Intra-synapse-type and inter-synapse-type relationships between synaptic size and AMPAR expression

► The size of synapse and the AMPAR number/density are anatomically examined. ► The AMPAR number positively correlates with the synapse size in all connections. ► The average AMPAR density in each connection negatively correlates with the average synapse size. ► The variability of AMPAR number in each connection positively correlates with the average synapse size. ► Synaptic connections with low average AMPAR density have mosaic AMPAR distribution.