No Effect of Anodal tDCS on Verbal Episodic Memory Performance and Neurotransmitter Levels in Young and Elderly Participants

Figure 1

Experimental setup. (a) Study procedure during three experimental sessions. Baseline: assessments of initial cognitive task performance. MR sessions: verbal episodic memory task while receiving either sham or real anodal tDCS during encoding phase inside the MR scanner. MR spectra were acquired immediately before and after the encoding phase. Delayed retrieval outside MR scanner. Each participant received both sham and real anodal tDCS in a randomized sequence. (b) Verbal episodic memory task. The encoding phase consisted of presentation and immediate retrieval of forty nouns in three successive rounds. During the retrieval phase, participants performed a delayed free recall and a recognition task. Following the MR sessions, a second delayed recall was performed on the day after the session. (c) Electrode arrangement for application of anodal tDCS to the left DLPFC with the cathode placed supraorbitally on the contralateral side. (d) Example for voxel ( cm) position in the left DLPFC. (e) Example of a 3T MR difference spectrum, including model fit and residuals.

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