Research reportFocal 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

- Copper-lined toque diminishes theta and beta-gamma power in right caudal brain.
- sLORETA localized copper-lined toque diminishments to the parahippocampus.
- Hemispheric differences in spectral densities were noted for fixed coronal sections.
- Right parahippocampal gyrus expressed increased theta power relative to left.
- Rostrocaudal differences in hemispheric dominance in fixed human brain.

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 (0.2 μV2 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.