It has been suggested that the initiation and maintenance of cocaine self-administration (SA) is critically dependent on the dopaminergic (DA) projection to the medial prefrontal cortex (mPFC). Evidence for this hypothesis has been obtained from intracranial SA of cocaine, but a role of the mPFC in IV cocaine SA has not been established. The present experiment investigated the effect of destruction of DA-containing terminals in the mPFC on the rate and pattern of IV cocaine SA. Rats were trained to self-administer cocaine during daily 3-h sessions. After stable response patterns were obtained, the rats received either bilateral injections of 6-hydroxydopamine (6-OHDA) into the mPFC, or sham operations. The lesions did not affect either the rate or pattern of IV cocaine SA, despite producing substantial DA depletions in the mPFC. Thus, the mPFC does not appear to be a critical substrate for the maintenance of IV cocaine SA. The 6-OHDA lesions of the mPFC resulted in an apparent increase in DA turnover in both the striatum and the nucleus accumbens, suggesting that DA terminals in the mPFC may have an inhibitory influence on the activity of subcortical DA projections.

The involvement of dopaminergic (DA) and serotonergic (5-HT) systems in circling was assessed by determining the neurochemical correlates of circling induced and maintained by two different schedules of water reinforcement. The conditioned circling paradigm was employed in an attempt to replicate reports that levels of DA and 3,4-dihydroxyphenylacetic acid (DOPAC) were increased in the striatum and nucleus accumbens septi (NAS) contralateral to the direction of circling. Rats trained to circle using a continuous schedule of reinforcement did not exhibit any changes in concentrations of DA, DOPAC, or homovanillic acid (HVA). Bilateral increases in 5-HT concentrations were observed in the striatum. Use of an intermittent schedule of reinforcement (FR-2) produced higher rates of circling. In rats maintained on the FR-2 schedule, no changes in DA or its metabolites were observed in the striatum. The ratio of HVA to DA was, however, increased bilaterally, suggesting a bilateral augmentation of DA utilization. Concentrations of DA were lower in the NAS contralateral to direction of turning. While NAS levels of HVA were elevated bilaterally when compared to non-circling controls, HVA was lower in the NAS contralateral to the direction of circling. DA utilization, as estimated by HVA: DA ratios, was increased bilaterally in the NAS. None of the measures of DA activity within the olfactory tubercle (OT) were influenced by circling. Turnover of 5-HT, as estimated by the ratio of 5-HT to 5-hydroxyindoleacetic acid (5-HIAA), was increased bilaterally in the striatum, NAS, and OT.(ABSTRACT TRUNCATED AT 250 WORDS)

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Many active learning techniques have been used and described over the years, including team-based learning (TBL). While this technique is well established, it is only recently that analyses that compare it to other teaching techniques have been reported. In this paper, we evaluate the impact of team-based learning on two major concerns for computer science instructors: the drop/attrition rates, and students' success in CS1. The results show some major improvements both in terms of the drop rate and students' success, as measured by final exam grades. For example, the number of students obtaining 50% or more on the final exam has increased from 54% to 75.5%. Moreover, the drop rate has decreased from more than 30% to 6.4%.

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