Bioelectromagnetism History, Foundations and Applications (Shoogo Ueno, Tsukasa Shigemitsu)

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Geomagnetic Field Effects on Living Systems

to produce a 20-fold change in lightning activity (Barr et al., 2000). Williams (1992) also reported that El

Nino/La Nina conditions produce corresponding increases and decreases in SR signal intensity, which

may have implications for future global climate change. Rycrof et al. (2000) discuss the topic of the

global atmospheric electric circuit and climate change in greater depth.

Te idea that the fux of GCRs can afect the parameters of SR and the ELF-EMF background can

be tested using the “Forbush efect” (Beloglazov et al., 2006). During solar fares, the fux of GCRs

decreases rapidly (over a day or less) due to modifcation of the near-Earth interplanetary MF. Tis so-

called Forbush decrease is transient and is followed by a gradual recovery over several days (Lockwood,

1971; Cane, 2000). Based on the measurements in the Kola Peninsula of Russia, it was demonstrated

that in all ten events of signifcant Forbush-decreases, the intensity of the ELF-atmospherics decreased

(down to their complete disappearance) (Beloglazov et al., 2006). It was hypothesized that this phenom

enon is caused by a decrease in the intensity of discharges of a special type (sprites and jets) as a result

of a decrease in atmospheric ionization at altitudes of 10–30 km during the Forbush decrease in the fux

of GCRs (Beloglazov et al., 2006).

Regarding the relationship between BP and SR, more participants showed lower BP on enhanced SR

days (Mitsutake et al., 2005). Tat is, 32.1% of the 56 participants showed lower SBP on enhanced SR

days, whereas only 3.6% showed higher SBP on those days (Mitsutake et al., 2005). In contrast, in DBP,

26.8% of the participants showed lower DBP on enhanced SR days, whereas only 3.6% showed higher

DBP on those days (Mitsutake et al., 2005).

In SR frequencies, studies of rats exposed to MFs in the frequency band of 0.01–100 Hz (with magni

tudes of 5, 50, and 5,000 nT) have revealed that MFs at frequencies of 0.02, 0.5–0.6, 5–6, and 8–11 Hz had

the greatest impact on the circulatory system (Ptitsyna et al., 1998). Tere is also an intriguing report of

a BP-lowering efect in humans with mild-to-moderate hypertension afer exposure to 6–8 Hz MFs at

1 μT (Nishimura et al., 2011).

A recent long-term study examined the relationships between the solar and magnetic factors and the

time course and lags of autonomic nervous system responses to changes in solar and geomagnetic activ

ity (Alabdulgader et al., 2018). In this study, the inter-beat-interval (IBI), Total power, low-frequency

(LF) and high-frequency (HF) powers, the LF/HF ratio, and very low-frequency (VLF) power were used

as parameters of HRV measures (Alabdulgader et al., 2018; Table 6.2). Here, the power spectral density

values refect the area under the curve within the specifc bandwidth of the spectrum. Te interac

tions between autonomic neural activity, BP, respiration, and higher-level control centers in the brain

produce both short- and longer-term rhythms in HRV measurements (McCraty and Shafer, 2015).

Te heart rhythm fuctuations are separated into three primary frequency bands: HF, LF, and VLF

(Task Force of the European Society of Cardiology and the North American Society of Pacing and

Electrophysiology, 1996). Te “ultralow-frequency (ULF)” is generally described as geomagnetic activ

ity <3.5 Hz. Te GMF-line resonances are the most common source of ULF wave energy measured on

the ground and exhibit the largest wave amplitudes compared to other oscillations that occur in the

TABLE 6.2 Summary of Magnetic and HRV Frequency Ranges Used in Measurements