Modulation of Working Memory by an Alternating Magnetic Field in Humans

Overview

Many studies have examined the effects of transcranial alternating current stimulation (tACS) on working memory, showing that low-intensity stimulation can enhance cognitive performance by modulating neuronal activity, particularly in the frontal cortex and the parietal lobule. Specific frequencies, such as the gamma frequency, have demonstrated beneficial effects on memory under high cognitive load. However, tACS has technical limitations, including uncomfortable sensations and uneven diffusion of electrical currents within the brain, which restrict its effectiveness in deeper brain regions. Transcranial alternating magnetic stimulation (tAMS) is emerging as a potentially more precise and comfortable method. Unlike tACS, tAMS uses magnetic fields that penetrate more deeply into the brain and provide a more homogeneous distribution of induced electrical currents, allowing for more targeted stimulation. This study compares the effects of tACS and tAMS on working memory, with the hypothesis that tAMS will offer additional advantages in terms of comfort and efficacy. Cognitive performance will be assessed using working memory tasks, along with EEG signals to analyze neuronal modulations. The objective is to demonstrate that tAMS more effectively reaches deep brain regions and improves cognitive functions.

Interventions

• Other Electrical stimulation
  The experimental session lasts 2 hours and 30 minutes and includes four phases: Time 0, dedicated to training and adjustment of task difficulty, followed by Time 1, Time 2, and Time 3, corresponding respectively to assessments of working memory performance before, during, and after exposure to stimulation. Each phase includes blocks of the Sternberg task, for a total of 180 trials per session. Each block lasts 10 minutes.
• Other Magnetic stimulation
  The experimental session lasts 2 hours and 30 minutes and includes four time points: Time 0, dedicated to training and adjustment of task difficulty, followed by Time 1, Time 2, and Time 3, corresponding respectively to assessments of working memory performance before, during, and after exposure to stimulation. Each time point includes blocks of the Sternberg task, for a total of 180 trials per session. Each block lasts 10 minutes.
• Other No stimulation
  The experimental session lasts 2 hours and 30 minutes and includes four time points: Time 0, dedicated to training and adjustment of task difficulty, followed by Time 1, Time 2, and Time 3, corresponding respectively to assessments of working memory performance before, during, and after exposure to sham stimulation. Each time point includes blocks of the Sternberg task, for a total of 180 trials per session. Each block lasts 10 minutes.

Primary outcome measures

• Sternberg task [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]

Secondary outcome measures (9)

• EEG Power Outcomes [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• EEG Power Outcomes [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• EEG Power Outcomes [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• EEG Power Outcomes [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• EEG Power Outcomes [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• EEG Signal Regularity Outcomes (RQA) [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• EEG Signal Regularity Outcomes (RQA) [Time frame: Baseline (Day 1, before exposure), periprocedural (Day 1, during exposure), and post-intervention (Day 1, immediately after exposure)]
• Neuropsychological data [Time frame: Baseline (Day 1, before exposure)]
• Neuropsychological data [Time frame: Baseline (Day 1, before exposure)]

Eligibility criteria

Inclusion criteria

• Written, voluntary, and informed consent to participate in the study
• Fluent French speaker (task instructions are provided in French)
• Normal or corrected-to-normal vision using contact lenses only

Non inclusion Criteria:

• Individuals deprived of liberty by law
• Individuals under legal guardianship or curatorship
• Pregnant or breastfeeding women
• Presence of metallic implants in the head, implanted electronic devices, or any other metallic object that cannot be removed for the experiment (e.g. dental fillings)
• History of neurological or psychiatric disorders according to the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition)
• History of pathology or chronic disease affecting memory or attention
• Drug or alcohol consumption within the previous 24 hours

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Basic science

Study locations

Center list to be confirmed — check the primary protocol.

Identifiers

NCT: NCT07398833 · 2025-A00296-43

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗