CaV1.3 channel blockade in the extended amygdala has a delayed effect on the reward efficacy of medial forebrain bundle stimulation.

Previous work in our laboratory has shown that stimulating D2 dopamine receptors in the central sublenticular extended amygdala (SLEAc) can render medial forebrain bundle (MFB) stimulation less rewarding. One of the many ways in which D2 stimulation could affect the activity status of SLEAc neurons is by indirectly blocking calcium ion (Ca2+) influx through CaV1.3 channels. He we directly investigate the effects of blocking CaV1.3 channels on the rewarding effect of MFB stimulation. In experiment one, CaV1.3 blockade with the phenylalkylamine verapamil (2.5 and 5.0µg) or the benzothiazepine diltiazem (5.0 and 10.0µg) did not significantly decrease MFB stimulation's reward efficacy relative to injections of saline. However, there were indications of an unanticipated 24-h-delayed effect of the higher dose of diltiazem - injected ipsilateral to the stimulation site - on the stimulation pulse frequency required to maintain half-maximal response rates ("required frequency"). Experiment two focused on and tracked the time course of this effect. Injections of 10µg of diltiazem decreased required frequency significantly more than did saline injections 24h after injection but not immediately after injection. Required frequency values returned to baseline levels within 48h after injection. This time course is consistent with cellular processes that regulate the insertion of GABA-A receptors in neural membranes. GABA-A-mediated neural communication is implicated in maintaining basal forebrain medium spiny neurons in an excitable state. Therefore, these results may indicate that sustaining SLEAc neurons in an excitable state may be important for MFB stimulation to retain its rewarding properties.

Is Performance-Based Progress Testing in Psychiatry Feasible?

OBJECTIVE: The aim of this study was to explore if competency-based progress tests for postgraduate psychiatry are reliable, if they are able to discriminate trainees at different levels of training, and if they are able to demonstrate improvement of trainees' skills from 3 years of data. METHODS: Psychiatry trainees in the North Western Deanery, UK, were invited to participate in the annual progress test. The progress test simulated the Clinical Assessment of Skills and Competencies (CASC) exam, the final postgraduate examination for psychiatry trainees. The sum of global scores from all stations for each candidate was used for statistical analysis. Cronbach's alpha was used to calculate the interstation reliability. Analysis of variance (ANOVA) was used to explore if the progress test could discriminate between the three levels of trainees each year. Student's t test was used to explore if there was improvement and development of skills as a cohort progressed; ANOVA was used for the cohort with 3 years of data. RESULTS: The progress test is more likely to be reliable (alpha ≥ 0.8) when 12 stations are used. ANOVA revealed significantly improved scores with increasing level of seniority in 2012, with a mean total score increasing from 23.1 to 31.3 (p = 0.008) and 36.9 to 46.6 in 2013 (p = 0.004). In 2014, this effect was not observed, with a mean decreasing from 42.4 to 41.3. Over time, two cohorts demonstrated improving mean scores with Student's t tests from 26.4 to 32.4 (p = 0.01) and 26.9 to 42.6 (p = 0.01). The third cohort did not demonstrate a difference over time, with mean scores 23.1, 27.6, and 25.9 over 3 years. CONCLUSIONS: It is not conclusive if the progress test can accurately distinguish between trainee seniority or assess progress over time; possible explanations for non-significant results and further avenues of enquiry are discussed.