| dc.description.abstract | The trigeminal somatosensory system conveys the sense of touch to the face. Most mammals have specialized tactile hairs, or whiskers, on their cheeks and chin that mediate tactile exploration of their environment. These whiskers are innervated by the trigeminal nerve, and the mechanosensory signals that nerve conveys are sent first to the trigeminal somatosensory nuclei in the brainstem (the principal sensory nucleus and the spinal trigeminal nucleus), relayed to the ventroposterior medial nucleus of the thalamus, and from there sent to the face region of the primary somatosensory cortex. This pathway is best studied in laboratory rodents, where the facial whiskers are represented in each of the stations in the brainstem, thalamus and cortex in an anatomically visible array of circular modules that represent each whisker in a one-to-one fashion. However, knowledge of this pathway in other mammals is lacking. Information on this pathway in other species is crucial to understanding whether the knowledge gained in the rodent system is applicable somatosensory organization in other mammals. Here, I investigate the trigeminal somatosensory specializations in three non-traditional research animals that, together, cover a broad array of phenotypes for facial touch. These are the California sea lion (Zalophus californianus), the star-nosed mole (Condylura cristata), and the northern greater galago (Otolemur garnetti). In each case, I compare what I learn to what is known in the laboratory rodents. I find the anatomically distinct segments are represented in various stations in all these mammals. This suggests that at the level of forming somatosensory maps of the periphery, particularly in the brainstem and thalamus, mammals share many of the same basic rules for brain organization. | |
