Changes in the number of postsynaptic AMPA receptors are believed to underlie long-term potentiation and long-term depression in cellular models of learning and memory. Furthermore, dysfunctions in AMPA receptors leading to imbalances between excitatory and inhibitory synapses are thought to underlie certain neuronal disorders such as epilepsy, Alzheimer's disease, depression and schizophrenia. Despite an accumulation of basic research on AMPA receptors suggesting substantial potential of these receptors as a therapeutic target, clinical translation has been limited. This could be attributed to the lack of technology to visualize AMPA receptors in the living human brain. Thus, there is a need for a technology to visualize AMPA receptors in the living human brain to further elucidate the molecular and circuit bases of neuronal diseases and to develop novel diagnostic and therapeutic options. PET is widely used in clinical diagnosis. Although several compounds have been developed as potential PET tracers for AMPA receptors, there is currently no radiotracer suitable for in vivo PET imaging of AMPA receptors. Here we developed a new AMPA receptor PET tracer named [11C]K-2, which is suitable for visualizing AMPA receptors in the human brain.