Dopamine activation modulates oscillatory synchrony in the hippocampal-prefrontal cortex circuitry

Interaction between brain networks forms the functional unit that sustains cognition and behavior. It has been proposed that oscillatory activity can synchronize distant neuronal populations. One crucial aspect to elucidate brain function and its emergent properties is to understand how functional connectivity is modulated in different time scales according to environmental or physiological demand. Modulatory neurotransmitters such as dopamine have been implicated in changes in membrane excitability, modulation of oscillatory power, and coherence in crucial circuits for cognition, such as the hippocampus-prefrontal cortex (HPC-PFC) pathway. However, it is not known how dopaminergic release modulates specifically the phase synchrony of HPC-PFC or which specific dopaminergic receptors are responsible for the effects. In this context, our objective was to investigate the influence of dopaminergic activity on HPC-PFC synchrony and to assess whether the observed effects are receptor-specific. Our results show that dopamine induces HPC-PFC theta synchrony dose-dependently. This effect is not reproduced by apomorphine unspecific agonism or by SKF and quinpirole agonists, which act respectively on D1- and D2-like receptors. Additionally, we observed a late effect with peak activity between 30 and 40 minutes after dopamine 100 nmol, apomorphine 0.75 mg/kg, or quinpirole administration in which the HPC-PFC delta synchrony increased. Together, these results evidence the participation of dopaminergic neurotransmission in regulating HPC-PFC oscillatory dynamics, Influencing the synchronization in slow frequency oscillation and long-distant brain communication.