The Effect of 12 Hz Extremely Low-frequency Electromagnetic Field on Visual Memory of Male Macaque Monkeys.

Basic and clinical neuroscience · 2022 · Benefit · Very low evidence

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BenefitVery low evidencePaper 5714

Two male rhesus macaques exposed to a 12-Hz electromagnetic field (0.7 µT) for 4 hours/day for one month showed a significant increase in visual memory after exposure, along with decreased serum cortisol and decreased GR gene expression compared with controls…

Study snapshot

PublicationBasic and clinical neuroscience · 2022

Study typeanimal

Reported directionBenefit

Evidence ratingVery low

Abstract

INTRODUCTION: Today, humans live in a world surrounded by electromagnetic fields. Numerous studies have been conducted to discover the biological, physiological, and behavioral effects of electromagnetic fields on humans and animals. Given the biological similarities between monkeys and humans, The present research aimed to examine Visual Memory (VM), hormonal, genomic, and anatomic changes, in the male rhesus macaques exposed to an Extremely Low-Frequency Magnetic Field (ELF-MF). METHODS: Four male rhesus macaques (Macaca mulatta) were used. For the behavioral tests, the animals should be fasting for 17 hours. For the tests such as visual memory, the animal's cooperation was necessary. Using the radiation protocol, we exposed two monkeys to a 12-Hz electromagnetic field with a magnitude of 0.7 μT (electromagnetic radiation) four hours a day for a month. Before and after the exposure, a visual memory test was conducted using a coated device (visible reward) on a movable stand. Ten milliliters of blood was obtained from the femoral artery of each monkey, and half of it was used to examine cortisol serum levels using the MyBioSource kit (made in the USA). The other half of the blood was used to extract lymphocytes for assaying expressions of Glucocorticoid Receptor (GR) genes before and after radiation using the PCR method. Anatomic studies of the amygdala were carried out based on pre- and post-radiation Magnetic Resonance Imaging (MRI). RESULTS: Research results indicated that visual memory in male primates increased significantly after exposure to the 12-Hz frequency. Hormonal analysis at the 12-Hz frequency showed a decrease in cortisol serum levels. However, visual memory and serum cortisol levels did not change considerably in male primates in the control group. There was no considerable amygdala volumetric difference after exposure to the 12-Hz frequency. The expression of the GR genes decreased in the 12-Hz group compared to the control group. CONCLUSION: In short, these results indicated that ELF might benefit memory enhancement because exposure to the 12-HZ ELF can enhance visual memory. This outcome may be due to a decrease in plasma cortisol and or expression of GR genes. Moreover, direct amygdala involvement in this regard cannot be recommended. HIGHLIGHTS: The effects of Extremely Low-Frequency Electromagnetic Fields (ELF-EMF) of 12 Hz on monkeys were studied.The results showed a reduction in the serum cortisol levels and the expression of GR genes.The amygdala anatomical area changes were not significant in the experimental group.In the experimental group, visual memory (delay of 30- and 60-s evaluation) improved after exposure to a frequency of 12 Hz. PLAIN LANGUAGE SUMMARY: Extremely low-frequency electromagnetic fields are among the most important factors affecting humans. This study aimed to determine the fields of 12-Hz frequency on the visual memory changes of male monkeys. The importance of research is due to the cognitive similarity of monkeys to humans. The findings of the research can be attributed to humans. Behavioral, hormonal, genetic, and anatomical studies indicated improvement in visual memory (test monkeys versus control monkeys). This study demonstrates the effect of the 12-Hz frequency on the monkey's visual memory. Researchers can study 12-Hz frequency in other cognitive indices.

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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 typeanimal

Effect directionbenefit

PopulationMale rhesus macaques (Macaca mulatta)

Sample size4

ExposureELF · 1.2e-05 MHz · 4 hours/day for 1 month

Evidence strengthVery lowConfidence: 74% · Peer reviewed: yes

Main findings

Outcomes measured

Visual memory (visible reward test; 30- and 60-s delay evaluation)
Serum cortisol levels
Glucocorticoid receptor (GR) gene expression in lymphocytes
Amygdala volume (MRI)

Limitations

Very small sample size (n=4; exposure group n=2, control group n=2)
Animal study; generalizability to humans is uncertain
Exposure source/setup details not described beyond frequency and field magnitude
Short exposure duration (1 month)

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 1.2e-05,
    "sar_wkg": null,
    "duration": "4 hours/day for 1 month"
  },
  "population": "Male rhesus macaques (Macaca mulatta)",
  "sample_size": 4,
  "outcomes": [
    "Visual memory (visible reward test; 30- and 60-s delay evaluation)",
    "Serum cortisol levels",
    "Glucocorticoid receptor (GR) gene expression in lymphocytes",
    "Amygdala volume (MRI)"
  ],
  "main_findings": "Two male rhesus macaques exposed to a 12-Hz electromagnetic field (0.7 µT) for 4 hours/day for one month showed a significant increase in visual memory after exposure, along with decreased serum cortisol and decreased GR gene expression compared with controls. No considerable amygdala volumetric difference was observed after exposure.",
  "effect_direction": "benefit",
  "limitations": [
    "Very small sample size (n=4; exposure group n=2, control group n=2)",
    "Animal study; generalizability to humans is uncertain",
    "Exposure source/setup details not described beyond frequency and field magnitude",
    "Short exposure duration (1 month)"
  ],
  "evidence_strength": "very_low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low-frequency",
    "ELF-MF",
    "12 Hz",
    "0.7 µT",
    "rhesus macaque",
    "visual memory",
    "cortisol",
    "glucocorticoid receptor",
    "MRI",
    "amygdala"
  ],
  "suggested_hubs": []
}

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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: 10.32598/bcn.2021.724.8
PubMed: 36589014

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