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

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.

Alteration of functional connectivity in the cortex and major brain networks of non-human primates following focused ultrasound exposure in the dorsal striatum

“…This study has several limitations. Firstly, awake and anesthetized NHP may have different patterns of functional connectivity [ 33 ], and isoflurane may affect the results of functional connectivity [ 34 ], although in this study we used a well-established NHP anesthesia protocol [ 35 ] with similar concentration (~1.0%) isoflurane as the other NHP rsfMRI studies. Functional connectivity was also reported to be related with age [ 36 ], and in this study, one NHP involved in the FUS neuromodulation study is much older (~27 years old) than the other NHPs.…”

Longitudinal evaluation of the functional connectivity changes in the secondary somatosensory cortex (S2) of the monkey brain during acute stroke

“…In addition, monkeys are generally scanned under anesthesia. Isoflurane substantially suppresses the neural activation (FC) and increases the CBF in a dose-dependent manner ( Zhang, 2022 ). Also, MRI scans could not be conducted daily in order to increase the power of study due to the concern about the animal care with frequently repeated anesthesia.…”