The Acute and Chronic Effects of Ketamine as Revealed by Noninvasive Brain Imaging

Ketamine, a noncompetitive N-methyl-d-aspartate receptor antagonist, has been used in the experimental psychosis model for a long time. The recreational use of ketamine-induced acute and severe impairments of cognitive functions and further structural deficiency are receiving increasing attention. Recently, the antidepressant effect of a single subanesthesia dose of ketamine has been repeatedly reported and may indicate a novel, rapid-acting antidepressant agent with a mechanism that is distinct from currently available medications. Considering the complex series of biological processes and multiple mechanisms are involved after ketamine administration, it will be important to have a better understanding of the temporal dynamics of neuronal activities induced by ketamine and their regional specificity. In this chapter, we summarize findings on the use of ketamine and provide a critical overview of the current knowledge on the underlying mechanisms of action of ketamine, by combining evidence across different magnetic resonance imaging modalities, time frames, and dosage schemes. We then suggest some future research directions for the investigation of the fast-acting antidepressant effect of ketamine