up a large portion of the genome (Carninci et al., 2005; Consortium, 2012; Farris et al., 2015a), and distinct ncRNA regulatory mechanisms in brain are thought to influence the development and progression of psychiatric disorders (Kocerha et al., 2015; Sartor et al., 2012), including alcoholism (Farris and Mayfield, 2014). MicroRNAs (miRNAs; ~17–24 nucleotides) are one class of ncRNAs that are known to regulate the expression of many genes by binding to miRNA-regulation elements in their transcriptional targets. This direct targeting can result in suppression of translation, degradation of the targeted mRNA transcript, or even increased mRNA translation, resulting in enhanced expression of target genes (Breving and Esquela-Kerscher, 2010; Filipowicz et al., 2008; Vasudevan et al., 2007). miRNAs have important roles in multiple biological processes including neuronal differentiation, brain development, synapse formation and plasticity, and neurodegeneration (Fiorenza and Barco, 2016). In addition, miRNAs have roles in aberrant biological processes that underlie neurodegenerative diseases (e.g., Alzheimer’s and Parkinson’s disease) and neuropsychiatric illnesses (e.g., schizophrenia, bipolar disorder), as well as the cellular adaptations induced by drugs of abuse (e.g., nicotine, cocaine, opioids, alcohol) (Miranda et al., 2010; Nunez and Mayfield, 2012).
