Identification of spinothalamic tract and its related thalamocortical fibers in human brain.

Little is known about the spinothalamic tract (STT) and its related thalamocortical fibers. In the current study, we attempted to identify the STT and related thalamocortical fibers in the human brain, using diffusion tensor tractography (DTT). We recruited 23 healthy volunteers for this study. Diffusion tensor images (DTIs) were scanned using 1.5-T, and the STT and medial lemniscus (ML) were obtained using FMRIB software. Normalized DTI tractography was reconstructed using the Montreal Neurological Institute (MNI) echo-planar imaging (EPI) template supplied with the SPM. The STT began at the posterolateral medulla and ascended to the ventral posterior-lateral (VPL) nucleus of the thalamus, through the pontine tegmentum posterolateral to the ML, and through the mesencephalic tegmentum posterior to the ML. STT-related thalamocortical fibers originated from the VPL nucleus of the thalamus and ascended through the posterior limb of the internal capsule and the posterior portion of the corona radiata, terminating at the primary somatosensory cortex. We identified the STT and its related thalamocortical fibers using DTT. These results would be helpful in the clinical field and also in research on somatosensory function in the human brain.