Effects of transcranial direct current stimulation over the posterior parietal cortex on episodic memory reconsolidation

Marco Sandrini, Margot Crossman, Rebecca Soerum, Gergely Bartl

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Abstract

Consolidated memories may return to labile/unstable states after their reactivation, thus requiring a restabilization process that is known as reconsolidation. During this time-limited reconsolidation window, reactivated existing memories can be strengthened, weakened or updated with new information.
Previous studies have shown that non-invasive stimulation of the lateral prefrontal cortex after memory reactivation strengthened existing verbal episodic memories through reconsolidation, an effect documented by enhanced delayed memory recall (24h post-reactivation). However, it remains unknown whether the left posterior parietal cortex (PPC), a region involved during reactivation of existing episodic memories, contributes to reconsolidation.
To address this question, in this double-blind experiment healthy participants (n=27) received transcranial direct current stimulation (tDCS) with the anode over the left PPC after reactivation of previously learned verbal episodic memories. Memory recall was tested 24h later. To rule out unspecific effects of memory reactivation or tDCS alone, we included two control groups: one that receives tDCS with the anode over the left PPC without reactivation (n=27) and another one that receives tDCS with the anode over a control site (primary visual cortex) after reactivation (n=27). We hypothesized that tDCS with the anode over the left PPC after memory reactivation would enhance delayed recall through reconsolidation relative to the two control groups.
No significant between groups differences in the mean number of words recalled on day 3 occurred, suggesting no beneficial effect of tDCS over the left PPC.
Alternative explanations were discussed, including efficacy of tDCS, different stimulation parameters, electrode montage, and stimulation site within the PPC.

© 2019, Elsevier. The attached document (embargoed until 28/08/2020) is an author produced version of a paper published in CORTEX uploaded in accordance with the publisher’s self- archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it.

Original languageEnglish
Pages (from-to)78-88
JournalCortex
Volume121
Early online date28 Aug 2019
DOIs
Publication statusPublished - Dec 2019

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