title: Termination differences in the primary sensorimotor cortex between the medial lemniscus and spinothalamic pathways in the human brain.
abstract: The medial lemniscus (ML) and its thalamocortical pathway is responsible for proprioception, in contrast, the spinothalamic tract (ST) and its thalamocortical pathway is the neural tract for pain and body temperature. Therefore, the ML pathway plays a crucial role in skillful movements and may be more linked to motor function than the ST pathway. We investigated the differences in the distribution of the primary motor cortex (M1) and the primary somatosensory cortex (S1) between the ML and ST pathways. Adults (mean age: 40.4 years, range: 21-61 years) were recruited for this study. The seed masks for the ML and ST pathways were given on the color map of the medulla according to the known anatomy and waypoint masks were placed on the ventro-postero-lateral nucleus of the thalamus. The volume of ML pathway did not show any difference between the M1 (10.94) and S1 (13.02) (p>0.05). By contrast, the mean voxel number of the ST pathway in the M1 (18.25) and S1 (27.38) showed significant difference between the M1 and S1 (p<0.05). As for relative voxel number percentage of the M1 compared to the S1, the ML pathway (84%) was significantly higher than ST pathway (67%) (p<0.05). We found that more neural fibers of the ML pathway were terminated in the M1 relative to the S1 compared to the SLP, and this may be linked to the inherent execution of movements of the M1.
authors.affiliation: Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Republic of Korea.
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Jang
authors.forename: Yong Hyun
authors.initials: YH
authors.lastname: Kwon
authors.forename: Mi Young
authors.initials: MY
authors.lastname: Lee
authors.forename: Dong Yeop
authors.initials: DY
authors.lastname: Lee
authors.forename: Ji Heon
authors.initials: JH
authors.lastname: Hong
mesh_terms: D000328:Adult; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000033:anatomy & histology*; D013003:Somatosensory Cortex / Q000033:anatomy & histology*; D013116:Spinal Cord / Q000033:anatomy & histology*; D013133:Spinothalamic Tracts / Q000033:anatomy & histology*; D013788:Thalamus / Q000033:anatomy & histology*; D055815:Young Adult