Bright light transmits through the brain: Measurement of photon emissions and frequency-dependent modulation of spectral electroencephalographic power

Photons are emitted during brain activity and when applied externally alter its functional connectivity during the resting state. In the present study we applied constant or time varying light (~10,000 lux) stimuli to one side of the skull and measured by photomultiplier tubes the photon density emitted from the opposite side of the skull along its two horizontal planes. Global quantitative electroencephalographic activity (QEEG) was recorded simultaneously. Reliable increases of ~2.5 × 10 W·m during either constant or specific flash frequencies between 3 and 7 Hz as well as enhanced QEEG power in the theta and low beta range were measured. According to source localization by Low Resolution Electromagnetic Tomography (LORETA) the right parahippocampal region was particularly enhanced. Calculations employing known quantitative values for permeability and permittivity of brain tissue were consistent with this frequency band. Estimated concentrations of protons from hydronium ions indicated a Grotthuss chain-like process for moving photon energy through the cerebral medium may have mediated the distance-dependent latency. The results suggest that external light is transmitted through cerebral tissue, can be measured externally, and significantly affects functional connectivity. The findings support the conclusions of Starck et al. (World Journal Neuroscience, 2012).