Cerebellar Theta-Burst Stimulation Impairs Memory Consolidation in Eyeblink Classical Conditioning

Associative learning of sensorimotor contingences, as it occurs in eyeblink classical conditioning (EBCC), is known to involve the
cerebellum, but its mechanism remains controversial. EBCC involves a sequence of learning processes which are thought to occur
in the cerebellar cortex and deep cerebellar nuclei. Recently, the extinction phase of EBCC has been shown to be modulated after
one week by cerebellar continuous theta-burst stimulation (cTBS). Here, we asked whether cerebellar cTBS could affect retention
and reacquisition of conditioned responses (CRs) tested immediately after conditioning. We also investigated a possible lateralized
cerebellar control of EBCC by applying cTBS on both the right and left cerebellar hemispheres. Both right and left cerebellar cTBSs
induced a statistically significant impairment in retention and new acquisition of conditioned responses (CRs), the disruption effect
being marginally more effective when the left cerebellar hemisphere was stimulated. These data support a model in which cTBS
impairs retention and reacquisition of CR in the cerebellum, possibly by interfering with the transfer of memory to the deep
cerebellar nuclei.