0093 Topographical Analysis of Sleep Spindles and Their Coordination with Slow Oscillations
Abstract Introduction Brain oscillations found during sleep are hypothesized to mediate sleep-dependent memory consolidation, by coordinating cortical-subcortical activity and enabling synaptic plasticity. In particular, sleep spindles (10-16Hz) density and coordination with slow oscillations (SOs, 0.5–1.5 Hz) have been shown to correlate with memory performance post-sleep. In this study, we characterize how spindles are organized on the electrode manifold, and their relation to SO topography. Methods We conducted a sleep-memory study where subjects learned word-pair associations in the morning and were tested in the evening and the next morning. Polysomnography was collected during the night. We detected sleep spindles at each electrode independently and study their basic biophysical properties (density, amplitude, frequency, duration) in light sleep (stage 2, S2) and deep sleep (slow wave sleep, SWS) separately, including their co-occurrence with SOs. We categorize spindles that are co-detected across electrodes within a short time window and study how properties change across groups. Results We find a gradual increase in average spindle frequency in the frontal-occipital axis, but no bimodality in frequency distribution. Furthermore, spindles paired to SOs (a minority in both stages) are shorter than non-paired spindles. We find that coordination between spindles and SO troughs is frequency but not amplitude selective; and differs between the two sleep stages. In S2, slow spindles precede SOs in frontal electrodes and fast spindles follow SOs in centro-posterior electrodes. Our clusters of spindle topography include a Frontal and a Posterior cluster. These clusters mirror the commonly considered slow-frontal and fast-posterior spindles, but contain less than half of all S2 spindles. Clustering identifies sub-types of spindle-SO complexes whose density is linked to memory performance. Conclusion Our study shows that specific sub-types of sleep oscillations, defined by their topography, support the coordination between spindles and SOs which could mediate cortical-subcortical dialogue during sleep. Support This work was supported by NIH grant (R01 AG046646) to Sara C. Mednick