Repeated alcohol drinking in mice is associated with bidirectional alterations in corticostriatal coherence

Decreased functional connectivity between the striatum and frontal cortex is observed in individuals with alcohol use disorder (AUD), and predicts the probability of relapse in abstinent individuals with AUD. To further our understanding of how repeated alcohol consumption impacts the corticostriatal circuit, extracellular electrophysiological recordings (local field potentials; LFPs) were gathered from the nucleus accumbens (NAc) and prefrontal cortex (PFC) of C57BL/6J mice voluntarily consuming alcohol or water using the 2-h access 'drinking-in-the-dark' (DID) procedure. Following a three-day acclimation period wherein only water access was provided during DID, mice were given 14 consecutive days of access to alcohol. Electrophysiology data was collected throughout the entirety of the final day of acclimation (i.e. water baseline) and the first and final days of alcohol access. We evaluated power and coherence at five frequency bands during bouts of drinking. Surprisingly, we only detected significant changes in power in the NAc; no differences were observed in power in the PFC. Increases in NAc power were detected at the Theta, Beta, and Gamma frequencies. At each of these frequencies, increases were identified on the final alcohol session compared to water baseline. Only at the Theta frequency were increases also detected compared to the first alcohol session. Furthermore, significant increases in Delta coherence were observed on the final alcohol session compared to water baseline, whereas significant decreases in Theta and Beta coherence were identified on both alcohol sessions compared to water baseline. These results provide additional support for alterations in the functional coupling of corticostriatal circuits associated with alcohol consumption and suggest the Theta frequency may be uniquely susceptible to these alterations.