The mesolimbic dopamine (DA) system has been implicated in drug reward, locomotor sensitization, and responding for reward-related stimuli [termed conditioned reinforcers (CR)]. Here, we investigated the effect of brain-derived neurotrophic factor (BDNF), which enhances the survival and function of dopaminergic neurons, on stimulant-induced locomotor sensitization and responding for CR. In experiment 1, BDNF was infused into the nucleus accumbens (NAc) or ventral tegmental area over 2 weeks via chronically implanted minipumps (1-2.5 microgram/d), and the psychomotor stimulant effects of cocaine (5-15 mg/kg, i.p.) were studied. We found that BDNF enhanced the initial stimulant effects of cocaine and seemed to facilitate the development of sensitization to repeated cocaine doses. In experiment 2, we studied the effects of intra-NAc BDNF infusions on responding for CR. BDNF-treated rats showed twice as many CR responses compared with controls when saline was first administered. BDNF enhanced responding on the CR lever more than four times that seen in control animals after a cocaine injection (10 mg/kg, i.p.). The enhanced response to cocaine in BDNF-treated animals persisted for more than a month after the BDNF infusions had stopped, indicating long-lasting changes in the mesolimbic DA system caused by BDNF administration. In experiment 3, we examined locomotor sensitization to cocaine in heterozygous BDNF knock-out mice and found that the development of sensitization was delayed compared with wild-type littermates. These results demonstrate the profound effects of BDNF on the enhancement of both cocaine-induced locomotion and facilitation of CR and suggest a possible role for BDNF in long-term adaptations of the brain to cocaine.

IMPORTANCE While the relationship between resident work hours and patient safety has been extensively studied, little research has evaluated the role of attending physician supervision on patient safety. OBJECTIVE To determine the effect of increased attending physician supervision on an inpatient resident general medical service on patient safety and educational outcomes. DESIGN, SETTING, AND PARTICIPANTS This 9-month randomized clinical trial performed on an inpatient general medical service of a large academic medical center used a crossover design. Participants were clinical teaching attending physicians and residents in an internal medicine residency program. INTERVENTIONS Twenty-two faculty provided either (1) increased direct supervision in which attending physicians joined work rounds on previously admitted patients or (2) standard supervision in which attending physicians were available but did not join work rounds. Each faculty member participated in both arms in random order. MAIN OUTCOMES AND MEASURES The primary safety outcome was rate of medical errors. Resident education was evaluated via a time-motion study to assess resident participation on rounds and via surveys to measure resident and attending physician educational ratings. RESULTS Of the 22 attending physicians, 8 (36%) were women, with 15 (68%) having more than 5 years of experience. A total of 1259 patients (5772 patient-days) were included in the analysis. The medical error rate was not significantly different between standard vs increased supervision (107.6; 95% CI, 85.8-133.7 vs 91.1; 95% CI, 76.9-104.0 per 1000 patient-days; P = .21). Time-motion analysis of 161 work rounds found no difference in mean length of time spent discussing established patients in the 2 models (202; 95% CI, 192-212 vs 202; 95% CI, 189-215 minutes; P = .99). Interns spoke less when an attending physician joined rounds (64; 95% CI, 60-68 vs 55; 95% CI, 49-60 minutes; P = .008). In surveys, interns reported feeling less efficient (41 [55%] vs 68 [73%]; P = .02) and less autonomous (53 [72%] vs 86 [91%]; P = .001) with an attending physician present and residents felt less autonomous (11 [58%] vs 30 [97%]; P < .001). Conversely, attending physicians rated the quality of care higher when they participated on work rounds (20 [100%] vs 16 [80%]; P = .04). CONCLUSIONS AND RELEVANCE Increased direct attending physician supervision did not significantly reduce the medical error rate. In designing morning work rounds, residency programs should reconsider their balance of patient safety, learning needs, and resident autonomy.

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To better understand the impact and generalizability of clinical coaching, a larger, longitudinal study is required to look at patient and provider outcomes in detail. Further refinement of the SCA role to meet faculty needs is needed and could include faculty development.