On the effectiveness of event-related beta tACS on episodic memory formation and motor cortex excitability

Braun, V. , Sokoliuk, R. and Hanslmayr, S. (2017) On the effectiveness of event-related beta tACS on episodic memory formation and motor cortex excitability. Brain Stimulation, 10(5), pp. 910-918. (doi: 10.1016/j.brs.2017.04.129) (PMID:28528736)

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Abstract

Background: Transcranial alternating current stimulation (tACS) is widely used to entrain or modulate brain oscillations in order to investigate causal relationships between oscillations and cognition. Objective: In a series of experiments we here addressed the question of whether event-related, transient tACS in the beta frequency range can be used to entrain beta oscillations in two different domains: episodic memory formation and motor cortex excitability. Methods: In experiments 1 and 2, 72 healthy human participants engaged in an incidental encoding task of verbal and non-verbal material while receiving tACS to the left and right inferior frontal gyrus (IFG) at 6.8 Hz, 10.7 Hz, 18.5 Hz, 30 Hz, 48 Hz and sham stimulation for 2s during stimulus presentation. In experiment 3, tACS was administered for 10s to M1 at the individual motor beta frequency of eight subjects. We investigated the relationship between the size of TMS induced MEPs and tACS phase. Results: Beta tACS did not affect memory performance compared to sham stimulation in experiments 1 and 2. Likewise, in experiment 3, MEP size was not modulated by the tACS phase. Conclusions: Our findings suggest that event-related, transient tACS in the beta frequency range cannot be used to modulate the formation of episodic memories or motor cortex excitability. These null-results question the effectiveness of event-related tACS to entrain beta oscillations and modulate cognition.

Item Type:Articles
Additional Information:This work was supported by grants awarded to S.H. by Deutsche Forschungsgemeinschaft [Emmy Noether Programme Grant HA 5622/1-1]; and the European Research Council [Consolidator Grant Agreement 647954].
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hanslmayr, Professor Simon
Authors: Braun, V., Sokoliuk, R., and Hanslmayr, S.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Brain Stimulation
Publisher:Elsevier
ISSN:1935-861X
ISSN (Online):1876-4754
Published Online:30 April 2017
Copyright Holders:Copyright © 2017 Elsevier Inc.
First Published:First published in Brain Stimulation 10(5): 910-918
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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