The visual white matter: The application of diffusion MRI and fiber tractography to vision science.

Ariel Rokem,Marlene Behrmann,Hiromasa Takemura,Franco Pestilli,K Suzanne Scherf,Brian A Wandell,Holly Bridge,Ione Fine,Andrew S Bock

doi:10.1167/17.2.4

Abstract

Visual neuroscience has traditionally focused much of its attention on understanding the response properties of single neurons or neuronal ensembles. The visual white matter and the long-range neuronal connections it supports are fundamental in establishing such neuronal response properties and visual function. This review article provides an introduction to measurements and methods to study the human visual white matter using diffusion MRI. These methods allow us to measure the microstructural and macrostructural properties of the white matter in living human individuals; they allow us to trace long-range connections between neurons in different parts of the visual system and to measure the biophysical properties of these connections. We also review a range of findings from recent studies on connections between different visual field maps, the effects of visual impairment on the white matter, and the properties underlying networks that process visual information supporting visual face recognition. Finally, we discuss a few promising directions for future studies. These include new methods for analysis of MRI data, open datasets that are becoming available to study brain connectivity and white matter properties, and open source software for the analysis of these data.

Highlights

The cerebral hemispheres of the human brain can be subdivided into two primary tissue types: the white matter and the gray matter (Fields, 2008a)
Given that there were age-related declines in the micro- and macrostructural properties of the inferior fronto-occipital fasciculus (IFOF) as well as in face perception behavior, we explored whether there was an association between these tract and behavioral deficits
Given the findings of an association between face processing behavior and the structural properties of the IFOF in typically developing adults, we investigated whether congenital prosopagnosia, a condition that is characterized by an impairment in the ability to recognize faces despite normal sensory vision and intelligence, might arise from a disruption to either and/or both the inferior longitudinal fasciculus (ILF) and IFOF (Thomas et al, 2009)

Summary

Introduction

The cerebral hemispheres of the human brain can be subdivided into two primary tissue types: the white matter and the gray matter (Fields, 2008a). Computational tractography refers to a collection of methods designed to make inferences about the macroscopic structure of white matter pathways (Figure 5C; Jbabdi et al, 2015; Wandell, 2016) These algorithms combine models of the local distribution of neuronal fascicle orientations across multiple voxels to track long-range neuronal pathways. Later, Kim et al (2006) explored white matter tracts between early visual cortex and category-selective regions by combining fMRI, dMRI, and deterministic tensor-based fiber tractography. They reported the estimates on several white matter tracts, including a tract connecting the primary visual cortex and the parahippocampal place area (PPA; Epstein & Kanwisher, 1998). The structure of VOF may have implications for how dorsal and ventral streams communicate to integrate spatial and categorical information: V3A and V3B are known to be selective for motion and binocular disparity (Ashida, Lingnau, Wall, & Smith, 2007; Backus, Fleet, Parker, & Heeger, 2001; Cottereau, McKee, Ales, & Norcia, 2011; Fischer, Bulthoff, Logothetis, & Bartels, 2012; Goncalves et al, 2015; Nishida, Sasaki, Murakami, Watanabe, & Tootell, 2003; Tootell et al, 1997; Tsao et al, 2003), and hV4 and VO-1 are selective for color (Brewer et al, 2005; Brouwer & Heeger, 2009; Goddard, Mannion, McDonald, Solomon, & Clifford, 2011; McKeefry & Zeki, 1997; Wade et al, 2002; Wade et al, 2008; Winawer & Witthoft, 2015)

Summary

Conclusions and future directions