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Brain Res. 2016 Aug 1;1644:267-77. doi: 10.1016/j.brainres.2016.05.034. Epub 2016 May 19.

Focal attenuation of specific electroencephalographic power over the right parahippocampal region during transcerebral copper screening in living subjects and hemispheric asymmetric voltages in fixed brain tissue.

Author information

1
Biomolecular Sciences & Behavioural Neuroscience Programs, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6.
2
Department of Biology & Behavioural Neuroscience Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6.
3
Biomolecular Sciences & Behavioural Neuroscience Programs, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6. Electronic address: mpersinger@laurentian.ca.

Abstract

Covering the heads of human volunteers with a toque lined with copper mesh compared to no mesh resulted in significant diminishments in quantitative electroencephalographic power within theta and beta-gamma bands over the right caudal hemisphere. The effect was most evident in women compared to men. The significant attenuation of power was verified by LORETA (low resolution electromagnetic tomography) within the parahippocampal region of the right hemisphere. Direct measurements of frequency-dependent voltages of coronal section preserved in ethanol-formalin-acetic acid from our human brain collection revealed consistently elevated power (0.2μV(2)Hz(-1)) in right hemispheric structures compared to left. The discrepancy was most pronounced in the grey (cortical) matter of the right parahippocampal region. Probing the superficial convexities of the cerebrum in an unsectioned human brain demonstrated rostrocaudal differences in hemispheric spectral power density asymmetries, particularly over caudal and parahippocampal regions, which were altered as a function of the chemical and spatial contexts imposed upon the tissue. These results indicate that the heterogeneous response of the human cerebrum to covering of the head by a thin conductor could reflect an intrinsic structure and unique electrical property of the (entorhinal) cortices of the right caudal hemisphere that persists in fixed tissue.

KEYWORDS:

Entorhinal cortices; Human brain; LORETA; Parahippocampal gyrus; QEEG; Theta activity

PMID:
27211475
DOI:
10.1016/j.brainres.2016.05.034
[Indexed for MEDLINE]

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