Study of the development of fetal baboon brain using magnetic resonance imaging at 3 Tesla

Abstract

Direct observational data on the development of the brains of human and nonhuman primates is on remarkably scant, and most of our understanding of primate brain development is extrapolated from findings in rodent models. Magnetic resonance imaging (MRI) is a promising tool for the noninvasive, longitudinal study of the developing primate brain. We devised a protocol to scan pregnant baboons serially at 3 T for up to 3 h per session. Seven baboons were scanned 1-6 times, beginning as early as 56 days post-conceptional age, and as late as 185 days (term ~185 days). Successful scanning of the fetal baboon required careful animal preparation and anesthesia, in addition to optimization of the scanning protocol. We successfully acquired maps of relaxation times (T 1 and T 2 ) and high-resolution anatomical images of the brains of fetal baboons at multiple time points during the course of gestation. These images demonstrated the convergence of gray and white matter contrast near term, and furthermore demonstrated that the loss of contrast at that age is a consequence of the continuous change in relaxation times during fetal brain development. These data furthermore demonstrate that maps of relaxation times have clear advantages over the relaxation time weighted images for the tracking of the changes in brain structure during fetal development. This protocol for in utero MRI of fetal baboon brains will help to advance the use of nonhuman primate models to study fetal brain development longitudinally.

Developments of sulcal pattern and subcortical structures of the forebrain in cynomolgus monkey fetuses: 7-tesla magnetic resonance imaging provides high reproducibility of gross structural changes

“…Recently, developmental profiles of the fetal baboon brain were reported using quantitative T 1 and T 2 maps and diffusion tensor shown in utero (Liu et al 2008). However, the morphological maturation of the forebrain was not fully examined because of insufficient resolution of the in utero MRI at 3-tesla.…”

The average baboon brain: MRI templates and tissue probability maps from 89 individuals

“…The baboon brain also has a larger degree of gyrification (folding) than other Old World monkeys and contains all the primary cortical structures found in humans (Rogers et al, 2010). Accordingly, the baboon model has been used in numerous structural and functional neuroimaging experiments (e.g., Kochunov et al, 2010aKochunov et al, , 2010bKroenke et al, 2005Kroenke et al, , 2007Liu et al, 2008;Miller et al, 2013;Phillips and Kochunov, 2011;Phillips et al, 2012;Rogers et al, 2007;Salinas et al, 2011;Szabo et al, 2007Szabo et al, , 2011aSzabo et al, , 2011bWey et al, 2013).…”

Development of cerebral sulci and gyri in ferrets (Mustela putorius)

“…As is true of humans and non-human primates, they are topologically related to the functional cortical divisions such as the somatosensory Keniston et al 2009) and visual areas Phillip et al 2006). Development of the cerebral sulci and gyri has been well-documented in humans and non-human primates by anatomic study (Turner 1948;Chi et al 1977;Dorovini-Zis and Dolman 1977;Naidich et al 1994;Fukunishi et al 2006;Kashima et al 2008;Sawada et al 2012), sonography (Naidich et al 1986(Naidich et al , 1994Murphy et al 1989;Huang 1991), and by magnetic resonance imaging (MRI) (Martin et al 1988;Naidich et al 1994;van der Knaap et al 1996;Garel et al 2001;Prayer et al 2006;Liu et al 2008;Sawada et al 2009) and studies by three-dimensional (3D) reconstructions of the cortical surface based on MRI (Dubois et al 2008). Developmental changes in the cerebral cortical surface of ferrets have also been reported by neuronatomic studies (Smart and McSherry 1986) and MRI (Neal et al 2007;Barnette et al 2009).…”