The rubrospinal tract in the human brain: diffusion tensor imaging study.

The rubrospinal tract (RST) is an extrapyramidal motor pathway in the human brain. In this study, using diffusion tensor tractography (DTT), we attempted to identify the RST in the normal human brain. Twenty-one healthy volunteers were recruited for this study. A 1.5-T scanner was used for scanning of diffusion tensor images, and the RSTs were isolated by DTT using FMRIB software. Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume of the RSTs were measured. Among 42 hemispheres of 21 subjects, RSTs were isolated in 27 hemispheres (64.28%) of 15 subjects. All identified tracts originated from the red nucleus and crossed the midline via ventral tegmental decussation. Then, they passed through the area between the inferior olivary nucleus and the inferior cerebellar peduncle in the contralateral medulla. The tracts finally descended through the lateral funiculus of the upper spinal cord. Mean values of FA, MD, and tract volume did not differ significantly between the left and right hemispheres (P>0.05). We believe that the methodologies used and the results of this study would be helpful to researchers interested in the function of the human RST and its clinical implications.