fMRI in Non-human Primate: A Review on Factors That Can Affect Interpretation and Dynamic Causal Modeling Application

Abstract

Dynamic causal modeling (DCM)—a framework for inferring hidden neuronal states from brain activity measurements (e. g., fMRI) and their context-dependent modulation—was developed for human neuroimaging, and has not been optimized for non-human primate (NHP) studies, which are usually done under anesthesia. Animal neuroimaging studies offer the potential to improve effective connectivity modeling using DCM through combining functional imaging with invasive procedures such as in vivo optogenetic or electrical stimulation. Employing a Bayesian approach, model parameters are estimated based on prior knowledge of conditions that might be related to neural and BOLD dynamics (e.g., requires empirical knowledge about the range of plausible parameter values). As such, we address the following questions in this review: What factors need to be considered when applying DCM to NHP data? What differences in functional networks, cerebrovascular architecture and physiology exist between human and NHPs that are relevant for DCM application? How do anesthetics affect vascular physiology, BOLD contrast, and neural dynamics—particularly, effective communication within, and between networks? Considering the factors that are relevant for DCM application to NHP neuroimaging, we propose a strategy for modeling effective connectivity under anesthesia using an integrated physiologic-stochastic DCM (IPS-DCM).

Functional maturation in visual pathways predicts attention to the eyes in infant rhesus macaques: Effects of social status

“…MRI scans were completed after the administration of low levels of anesthesia. Decreased amounts of anesthesia relative to other rs-fMRI NHP studies were used to minimize the potential effects of isoflurane and telazol on functional activity and subsequent BOLD signal ( Vincent et al, 2007 , Hutchison et al, 2013 , Li et al, 2013a ), however FC differences with wakeful states may still exist ( Jovellar and Doudet, 2019 ). Of note, these previous studies reported similar changes in BOLD signal between awake versus anesthetized macaques, particularly in signal from the visual system ( Vincent et al, 2007 , Hutchison et al, 2013 , Li et al, 2013a ).…”

Connecting the dots between cell populations, whole-brain activity, and behavior

“…As opto-fMRI is typically carried out in rodents, here we briefly review the history of fMRI with a focus on rats and mice; however, fMRI provides a noninvasive way to measure brain activity in humans, nonhuman primates, rodents, and other species. 8 – 10 With high-field scanners (1.5 T or higher) and variations on technical applications, blood oxygen level-dependent (BOLD) imaging allows for high spatial resolution, whole-brain coverage, and relatively quick scan times. BOLD imaging is the basis of fMRI, and it functions under the assumption that changes in the intensity of the MRI signal depend on changes in the level of blood oxygenation in the brain.…”