Effects of THC, CBD, and Their Combination on EEG Dynamics in Rats

Area of Science:

• Neuroscience
• Pharmacology
• Electrophysiology

Background:

• Cannabinoids' effects on brain network activity are not fully understood.
• Electrophysiological changes and their spatial/temporal patterns require further investigation in animal models.

Purpose of the Study:

• To investigate the influence of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on resting-state EEG dynamics.
• To characterize the spatial organization and temporal evolution of cannabinoid-induced electrophysiological effects.

Main Methods:

• Acute oral administration of THC (10 mg/kg), CBD (10 mg/kg), or their combination to freely moving rats.
• Resting-state EEG recording and analysis using spectral decomposition, source localization, and functional connectivity.
• Utilized an anatomically realistic rat head model for source-space analysis.

Main Results:

• Cannabinoid administration increased low-frequency spectral power (delta-beta clusters) in prefrontal, cingulate, hippocampal, and striatal regions.
• THC and THC+CBD treatments produced the most extensive effects; CBD showed fewer and smaller clusters.
• Significant alterations in functional connectivity were observed in CB1 receptor-rich regions, mirroring source-power findings.

Conclusions:

• Cannabinoids induce a specific EEG signature characterized by enhanced low-frequency activity and altered functional connectivity.
• Effects are regionally selective, engaging CB1-rich cortical and limbic structures.
• THC appears to be the primary driver of observed effects, with CBD exerting a weaker, similar modulation.