Greater electroencephalographic coherence between left and right temporal lobe structures during increased...

Area of Science:

• Neuroscience
• Geophysics
• Human Physiology

Background:

• Interhemispheric coherence in electroencephalogram (EEG) signals is a key indicator of brain function.
• Global geomagnetic activity has been anecdotally linked to human experiences, but empirical evidence is limited.
• Previous research suggests correlations between geomagnetic activity and neurological phenomena.

Purpose of the Study:

• To investigate the relationship between global geomagnetic activity and interhemispheric EEG coherence.
• To identify specific brain regions and frequency bands affected by geomagnetic fluctuations.
• To explore potential links between geomagnetic activity, brain coherence, and subjective experiences.

Main Methods:

• Collected 19-channel EEG data from 184 healthy adults over three years during rest in a controlled environment.
• Analyzed EEG data for interhemispheric coherence, particularly in caudal temporal regions.
• Utilized source-localization techniques and analyzed residuals to pinpoint neural origins and isolate parahippocampal contributions.
• Correlated EEG coherence measures with concurrent global geomagnetic activity levels (∼8 nT and above).

Main Results:

• Significant increases in interhemispheric coherence were observed in caudal temporal regions at 11 Hz during heightened geomagnetic activity (>∼8 nT).
• Parahippocampal regions showed net differences at 10, 11, and 12 Hz that significantly correlated with geomagnetic activity.
• Further analysis revealed statistically significant peaks in interhemispheric temporal lobe coherence at 7.5 Hz and 19.5 Hz.
• Weak but reliable correlations were found between geomagnetic activity and inter-temporal lobe coherence.

Conclusions:

• Global geomagnetic activity appears to influence interhemispheric temporal lobe coherence in humans during rest.
• The parahippocampal region is a potential neural source affected by these geomagnetic fluctuations.
• Findings align with studies suggesting increased frequency of intrusive experiences (e.g., "presences") during elevated geomagnetic activity (>∼15-20 nT).