AMPARs in Bergmann glia are necessary for preventing surplus CFs from producing synapses onto single Purkinje cells. Conversion of Ca2-permeable AMPARs into Ca2-impermeable receptors in Bergmann glia elicited morphological changes in fine glial processes wrapping Purkinje cell synapses, prolonged the kinetics of glutamatergic synaptic transmission, and caused multiple innervation of Purkinje cells by CFs. Thus, the morphology of glial processes and the synaptic activities would be interdependent. The Ca2-permeable AMPARs in glial cells probably play key roles in such interactions between glia and glutamatergic synapses.