Transduction of the Geomagnetic Field as Evidenced from Alpha-band Activity in the Human Brain

2019 · Mixed · Insufficient evidence

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MixedInsufficient evidencePaper 1875

Study snapshot

Publicationmanual · 2019

Study typeother

Reported directionMixed

Evidence ratingInsufficient

Abstract

Transduction of the Geomagnetic Field as Evidenced from Alpha-band Activity in the Human Brain Wang CX, Hilburn IA, Wu D-A, Mizuhara Y, Cousté CP, Abrahams JNH, Bernstein SE, Matani A, Shimojo S. Kirschvink JL. Transduction of the Geomagnetic Field as Evidenced from Alpha-band Activity in the Human Brain. eNeuro 18 March 2019, ENEURO.0483-18.2019; DOI: doi.org Abstract Magnetoreception, the perception of the geomagnetic field, is a sensory modality well-established across all major groups of vertebrates and some invertebrates, but its presence in humans has been tested rarely, yielding inconclusive results. We report here a strong, specific human brain response to ecologically-relevant rotations of Earth-strength magnetic fields. Following geomagnetic stimulation, a drop in amplitude of EEG alpha oscillations (8-13 Hz) occurred in a repeatable manner. Termed alpha event-related desynchronization (alpha-ERD), such a response has been associated previously with sensory and cognitive processing of external stimuli including vision, auditory and somatosensory cues. Alpha-ERD in response to the geomagnetic field was triggered only by horizontal rotations when the static vertical magnetic field was directed downwards, as it is in the Northern Hemisphere; no brain responses were elicited by the same horizontal rotations when the static vertical component was directed upwards. This implicates a biological response tuned to the ecology of the local human population, rather than a generic physical effect. Biophysical tests showed that the neural response was sensitive to static components of the magnetic field. This rules out all forms of electrical induction (including artifacts from the electrodes) which are determined solely on dynamic components of the field. The neural response was also sensitive to the polarity of the magnetic field. This rules out free-radical 'quantum compass' mechanisms like the cryptochrome hypothesis, which can detect only axial alignment. Ferromagnetism remains a viable biophysical mechanism for sensory transduction and provides a basis to start the behavioral exploration of human magnetoreception. Significance Statement Although many migrating and homing animals are sensitive to Earth's magnetic field, most humans are not consciously aware of the geomagnetic stimuli that we encounter in everyday life. Either we have lost a shared, ancestral magnetosensory system, or the system lacks a conscious component with detectable neural activity but no apparent perceptual awareness by us. We found two classes of ecologically-relevant rotations of Earth- strength magnetic fields that produce strong, specific and repeatable effects on human brainwave activity in the EEG alpha band (8-13 Hz); EEG discriminates in response to different geomagnetic field stimuli. Biophysical tests rule out all except the presence of a ferromagnetic transduction element, such as biologically-precipitated crystals of magnetite (Fe3O4). Conclusion Our results indicate that at least some modern humans transduce changes in Earth-strength magnetic fields into an active neural response. We hope that this study provides a road-map for future studies aiming to replicate and extend research into human magnetoreception. Given the known presence of highly-evolved geomagnetic navigation systems in species across the animal kingdom, it is perhaps not surprising that we might retain at least some functioning neural components especially given the nomadic hunter/gatherer lifestyle of our not- too-distant ancestors. The full extent of this inheritance remains to be discovered. Open access paper: eneuro.org

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeother

Effect directionmixed

Populationhumans

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 66% · Peer reviewed: yes

Main findings

Ecologically-relevant rotations of Earth-strength magnetic fields elicited a repeatable drop in EEG alpha oscillation amplitude (alpha-ERD). Responses occurred only for horizontal rotations when the static vertical magnetic field component was directed downwards; the same rotations with the vertical component directed upwards elicited no brain responses. Biophysical tests indicated sensitivity to static field components and polarity.

Outcomes measured

EEG alpha-band activity (8–13 Hz)
alpha event-related desynchronization (alpha-ERD) amplitude changes in response to magnetic field rotations

Limitations

Sample size not reported in provided abstract/metadata
Exposure parameters (exact field strengths, rotation rates, timing) not fully specified in provided abstract/metadata
Behavioral/perceptual outcomes not reported; findings are neural (EEG) responses only

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "geomagnetic field rotations (Earth-strength magnetic fields)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "humans",
  "sample_size": null,
  "outcomes": [
    "EEG alpha-band activity (8–13 Hz)",
    "alpha event-related desynchronization (alpha-ERD) amplitude changes in response to magnetic field rotations"
  ],
  "main_findings": "Ecologically-relevant rotations of Earth-strength magnetic fields elicited a repeatable drop in EEG alpha oscillation amplitude (alpha-ERD). Responses occurred only for horizontal rotations when the static vertical magnetic field component was directed downwards; the same rotations with the vertical component directed upwards elicited no brain responses. Biophysical tests indicated sensitivity to static field components and polarity.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in provided abstract/metadata",
    "Exposure parameters (exact field strengths, rotation rates, timing) not fully specified in provided abstract/metadata",
    "Behavioral/perceptual outcomes not reported; findings are neural (EEG) responses only"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.66,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "magnetoreception",
    "geomagnetic field",
    "Earth-strength magnetic fields",
    "EEG",
    "alpha band",
    "alpha-ERD",
    "magnetic field polarity",
    "static magnetic field",
    "human brain response"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.2,
      "reason": "Involves human exposure to magnetic fields, but not RF/ELF guideline-focused content in the provided abstract."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1523/eneuro.0483-18.2019
PubMed: Not supplied

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