Dysfunctional prefrontal cortical network activity and interactions following cannabinoid receptor activation

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Coordinated neural activity across distributed brain networks is crucial for cognitive functions.
• Limbic-cortical interactions, particularly involving the hippocampus and medial prefrontal cortex (mPFC), are vital for learning, memory, and decision-making.
• Cannabinoid receptors modulate neural activity, and their activation can disrupt coordinated brain function.

Purpose of the Study:

• To investigate the role of network oscillations in hippocampal-mPFC interactions during cognitive tasks.
• To examine how CP55940, a cannabinoid receptor agonist, affects neural activity and coordination in these regions.
• To understand the link between disrupted network activity and cognitive deficits induced by cannabinoid receptor activation.

Main Methods:

• Utilized rats as the experimental model.
• Administered CP55940, a potent cannabinoid receptor agonist.
• Recorded local field potentials (LFPs) and single-unit activity in the hippocampus (CA1) and mPFC.
• Analyzed power spectrum and coherence of network oscillations (e.g., theta and gamma bands).
• Assessed performance in a spatial working memory task.

Main Results:

• CP55940 dose-dependently reduced low-frequency power in the hippocampus and high-frequency power in the mPFC.
• Cannabinoid receptor activation impaired theta and gamma oscillations during a decision-making task.
• Disrupted theta-frequency coherence between the hippocampus and mPFC was observed.
• Cognitive deficits correlated with impaired neural coordination and reduced task accuracy.
• Impaired phase-locking of mPFC neuronal firing to hippocampal theta and local gamma rhythms.

Conclusions:

• Hippocampal (CA1) and mPFC network oscillations are critical for cognitive processes.
• Disrupted theta-frequency coordination between the hippocampus and mPFC contributes to cognitive impairments caused by cannabinoid receptor activation.
• Exogenous cannabinoid receptor activation disrupts limbic-cortical communication essential for cognition.