The recent reports that scopolamine has antidepressant effects in humans has raised the hope that this antimuscarinic drug represents an improvement over the serotonergic and noradrenergic reuptake blockers that have formed the basis for antidepressant medication for decades. Scopolamine's effects had a rapid onset of action, and were quite long lasting, giving them considerable advantage over previous medications.

Saliva performs a number of extremely important biological functions that are instrumental in maintaining oral health. It has been estimated that more than 5 million people in the US suffers from salivary gland dysfunction. Secretion of saliva is driven by concerted activities of a number of ion channels and transporters. Although, it is believed that calcium is the primary intracellular factor that regulates fluid secretion, the molecular mechanism involved in the regulation of cytosolic calcium is not clearly understood.

This competing renewal of our longitudinal project proposes to elucidate mechanisms driving the initiationand progression of substance use is consistent with NIDA and NIMH's recently outlined strategic plans (NIDA,2016; NIH CRAN, 2015; NIMH, 2015) prioritizing research on the period between adolescence and youngadulthood. Defining features of typical adolescent development are increases in sensation seeking followed bymore gradual increases in impulse control (described by the Dual Systems model).