Neuroscience Letters 516 (2012) 54– 56
Volume 516, Issue 1, 10 May 2012, Pages 54–56
Neurosci Lett. 2012 May 10;516(1):54-6. Epub 2012 Mar 28.
Experimental simulation of the effects of sudden increases in geomagnetic
activity upon quantitative measures of human brain activity: Validation of correlational studies
Bryce P. Mulligan a,1 , Michael A. Persinger a,b,c,∗
a Behavioural Neuroscience Laboratory, Sudbury, Ontario, Canada P3E 2C6
b Department of Biology, Sudbury, Ontario, Canada P3E 2C6
c Biomolecular Sciences Program, Sudbury, Ontario, Canada P3E 2C6
Received 2 December 2011
Received in revised form 16 March 2012
Accepted 19 March 2012
- Received 2 December 2011. Revised 16 March 2012. Accepted 19 March 2012. Available online 28 March 2012.
Geomagnetic activity simulation
ELF magnetic ﬁelds
Previous correlations between geomagnetic activity and quantitative changes in electroencephalographic power revealed particular associations with the right parietal lobe for theta activity and the right frontal region for gamma activity. In the present experiment subjects were exposed to either no field (sham conditions) or to either 20 nT or 70 nT, 7 Hz, amplitude modulated (mHz range) magnetic fields for 30 min. Quantitative electroencephalographic (QEEG) measurements were completed before, during, and after the field exposures. After about 10 min of exposure theta power over the right parietal region was enhanced for the 20 nT exposure but suppressed for the 70 nT exposure relative to sham field exposures. The effect dissipated by the end of the exposure. These results support the contention that magnetic field fluctuations were primarily responsible for the significant geomagnetic–QEEG correlations reported in several studies.
► Simulates theta power changes shown by geomagnetic correlations. ► Experimental effect occurs over same brain region. ► Cerebral power shifts require 10 min thus minimizing artifact. ► Major effect in 20 nT range rather than higher intensity. ► Pattern of field designed to imitate a sudden magnetic commencement.