Cerebellar damage impairs long-term but not short-term sensorimotor memory

Abstract

AbstractThe cerebellum is critical for sensorimotor learning. The specific contribution that it makes, however, remains unclear. Inspired by the classic finding that, for declarative memories, medial temporal lobe structures provide a gateway to the formation of long-term memory but are not required for short-term memory, we hypothesized that, for sensorimotor memories, the cerebellum may play an analogous role. We thus dissected the memories formed during sensorimotor learning into short-term temporally-volatile and longer-term temporally-persistent components in individuals with severe ataxia from cerebellar degeneration. Remarkably, we find that these individuals display dramatically reduced levels of temporally-persistent sensorimotor memory that leads to long-term retention, despite spared and even elevated levels of temporally-volatile sensorimotor memory that does not. In particular, we find both impairment that systematically increases with memory window duration over shorter memory windows (<12 sec) and near-complete impairment of memory maintenance over longer memory windows (>25 sec). This dissociation uncovers a new role for the cerebellum as a gateway for the formation of long-term but not short-term sensorimotor memories, reveals distinct neural substrates for short-term and long-term sensorimotor memory, and explains both newly-identified trial-to-trial differences and long-standing study-to-study differences in the effects of cerebellar damage on sensorimotor learning ability.