title: Learning-induced multiple synapse formation in rat cerebellar cortex.
abstract: Strengthening of synaptic connections has been proposed to underlie information storage in the brain, and experience-dependent increases in synapse number have been observed. However, the effect of these new synapses on the specific connectivity, and thus function, of a given brain area remains largely unknown. We report here that motor learning specifically induces the formation of multiple synapses--two post-synaptic contacts at a single pre-synaptic varicosity--in the cerebellum. Rats undergoing motor learning had more multiple synapses (two Purkinje cell spines contacting a given parallel fiber varicosity) per Purkinje cell than did active or inactive controls. The formation of multiple synapses provides an additional connection between a given parallel fiber and Purkinje cell, thereby enhancing particular pathways, and may constitute a fundamental mechanism of neural encoding.
authors.affiliation: Department of Psychology, University of Illinois Urbana-Champaign, Urbana, IL, USA.
authors.forename: Kara D
authors.initials: KD
authors.lastname: Federmeier
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kleim
authors.forename: William T
authors.initials: WT
authors.lastname: Greenough
mesh_terms: D000818:Animals; D002525:Cerebellar Cortex / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009048:Motor Skills / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D011689:Purkinje Cells / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D013569:Synapses / Q000502:physiology*