Schedule of Events | Symposia

Human sleep spindles are directed by excitatory non-invasive brain stimulation

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Jude Thom¹ (jude.thom@linacre.ox.ac.uk), Bernhard Staresina¹; ¹Department of Experimental Psychology, University of Oxford

Brain activity during sleep is important for consolidating memory. Sleep spindles are bursts of activity linked to memory, intelligence, and neurological disorders. Hippocampal-neocortical synchronization increases around spindles, as do biomarkers of synaptic plasticity. This suggests spindles may play a mechanistic role in memory consolidation during sleep. Recent work shows spindles track cortical regions engaged in a memory task before sleep. Overlap between the task activity and spindle activity predicted memory benefits of sleep. If spindles are indeed guided by endogenous excitability before sleep, can we direct spindles by exogenously exciting regions with localised non-invasive brain stimulation? Moreover, does this influence functionally localised memory consolidation during sleep? We used a within-subject design to test the effect of excitatory transcranial direct current stimulation (tDCS) on spindles. 19 participants learned a one-handed motor task before having excitatory tDCS applied to left or right motor cortex. We then recorded sleep and spindle rates with electroencephalography and compared the spatial distribution of spindles alongside motor skill consolidation between sessions with left excitation and right excitation. Our results show tDCS successfully modulated spindle rates, with more spindles at excited sites. Importantly, stimulation site had no effect on slow oscillations. However, stimulation did not influence motor skill consolidation. These results suggest spindle topographies are neither hard-wired nor random but are influenced by cortical excitability before sleep, which can be modified with external stimulation. This lays the groundwork for tDCS to be used to study the cognitive and physiological role of regional spindles in memory consolidation during sleep.

Topic Area: METHODS: Electrophysiology