Figure 2. Mechanisms for neural activity-mediated remodeling of CF-to-PC synapses during postnatal cerebellar development.

( A) Ca ²⁺ influx through P/Q-VDCC into PCs triggers strengthening of a single CF at ~P3 to ~P7 (functional differentiation). ( B) Ca ²⁺ influx through P/Q-VDCC promotes translocation of the single strong CF to the PC dendrite and at the same time eliminates CF synapses from the PC soma at ~P7 to ~P11 (early phase of CF elimination). GABAergic inhibition from BC to PC inhibits Ca ²⁺ influx and thereby regulates elimination of somatic CFs from ~P10. ( C) mGluR1 to PKCγ signaling and Arc activated by Ca ²⁺ influx through P/Q-VDCC promotes elimination of somatic CF synapses at ~P12 to ~P17 (late phase of CF elimination). ( D) mGluR1 and its downstream signaling in PCs promote elimination of PF synapses from proximal portions of PC dendrites from ~P15 to ~P30 (PF synapse elimination). BC, basket cell; CF, climbing fiber; mGluR1, metabotropic glutamate receptor subtype 1; PC, Purkinje cell; PF, parallel fiber; PKCγ, protein kinase Cγ; VDCC, voltage-dependent Ca ²⁺ channel.