Influence of an alternating 3 Hz magnetic field with an induction of 0.1 millitesla on chosen parameters of the human occipital EEG.

Abstract

In 62 volunteers it was studied, whether an alternating 3 Hz magnetic field (induction 0.1 mT) vertically applied to the head over a period of 20 min causes changes in EEG parameters. The study's design was a random crossover controlled, blind one. The field was generated by a Helmholtz coils arrangement. The occipital surface EEGs (O1 and O2) were derived against the left earlobe. Significant differences (two-tailed P < 0.05) between sham and real exposure were found for the relative spectral amplitudes of the theta (3.5-7.5 Hz) and beta band (12.5-25.0 Hz) and the theta/beta ratio. These observations can be interpreted as a more pronounced reduction of alertness under the real field condition compared with the control.

AI evidence extraction

Main findings

In a randomized, blind, crossover, sham-controlled study of 62 volunteers, a vertically applied alternating 3 Hz magnetic field (0.1 mT) for 20 minutes produced statistically significant differences versus sham in occipital EEG relative spectral amplitudes in the theta and beta bands and in the theta/beta ratio (two-tailed P < 0.05). The authors interpret these EEG changes as indicating a more pronounced reduction of alertness during real-field exposure compared with control.

Outcomes measured

• Occipital EEG spectral parameters (relative spectral amplitudes)
• Theta band (3.5–7.5 Hz) relative spectral amplitude
• Beta band (12.5–25.0 Hz) relative spectral amplitude
• Theta/beta ratio
• Alertness (interpretation based on EEG changes)

Limitations

• Only occipital surface EEG (O1, O2) reported; other brain regions not described
• Short exposure duration (20 min)
• Details on randomization procedure, blinding assessment, and effect sizes are not provided in the abstract
• Alertness outcome is inferred from EEG parameters rather than directly measured (per abstract interpretation)

Suggested hubs

• occupational-exposure (0.2)
  ELF magnetic-field exposure study; however exposure appears experimental rather than workplace-based.

{
    "study_type": "randomized_trial",
    "exposure": {
        "band": "ELF",
        "source": "experimental (Helmholtz coils; head exposure)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "20 min"
    },
    "population": "62 volunteers",
    "sample_size": 62,
    "outcomes": [
        "Occipital EEG spectral parameters (relative spectral amplitudes)",
        "Theta band (3.5–7.5 Hz) relative spectral amplitude",
        "Beta band (12.5–25.0 Hz) relative spectral amplitude",
        "Theta/beta ratio",
        "Alertness (interpretation based on EEG changes)"
    ],
    "main_findings": "In a randomized, blind, crossover, sham-controlled study of 62 volunteers, a vertically applied alternating 3 Hz magnetic field (0.1 mT) for 20 minutes produced statistically significant differences versus sham in occipital EEG relative spectral amplitudes in the theta and beta bands and in the theta/beta ratio (two-tailed P < 0.05). The authors interpret these EEG changes as indicating a more pronounced reduction of alertness during real-field exposure compared with control.",
    "effect_direction": "harm",
    "limitations": [
        "Only occipital surface EEG (O1, O2) reported; other brain regions not described",
        "Short exposure duration (20 min)",
        "Details on randomization procedure, blinding assessment, and effect sizes are not provided in the abstract",
        "Alertness outcome is inferred from EEG parameters rather than directly measured (per abstract interpretation)"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF magnetic field",
        "3 Hz",
        "0.1 mT",
        "Helmholtz coils",
        "randomized crossover",
        "sham-controlled",
        "blind",
        "EEG",
        "occipital",
        "theta",
        "beta",
        "theta/beta ratio",
        "alertness"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.200000000000000011102230246251565404236316680908203125,
            "reason": "ELF magnetic-field exposure study; however exposure appears experimental rather than workplace-based."
        }
    ]
}

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