The Schema Effect and Sleep-dependent Memory Consolidation

Hennies, N. , Lambon Ralph, M. A. , Cousins, J. & Lewis, P. A.

University of Manchester, UK

The acquisition of knowledge is more effective if an associative schema into which new information is incorporated is present. This advantage for schema-linked learning is thought to be driven by accelerated consolidation mechanisms. If sleep-dependent memory consolidation is involved in this process remains unclear. Here, we explore the interaction between sleep-dependent consolidation and schema-linked learning. After establishing a schema, participants encoded new facts that were either related to the schema or unrelated, in two sessions, 24 hours apart. Overnight sleep was polysomnographically monitored, and memory was tested in an MRI scanner directly after the second encoding. Participants showed a greater advantage for schema-linked learning after consolidation (p<0.001). Interestingly, spindle density predicted an increase in this interaction (r=0.6, p=0.006), while a greater percentage of stage 4 sleep predicted a decrease (r=-0.62, p=0.003). A median split revealed that more spindles were associated with less decay of schema-related memories (p=0.003). Less S4 sleep was associated with a greater decay of non-schema memories (p=0.002). fMRI analysis is ongoing. Our results provide initial evidence for an association between the advantage for schema-linked learning and sleep, and suggest that deep sleep and sleep spindles may play differential roles.