In a single blind randomized parallel group design, we will evaluate the whether a single dose of GLYX-13 vs. placebo increases cognitive performance on tasks of learning, declarative memory, and working memory, and associated task-related increases in blood oxygen level-dependent (BOLD) activation in hippocampus and dorsolateral prefrontal cortex, respectively. Positive findings will provide biomarker evidence for GLYX-13 effects on neural systems underlying these cognitive processes.