Medical/biological study (experimental study)

Higuchi's fractal dimension for analysis of the effect of external periodic stressor on electrical oscillations in the brain med./bio.

By: Hinrikus H, Bachmann M, Karai D, Klonowski W, Lass J, Stepien P, Stepien R, Tuulik V

Published in: Med Biol Eng Comput 2011; 49 (5): 585-591

Aim of study (acc. to author)

To study the application of Higuchi's fractal dimension as a non-linear measure to evaluate the effect of external periodic stressor (microwave exposure) on electrical oscillations in the brain of 14 participants (21-24 years old, seven males, seven females).

Endpoint

effects on the neurological system: brain activity (resting EEG)

Exposure

- low level microwaves
- PW pulsed wave

Exposure	Parameters
Exposure 1: 450 MHz Modulation type: pulsed Exposure duration: 1 min on - 1 min off, for 10 cycles (20 min)	power density: 0.16 mW/cm² spatial average (+/- 0.02 at the left side of the head) power density: 0.025 mW/cm² spatial average (+/- 0.01 at the right side of the head) power density: 0.08 mW/cm² spatial average (+/- 0.01 above the head) power density: 0.8 mW/cm² spatial average (+/- 0.2 at the left side of the neck and the left shoulder) power density: 0.03 mW/cm² spatial average (+/- 0.01 at the right side of the neck and the right shoulder) SAR: 0.303 W/kg peak value (1 g)

Exposure

Parameters

Exposure 1: 450 MHz

Modulation type: pulsed

Exposure duration: 1 min on - 1 min off, for 10 cycles (20 min)

power density: 0.16 mW/cm² spatial average (+/- 0.02 at the left side of the head)
power density: 0.025 mW/cm² spatial average (+/- 0.01 at the right side of the head)
power density: 0.08 mW/cm² spatial average (+/- 0.01 above the head)
power density: 0.8 mW/cm² spatial average (+/- 0.2 at the left side of the neck and the left shoulder)
power density: 0.03 mW/cm² spatial average (+/- 0.01 at the right side of the neck and the right shoulder)
SAR: 0.303 W/kg peak value (1 g)

Exposure 1

Main characteristics

Frequency	450 MHz
Type	electromagnetic field
Exposure duration	1 min on - 1 min off, for 10 cycles (20 min)

Modulation

Modulation type	pulsed
Duty cycle	50 %
Repetition frequency	40 Hz

Exposure setup

Exposure source	13 cm quarter-wave antenna
Setup	antenna placed at a distance of 10 cm from the skin of the left side of the head

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	0.16 mW/cm²	spatial average	estimated	-	+/- 0.02 at the left side of the head
power density	0.025 mW/cm²	spatial average	estimated	-	+/- 0.01 at the right side of the head
power density	0.08 mW/cm²	spatial average	estimated	-	+/- 0.01 above the head
power density	0.8 mW/cm²	spatial average	estimated	-	+/- 0.2 at the left side of the neck and the left shoulder
power density	0.03 mW/cm²	spatial average	estimated	-	+/- 0.01 at the right side of the neck and the right shoulder
SAR	0.303 W/kg	peak value	calculated	1 g	-

Reference articles

Hinrikus H et al. (2008): Effect of low frequency modulated microwave exposure on human EEG: Individual sensitivity
Hinrikus H et al. (2008): Effect of 7, 14 and 21 Hz modulated 450 MHz microwave radiation on human electroencephalographic rhythms
Adair RK (2002): Vibrational resonances in biological systems at microwave frequencies

Exposed system:

human
partial body: left side of the head

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: brain activity (resting EEG; Higuchi's fractal dimension)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

before exposure
during exposure
after exposure

Main outcome of study (acc. to author)

The data of fractal dimension values averaged over a group detected a small (1-2%) but statistically significant increase with exposure in all EEG channels. The fractal dimension was increased for 12 participants, decreased for one, and was constant for one subject. The fractal dimension showed the most remarkable effect in temporal and parietal regions of the left hemisphere where the microwave field was maximal. Changes of fractal dimension in these regions of the right hemisphere were much higher than expected in accordance with the electromagnetic field distribution.
In conclusion, the data showed that the weak periodic electromagnetic field exposure caused an increase of fractal dimension of the recorded EEG signals. The effect was mild but statistically significant in all EEG channels.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

European Union (EU)/European Commission
Nalecz Institute of Biocybernetics and Biomedical Engineering (IBBE), Polish Academy of Sciences (PAS), Warszawa, Poland

Smitha CK et al. (2015): Analysis of fractal dimension of EEG signals under mobile phone radiation
Suhhova A et al. (2009): Effect of modulated microwave radiation on human EEG asymmetry
Hinrikus H et al. (2009): Effect of modulated at different low frequencies microwave radiation on human EEG
Marino AA et al. (2009): The Effects of Mobile-Phone Electromagnetic Fields on Brain Electrical Activity: A Critical Analysis of the Literature
van Rongen E et al. (2009): Effects of radiofrequency electromagnetic fields on the human nervous system
Hinrikus H et al. (2008): Effect of 7, 14 and 21 Hz modulated 450 MHz microwave radiation on human electroencephalographic rhythms
Hinrikus H et al. (2008): Effect of low frequency modulated microwave exposure on human EEG: Individual sensitivity
Suhhova A et al. (2008): Effect of Microwave Radiation on EEG Coherence
Valentini E et al. (2007): Neurophysiological effects of mobile phone electromagnetic fields on humans: a comprehensive review
Bachmann M et al. (2007): Individual changes in human EEG caused by 450 MHz microwave modulated at 40 and 70 Hz
Bachmann M et al. (2005): Non-linear analysis of the electroencephalogram for detecting effects of low-level electromagnetic fields
Sienkiewicz Z et al. (2005): Neurobehavioural effects of electromagnetic fields
Bachmann M et al. (2005): Effect of 450 MHz Microwave Modulated with 217 Hz on Human EEG in Rest
Hinrikus H et al. (2005): Non-Thermal Effect of Microwave Radiation on Human Brain
Hinrikus H et al. (2004): Changes in human EEG caused by low level modulated microwave stimulation

Higuchi's fractal dimension for analysis of the effect of external periodic stressor on electrical oscillations in the brain med./bio.

Aim of study (acc. to author)

Endpoint

Exposure

Exposure 1

Main characteristics

Modulation

Exposure setup

Parameters

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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