ELSC Special Seminar: June 6th, 2019

ELSC cordially invites you to the lecture given by:

 

Dr. Hiromasa Takemura 

CiNet, National Institute of Information and Communications Technology 

 

On the topic of:

“Using diffusion-weighted MRI to measure white matter pathways in the visual system”

 

 

The lecture will be held on Thursday, June 6th, at 11:00

at ELSC: Becker Auditorium, Goodman Brain Sciences Building

Edmond J. Safra Campus

 

Light refreshments at 10:45

 

Host: Dr. Aviv Mezer

 

The visual system is composed of a number of white matter pathways, which support communication between distinct visual areas. Recent progress in diffusion-weighted MRI (dMRI) and tractography opens a new avenue to study trajectories and tissue properties of white matter pathways from living humans. This talk describes recent progress in analyzing these pathways to understand disorders, organization and function of the visual system by primarily using diffusion-weighted MRI (dMRI) and tractography. First, I will describe a study using multi-contrast MRI approach (dMRI and quantitative MRI) to measure tissue properties of early visual white matter pathways in retinal disease patients. Specifically, we demonstrate that multi-contrast MRI will provide useful information to interpret microstructural properties of trans-synaptic tissue changes in the optic radiation as a consequence of retinal ganglion cell disease, Leber’s hereditary optic neuropathy. Second, I will describe recent progress in analyzing the relatively unstudied visual white matter pathways, vertical occipital fasciculus (VOF; Yeatman et al., 2014) by combining dMRI and anatomical measurements. While the VOF is an important pathway to understand human visual processing because it connects dorsal and ventral visual streams (Takemura et al., 2016), it attracts little attention as compared with the anteroposterior pathways that shape the parallel dorsal and ventral streams emphasized in tracer-based wiring diagrams (Wallisch and Movshon 2008). To improve our understanding of this pathway, we first analyzed high-resolution dMRI data obtained from non-human primate brains. The analysis of dMRI data reveals that VOF is a common prominent feature of the occipital white matter among primate species, and also supports a consistency between dMRI measurement on VOF and invasive anatomical studies. The analysis of VOF with visual field map also suggests that VOF is an essential pathway for integrating upper and lower visual field information, which is separately represented in dorsal and ventral V2/V3. Furthermore, I will also describe an analysis of data obtained by using polarized light imaging (PLI; Axer et al., 2011), which provide fiber orientation at micrometer resolution. PLI data not only supports the existence of the VOF, but also disentangles current controversies in the visual white matter pathways, such that how much the VOF is distinct from a pathway connecting occipital and inferotemporal cortex. Finally, I will discuss recent work comparing human VOF tissue properties and human perceptual performance in depth perception measured by psychophysical experiment.

When