Quantitative Investigation of Connections of the Prefrontal Cortex in the Human and Macaque using Probabilistic Diffusion Tractography

Abstract

The functions of prefrontal cortex (PFC) areas are constrained by their anatomical connections. There is little quantitative information about human PFC connections, and, instead, our knowledge of primate PFC connections is derived from tracing studies in macaques. The connections of subcortical areas, in which white matter penetration and hence diffusion anisotropy are greatest, can be studied with diffusion-weighted imaging (DWI) tractography. We therefore used DWI tractography in four macaque and 10 human hemispheres to compare the connections of PFC regions with nine subcortical regions, including several fascicles and several subcortical nuclei. A distinct connection pattern was identified for each PFC and each subcortical region. Because some of the fascicles contained connections with posterior cortical areas, it was also possible to draw inferences about PFC connection patterns with posterior cortical areas. Notably, it was possible to identify similar circuits centered on comparable PFC regions in both species; PFC regions probably engage in similar patterns of regionally specific functional interaction with other brain areas in both species. In the case of one area traditionally assigned to the human PFC, the pars opercularis, the distribution of connections was not reminiscent of any macaque PFC region but, instead, resembled the pattern for macaque ventral premotor area. Some limitations to the DWI approach were apparent; the high diffusion anisotropy in the corpus callosum made it difficult to compare connection probability values in the adjacent cingulate region.

Fiber connectivity between the striatum and cortical and subcortical regions is associated with temperaments in Chinese males

“…S2 and S3) was consistent with the segmentation pattern reported in previous studies (Cohen et al, 2009;Croxson et al, 2005;Lehericy et al, 2004;Voorn et al, 2004), which confirmed the probabilistic tracking process of diffusion tensor images in the present study.…”

“…Images in the MNI standard space were entered into general linear models (GLMs) for voxel-wise analyses. The method has been well validated and used in diffusion tensor imaging studies (Cohen et al, 2009;Croxson et al, 2005;Johansen-Berg and Rushworth, 2009). …”

Defining functional areas in individual human brains using resting functional connectivity MRI

“…Recently, the use of areal connections to define areas has been employed in humans. Diffusion tensor imaging (DTI) tractography, which measures the directional diffusion of water within a voxel, can reveal local anisotropic differences in fiber bundles in neighboring regions of cortex in living humans, and was recently used to delineate some human cortical areas Croxson et al, 2005;Johansen-Berg et al, 2004;Johansen-Berg et al, 2005;Klein et al, 2007). The use of probabilistic fiber bundle differences in diffusion tractography is in some respects analogous to the use of blunt dissection to identify major fiber bundles in humans.…”

Frontal lobe hypoactivation in medication-free adults with bipolar II depression during response inhibition

“…The prefrontal cortex (PFC), which includes the dorsolateral prefrontal cortex (DLPFC), orbital frontal cortex (OFC) and the inferior frontal cortex (IFC), plays a central role in executive functioning through its influence on subcortical and posterior cortical regions via extensive anatomical connections to these areas (Croxson et al, 2005;Leh et al, 2007). Recent evidence suggests that successful response inhibition is mediated through striatal dopamine receptors in this frontal-striatal circuit (Ghahremani et al, 2012), and that increased activation of this network is associated with improvement in response-inhibition performance (Congdon et al, 2010).…”