GPER1s are estrogen-sensitive receptors mediating the rapid non-genomic actions of estrogen. GPER1s are enriched in the brain and is highly expressed at synapses. GPER1s rapidly regulate hippocampal dendritic morphology and synaptic plasticity. Higher brain functions such as learning and memory are influenced by GPER1s. The neuroprotective actions of estrogens are linked to GPER1 activation.