P112 Investigations of general cognitive ability on the efficiency of slow oscillatory-tDCS

Abstract

Introduction Application of SO-tDCS during NREM sleep has shown to be beneficial for consolidation of declarative memories, although contradictory reports also exist ( Barham et al., 1974 ). Specifically the disparate results of individual studies led us to investigate task and trait-dependent effects of SO-tDCS on modulating endogenous brain rhythms and its impact on memory consolidation. Objectives The aim of the present study is to determine the interaction between general cognitive abilities and the efficiency of SO-tDCS on manipulating endogenous EEG activity and memory performance. Methods Young healthy students (n = 14, 8 females) participated in three experimental sessions of nocturnal sleep with EEG, EOG and EMG recordings: Stimulation, Sham and one Baseline session without learning. Five different tasks were to be learned prior to sleep and contents recalled the following morning. SO-tDCS (0.8 Hz) was applied during a stimulation period within early NREM sleep. This stimulation consisted five 5-min blocks of SO-tDCS followed each by a 60-s stimulation free interval. IQ performance was tested 7 days after the last sleep session. Results Participants improved on the figural paired-associate task significantly during the stimulation condition as compared to sham (p Summary Our study suggests that externally applied electric fields during NREM sleep can alter endogenous oscillations in the hours following stimulation and this favours the consolidation of a declarative memory. Furthermore, the correlation with IQ performance suggests SO-tDCS efficiency is dependent upon interactions with non-task and or non-state dependent features.