Abstract Synapses are the basis of neuronal communication and plasticity. Decades of research in reduced preparations have revealed fundamental principles of neuronal transmission and synaptic plasticity. This work identified key molecular constituents of synapses and pre- and postsynaptic mechanisms underlying activity dependent changes in synaptic transmission. Now, technological advances in optical manipulation and read-out technologies have opened the door to studying the role of synapses in-vivo. Thus, allowing dissection of synapse function from neuronal circuits to cognition. Synaptic plasticity is integral to development and experience-dependent changes in the brain. While there have been attempts to link synaptic plasticity mechanisms discovered in reduced preparations to in-vivo function such as memory formation, important challenges and questions remain. How do the longer time scales of behavioral memory formation and the corresponding in-vivo synaptic changes relate to the relatively short time scales of synaptic transmission and plasticity? What role does synaptic plasticity play in the formation and updating of large-scale neural networks (internal models) underlying cognitive processes involving prospective planning and inference? How is information maintained in neural circuits in the face of dynamic and changing synaptic architecture in the developing and adult brain? How do non-neuronal cells such as astrocytes and microglia contribute to synaptic function and plasticity? When and how can our understanding of basic mechanisms of synaptic function be used to develop treatments for debilitating psychiatric disorders? Coming out of the global coronavirus pandemic this meeting is particularly relevant as the usual lines of international scientific communication and collaboration were cut and research endeavors became isolated. Trainees and junior faculty were particularly hard hit during this time as their ability to network and collaborate across borders was severely curtailed. In-person, face-to-face scientific interaction and discussion is needed now more than ever. Our meeting will bring together scientists from the US and Japan at many stages of career development to re-energize global scientific exchange between our two countries. Our goals are to share in recent scientific successes and, most importantly, identify new directions for the field which will spark innovation and collaboration.