Journal Article

DZNE-2025-00893

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Memory dependent modulation of hippocampal theta power through frontoparietal phase synchronous brain stimulation.

Ehrhardt, N. M. ; Hanna, J. ; Hayek, D.Extern* ; Fleischmann, R. ; Grittner, U. ; Thielscher, A. ; Flöel, A.DZNE* ; Antonenko, D.

2025
Springer Nature [London]

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Please use a persistent id in citations: doi:10.1038/s41598-025-09841-y

Abstract: Targeting subcortical regions like the hippocampus with non-invasive brain stimulation is challenging due to predominantly cortical distribution of electric fields. Frontoparietal phase-synchronous transcranial alternating stimulation (tACS) offers a promising approach to modulate hippocampal functions, though its ability to induce modulation of oscillatory activity in deep subcortical targets remains to be shown. In this pilot study, we applied dual-site theta-tACS (in-phase between left frontoparietal regions) during a temporal order memory task. To quantify hippocampal activity and connectivity, we performed subcortical source analyses of electroencephalography (EEG) data using a hierarchical subspace pursuit algorithm. While memory did not differ between tACS and sham conditions, we observed tACS-induced increases in hippocampal theta power and its connectivity in individuals with superior memory performance. This study provides first-time evidence that phase-synchronized tACS over lateral frontoparietal areas influences hippocampal theta oscillatory activity, substantiating its potential to modulate hippocampal functions in health and disease.

Keyword(s): Hippocampus: physiology (MeSH) ; Humans (MeSH) ; Male (MeSH) ; Theta Rhythm: physiology (MeSH) ; Female (MeSH) ; Adult (MeSH) ; Parietal Lobe: physiology (MeSH) ; Frontal Lobe: physiology (MeSH) ; Memory: physiology (MeSH) ; Electroencephalography (MeSH) ; Transcranial Direct Current Stimulation: methods (MeSH) ; Young Adult (MeSH) ; Pilot Projects (MeSH)

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Contributing Institute(s):

1. Dementia Prevention – Mechanisms and Clinical Implementation (AG Flöel)

Research Program(s):

1. 353 - Clinical and Health Care Research (POF4-353) (POF4-353)

Appears in the scientific report 2025

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