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Effects of TDCS dosage on working memory in healthy participants.
Brain Stimul 2018 May - Jun; 11(3):518-527BS

Abstract

BACKGROUND

Transcranial direct current stimulation (tDCS) has been found to improve working memory (WM) performance in healthy participants following a single session. However, results are mixed and the overall effect size is small. Interpretation of these results is confounded by heterogeneous study designs, including differences in tDCS dose (current intensity) and sham conditions used.

AIMS

We systematically investigated the effect of tDCS dose on working memory using behavioural and neurophysiological outcomes.

METHODS

In a single-blind parallel group design, 100 participants were randomised across five groups to receive 15 min of bifrontal tDCS at different current intensities (2 mA, 1 mA, and three sham tDCS conditions at 0.034 mA, 0.016 mA, or 0 mA). EEG activity was acquired while participants performed a WM task prior to, during, and following tDCS. Response time, accuracy and an event-related EEG component (P3) were evaluated.

RESULTS

We found no significant differences in response time or performance accuracy between current intensities. The P3 amplitude was significantly lower in the 0 mA condition compared to the 0.034 mA, 1 mA and 2 mA tDCS conditions. Changes in WM accuracy were moderately correlated with changes in frontal P3 amplitude (channel Fz) following tDCS compared to baseline levels (r = 0.34).

CONCLUSIONS

Working memory was not significantly altered by tDCS, regardless of dose. The P3 amplitude showed that stimulation at 1 mA, 2 mA and a sham condition (0.034 mA) had biological effects, with the largest effect size for 1 mA stimulation. These findings indicate higher sensitivity of neurophysiological outcomes to tDCS and suggests that sham stimulation previously considered inactive may alter neuronal function.

Authors+Show Affiliations

School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia. Electronic address: stevan.nikolin@unsw.edu.au.School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia.School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia; St. George Hospital, Sydney, Australia.School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia; Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, Brisbane, Australia.

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29361442

Citation

Nikolin, Stevan, et al. "Effects of TDCS Dosage On Working Memory in Healthy Participants." Brain Stimulation, vol. 11, no. 3, 2018, pp. 518-527.
Nikolin S, Martin D, Loo CK, et al. Effects of TDCS dosage on working memory in healthy participants. Brain Stimul. 2018;11(3):518-527.
Nikolin, S., Martin, D., Loo, C. K., & Boonstra, T. W. (2018). Effects of TDCS dosage on working memory in healthy participants. Brain Stimulation, 11(3), pp. 518-527. doi:10.1016/j.brs.2018.01.003.
Nikolin S, et al. Effects of TDCS Dosage On Working Memory in Healthy Participants. Brain Stimul. 2018;11(3):518-527. PubMed PMID: 29361442.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of TDCS dosage on working memory in healthy participants. AU - Nikolin,Stevan, AU - Martin,Donel, AU - Loo,Colleen K, AU - Boonstra,Tjeerd W, Y1 - 2018/01/08/ PY - 2017/09/25/received PY - 2017/12/01/revised PY - 2018/01/04/accepted PY - 2018/1/24/pubmed PY - 2019/2/9/medline PY - 2018/1/24/entrez KW - EEG KW - Working memory KW - tDCS SP - 518 EP - 527 JF - Brain stimulation JO - Brain Stimul VL - 11 IS - 3 N2 - BACKGROUND: Transcranial direct current stimulation (tDCS) has been found to improve working memory (WM) performance in healthy participants following a single session. However, results are mixed and the overall effect size is small. Interpretation of these results is confounded by heterogeneous study designs, including differences in tDCS dose (current intensity) and sham conditions used. AIMS: We systematically investigated the effect of tDCS dose on working memory using behavioural and neurophysiological outcomes. METHODS: In a single-blind parallel group design, 100 participants were randomised across five groups to receive 15 min of bifrontal tDCS at different current intensities (2 mA, 1 mA, and three sham tDCS conditions at 0.034 mA, 0.016 mA, or 0 mA). EEG activity was acquired while participants performed a WM task prior to, during, and following tDCS. Response time, accuracy and an event-related EEG component (P3) were evaluated. RESULTS: We found no significant differences in response time or performance accuracy between current intensities. The P3 amplitude was significantly lower in the 0 mA condition compared to the 0.034 mA, 1 mA and 2 mA tDCS conditions. Changes in WM accuracy were moderately correlated with changes in frontal P3 amplitude (channel Fz) following tDCS compared to baseline levels (r = 0.34). CONCLUSIONS: Working memory was not significantly altered by tDCS, regardless of dose. The P3 amplitude showed that stimulation at 1 mA, 2 mA and a sham condition (0.034 mA) had biological effects, with the largest effect size for 1 mA stimulation. These findings indicate higher sensitivity of neurophysiological outcomes to tDCS and suggests that sham stimulation previously considered inactive may alter neuronal function. SN - 1876-4754 UR - https://www.unboundmedicine.com/medline/citation/29361442/Effects_of_TDCS_dosage_on_working_memory_in_healthy_participants_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1935-861X(18)30031-7 DB - PRIME DP - Unbound Medicine ER -