Adolescence coincides with symptomatic onset of several psychiatric illnesses including schizophrenia and addiction. Excess limbic dopamine activity has been implicated in these vulnerabilities. We combined molecular and dynamic indices of dopamine neurotransmission to assess dopamine function in adolescent rats in two functionally distinct striatal subregions: nucleus accumbens (NAc) and dorsal striatum (DS). In adolescents, we find an overall reduction in dopamine availability selective to the DS. Dopamine release in the DS, but not in the NAc, was less responsive to amphetamine in adolescents compared to adults. The dopamine transporter (DAT) inhibitor, nomifensine, similarly inhibited basal and amphetamine-induced dopamine release in either regions of both the age groups, suggesting that the reduced effectiveness of amphetamine is not due to differences in DAT function. Furthermore, DAT and vesicular monoamine transporter-2 expressions were similar in the DS and NAc of adolescent rats. In contrast, expression of tyrosine hydroxylase (TH) was reduced in the DS, but not in the NAc, of adolescents compared to adults. Behaviorally, adolescents were less sensitive to amphetamine but more sensitive to a TH inhibitor. These data indicate that, in contrast to the general notion that dopamine is hyperactive in adolescents, there is diminished presynaptic dopamine activity in adolescents that is selective to the DS and may result from attenuated TH activity. Given recent reports of altered dopamine activity in associative/dorsal striatum of individuals at a clinically high risk of psychosis, our data further support the idea that dorsal, as opposed to ventral, regions of the striatum are a locus of vulnerability for psychosis.

Over the last two decades, there have been numerous technical and methodological advances available to clinicians and researchers to better understand attention deficit hyperactivity disorder (ADHD) and its etiology. Despite the growing body of literature investigating the disorder’s pathophysiology, ADHD remains a complex psychiatric disorder to characterize. This chapter will briefly review the literature on ADHD, with a focus on its history, the current genetic insights, neurophysiologic theories, and the use of neuroimaging to further understand the etiology. We address some of the major concerns that remain unclear about ADHD, including subtype instability, heterogeneity, and the underlying neural correlates that define the disorder. We highlight that the field of ADHD is rapidly evolving; the descriptions provided here will hopefully provide a sturdy foundation for which to build and improve our understanding of the disorder.

Here, we use recent U.S. National Institutes of Health (NIH) data to document trends in the NIH-funded workforce over time. Consistent with previous studies that were initiated by NIH, we find that the number of scientists funded on competing R01-equivalent (R01 Eq.) and research project grants (RPGs) increased 2-5% per year between 2009 and 2016. Primary beneficiaries of this growth were experienced investigators (Exp), whereas the share of funding awarded to early-stage investigators (ESIs) and new investigators (NIs) declined. The decline occurred even after NIH instituted the New and Early-Stage Investigator policy in 2009. When we evaluate the investigator pool, we find that women and racial and ethnic minorities represent a higher percentage of NIs and ESIs relative to Exp. Thus, trends of diminishing support for NIs and ESIs may negatively impact the diversity of the current and future biomedical research workforce. We find some recent gains among women and Hispanics as part of the applicant and awardee pool for both R01 Eq. and RPGs, but significant, large gaps persist among nationally underrepresented racial minorities. Our findings suggest a need to prioritize investments and support of ESIs and NIs, groups in which women and racial and ethnic minorities represent a larger proportion of the applicant pool, to enhance diversity in the NIH-funded workforce.-Nikaj, S., Roychowdhury, D., Lund, P. K., Matthews, M., Pearson, K. Examining trends in the diversity of the U.S. National Institutes of Health participating and funded workforce.