treatments did not affect choices on trials following reward delivery (i.e. win-stay responding), and sensitization increased spine density in the sensorimotor striatum. The dichotomous effects of amphetamine on short-term and long-term loss sensitivity, and the null effect on win-stay responding, are consistent with a shift of behavioral control to the sensorimotor striatum after drug sensitization. These data provide a new demonstration of such a shift in a novel task unrelated to drug administration, and suggests that the dominance of sensorimotor control persists over many hundreds of trials after sensitization.