Weak ELF magnetic field effects on hippocampal rhythmic slow activity

Area of Science:

• Neuroscience
• Biophysics
• Electromagnetic Fields

Background:

• Central nervous system (CNS) electrical activity is influenced by extremely-low-frequency (ELF) magnetic fields.
• CNS structures with endogenous oscillation and synchrony are susceptible to field coupling.
• The rat hippocampus exhibits rhythmic slow activity (RSA), a synchronized neuronal oscillation.

Purpose of the Study:

• To investigate the effect of a 16.0 Hz, 28.9 microT(rms) sinusoidal magnetic field on RSA in the rat hippocampus.
• To determine if ELF magnetic field exposure alters the stability of hippocampal neuronal oscillations.

Main Methods:

• Used an in vivo rat model under urethane anesthesia.
• Applied an externally applied sinusoidal magnetic field (16.0 Hz; 28.9 microT(rms)) for 60 minutes.
• Monitored changes in hippocampal field potential oscillations, specifically RSA and large irregular-amplitude activity (LIA).

Main Results:

• Exposure to the ELF magnetic field significantly increased the probability of RSA decaying to LIA.
• This induced instability in neural oscillations persisted for up to 90 minutes postexposure.
• The findings suggest that endogenous CNS oscillators are sensitive to field-mediated perturbation.

Conclusions:

• Endogenous neural oscillators, like those in the hippocampus, are susceptible to ELF magnetic field exposure.
• The sensitivity of these networks to ELF fields may be greater than previously assumed.
• Network nonlinearities might amplify endogenous fields, affecting neuronal synchrony.