Advancing Neuroimaging in Nonhuman Primates

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PROJECT SUMMARY The overall objective of this exploratory R21 is to establish proof of principle for developing neuroimaging in conscious monkeys using magnetoencephalography (MEG). We will focus on image acquisition in the MEG environment since the MEG operates silently. This developmental project is a logical extension of our ongoing work, which has proven the feasibility of acquiring MEG in anesthetized monkeys. We recently reported that chronic ethanol (EtOH) self-administration significantly altered signal power of multiple bandwidths across the brain in a vervet monkey model of EtOH abuse (Rowland et al., 2017a). More recent MEG data suggest that Rich Club characteristics of baseline, pre-exposure functional networks predict future drinking phenotypes and power spectral analyses found that resting state brain activity also predicts future drinking. Early exposure to EtOH during a 3-month EtOH induction procedure (Grant et al., 2008) appears to affect predominantly frontal regions and these effects expand to more caudal and subcortical areas with continued drinking. These studies however were conducted under anesthesia, which can complicate interpretation of the results, making it difficult to disentangle the effects of EtOH alone from potential EtOH-anesthesia interactions. We propose to compare brain activity and functional connectivity in fully conscious monkeys to characterize baseline, pre- ethanol brain function and functional networks and then to identify which brain regions are more vulnerable to the early effects of EtOH. Female vervet monkeys will be scanned in the fully conscious state using habituation procedures as outlined in this application. While the monkeys are habituated to conscious imaging, they will be trained to perform a delayed-match-to-sample (DMS) behavioral task as a behavioral measure of EtOH's effects on cognition and motor function. DMS performance measures will be collected throughout the study. Monkeys will be scanned while EtOH naïve, in the task-free state and then during active DMS performance. After baseline MEG acquisition in the pre-EtOH state, the monkeys will begin to drink EtOH using a well- characterized induction procedure during which monkeys drink escalating doses (0.5, 1.0 and 1.5 g/kg) EtOH for 30 days at each dose. MEG will be repeated after completion of each 30 day epoch to determine how dose- and time of exposure (30 days at each dose) affect brain function. The monkeys will be trained to perform a delayed match to sample behavioral task to track how EtOH affects cognitive and motor function as it relates to brain function. During each MEG recording session (EtOH naïve state and after each dose of EtOH), resting state brain function will be recorded followed by acquisition during task performance. The overarching goal of this developmental project is to extend conscious imaging combined with performance on behavioral tasks in our current research program to investigate how and when voluntary alcohol consumption affects functional brain networks in monkeys.