Slow-oscillatory Transcranial Direct Current Stimulation Modulates Memory in Temporal Lobe Epilepsy by Altering Sleep Spindle Generators: A Possible Rehabilitation Tool

• Published in: Brain stimulation Vol. 8; no. 3; pp. 567 - 573
• Main Authors: Del Felice, Alessandra, Magalini, Alessandra, Masiero, Stefano
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2015
• Subjects: Adolescent; Adult; Brain - physiopathology; Cross-Over Studies; Electrical source imaging; Epilepsy rehabilitation; Epilepsy, Temporal Lobe - physiopathology; Epilepsy, Temporal Lobe - psychology; Epilepsy, Temporal Lobe - rehabilitation; Female; Humans; Learning - physiology; Male; Memory - physiology; Memory remediation; Middle Aged; Neurology; Neuropsychological Tests; Non-invasive transcranial stimulation; Sleep - physiology; Sleep spindles; Transcranial Direct Current Stimulation - methods; Young Adult; STAY 1-2; MOCA; MRI; EEG; BDI; TLE; AEDs; Epilepsy rehabilitation; sotDCS; EZ; tDCS; Non-invasive transcranial stimulation; Memory remediation; Electrical source imaging; Sleep spindles; REM; NREM sleep; magnetic resonance imaging; Montreal Cognitive Assessment; State Trait Anxiety 1 and 2; transcranial direct current stimulation; electroencephalography; temporal lobe epilepsy; non-rapid eye movement sleep; epileptogenic zone; anti-epileptic drugs; rapid eye movement sleep; Beck Depression Inventory; slow-oscillatory transcranial direct current stimulation
• ISSN: 1935-861X; 1876-4754; 1876-4754
• DOI: 10.1016/j.brs.2015.01.410

Temporal lobe epilepsy (TLE) is often associated with memory deficits. Given the putative role for sleep spindles memory consolidation, spindle generators skewed toward the affected lobe in TLE subjects may be a neurophysiological marker of defective memory. Slow-oscillatory transcranial direct current stimulation (sotDCS) during slow waves sleep (SWS) has previously been shown to enhance sleep-dependent memory consolidation by increasing slow-wave sleep and modulating sleep spindles. To test if anodal sotDCS over the affected TL prior to a nap affects sleep spindles and whether this improves memory consolidation. Randomized controlled cross-over study. 12 people with TLE underwent sotDCS (0.75 Hz; 0–250 μV, 30 min) or sham before daytime nap. Declarative verbal and visuospatial learning were tested. Fast and slow spindle signals were recorded by 256-channel EEG during sleep. In both study arms, electrical source imaging (ESI) localized cortical generators. Neuropsychological data were analyzed with general linear model statistics or the Kruskal–Wallis test (P or Z < 0.05), and neurophysiological data tested with the Mann–Whitney t test and binomial distribution test (P or Z < 0.05). An improvement in declarative (P = 0.05) and visuospatial memory performance (P = 0.048) emerged after sotDCS. SotDCS increased slow spindle generators current density (Z = 0.001), with a shift to the anterior cortical areas. Anodal sotDCS over the affected temporal lobe improves declarative and visuospatial memory performance by modulating slow sleep spindles cortical source generators. SotDCS appears a promising tool for memory rehabilitation in people with TLE. •sotDCS improves memory consolidation across a nap in people with temporal lobe epilepsy.•SotDCS affects slow sleep spindle cortical generators by increasing current density.•Unilateral fronto-temporal sotDCS improves bilateral temporal lobes functioning.