Longchuan Li1, Matthew F. Glasser2, Todd M. Preuss3, James K. Rilling3, Frederick W. Damen4, Xiaoping Hu1
1School of Medicine, Emory University/Gerogia Institute of Technology, Atlanta, GA, United States; 2Department of Anatomy and Neurobiology,, Washington University, St Louis, MO, United States; 3Center for Translational and Social Neuroscience, Emory University, Atlanta, GA, United States; 4Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States
Tracing studies in primates show that the primary motor cortex exhibits homotopic callosal projections, with (1) the strength of the callosal projections showing a medial to lateral gradient and (2) sectors of M1 having the densest connection with the homotopic contralateral sectors. Here we used two advanced tractography algorithms to trace these fibers in humans to see whether they replicate the observations in primates. While the medial sector showed significant stronger connections, the densest homotopic projection to the contralateral sectors were not observed in our results, indicating the need for more robust tractography methods for quantitative brain mapping studies.