AMPA Receptors Exist in Tunable Mobile and Immobile Synaptic Fractions In Vivo.

AMPA receptor (AMPAR) mobility within synapses has been extensively studied in vitro However, whether similar mobility properties apply to AMPARs in vivo has yet to be determined. Here, we use two-photon fluorescence recovery after photobleaching (FRAP) to study AMPAR mobility within individual dendritic spines in live animals using an overexpression vector. We demonstrate the existence of mobile and immobile fractions of AMPARs across multiple cortical regions and layers. Additionally, we find that AMPAR mobility can be altered in vivo in response to administration of corticosterone, a condition that mimics exposure to stress.