Depression is one of the most common mental disorders worldwide, however, its etiology and pathophysiology remain to be elucidated. Brain imaging and postmortem studies provide evidence for decreased brain volume and reduced number of dendritic spines in cortical and limbic regions, suggestive of aberrant neural and synaptic plasticity associated with depression. Depression-related neuroplasticity is thought to be mediated in part by environmental stressors, in addition to individual genetic factors. Indeed, chronically stressed rodents show alterations in dendritic length and spine density. Thus, chronic stress-induced aberrant neural plasticity may have a causal role in the development of depression.
 Neural plasticity refers to sustained modifications in synaptic structure and function that require de novo gene expression. The control of gene expression in the brain is essential for the maintenance of both stable and maladaptive neural alterations in response to environmental cues such as stress. Therefore, a current hypothesis of depression pathophysiology is that chronic stress-induced aberrant gene expression in the brain leads to maladaptive neuroplastic alterations that may predispose an individual to depression.
 Recent evidence suggests that post-transcriptional regulation of gene expression by non-coding RNAs play an important role in regulating neural and synaptic plasticity. There are two main groups of non-coding RNAs: small non-coding RNAs and long non-coding RNAs. MicroRNAs belong to a class of small non-coding RNAs that can cleave or repress the translation of target mRNAs by binding to 3' untranslated regions. Importantly, several lines of evidence suggest a role of microRNAs in behavioral responses to stress, neural plasticity, depression, and antidepressant drug action.
 In this review, I briefly summarize the contributions of non-coding RNAs to neural plasticity. I also discuss evidence that chronic stress-mediated changes in gene expression through non-coding RNAs have a pivotal role in neural plasticity associated with the development of stress vulnerability, and the pathophysiology of depression.
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