Effects of Anesthesia on Cerebral Blood Flow and Functional Connectivity of Nonhuman Primates

SIMPLE SUMMARY: Nonhuman primates (NHPs) mimic most aspects of the human and play a critical role in translational research of neurological diseases. Functional connectivity is frequently examined using resting-state functional MRI (rsfMRI) to assess the functional abnormality in the anesthetized animal brain. As anesthetics show different effects on physiology and neural activity in a dose-dependent manner, specific and safe anesthesia procedures must be considered and applied to keep the animal from stress and motion during rsfMRI scanning. In this review, typical anesthesia protocols and rsfMRI techniques for NHPs are summarized. An optimal anesthesia protocol and rsfMRI scanning protocol for NHPs are introduced. ABSTRACT: Nonhuman primates (NHPs) are the closest living relatives of humans and play a critical and unique role in neuroscience research and pharmaceutical development. General anesthesia is usually required in neuroimaging studies of NHPs to keep the animal from stress and motion. However, the adverse effects of anesthesia on cerebral physiology and neural activity are pronounced and can compromise the data collection and interpretation. Functional connectivity is frequently examined using resting-state functional MRI (rsfMRI) to assess the functional abnormality in the animal brain under anesthesia. The fMRI signal can be dramatically suppressed by most anesthetics in a dose-dependent manner. In addition, rsfMRI studies may be further compromised by inter-subject variations when the sample size is small (as seen in most neuroscience studies of NHPs). Therefore, proper use of anesthesia is strongly demanded to ensure steady and consistent physiology maintained during rsfMRI data collection of each subject. The aim of this review is to summarize typical anesthesia used in rsfMRI scans of NHPs and the effects of anesthetics on cerebral physiology and functional connectivity. Moreover, the protocols with optimal rsfMRI data acquisition and anesthesia procedures for functional connectivity study of macaque monkeys are introduced.