title: Subcortical barrelette-like and barreloid-like structures in the prosimian galago (Otolemur garnetti).
abstract: Galagos are prosimian primates that resemble ancestral primates more than most other extant primates. As in many other mammals, the facial vibrissae of galagos are distributed across the upper and lower jaws and above the eye. In rats and mice, the mystacial macrovibrissae are represented throughout the ascending trigeminal pathways as arrays of cytoarchitecturally distinct modules, with each module having a nearly one-to-one relationship with a specific facial whisker. The macrovibrissal representations are termed barrelettes in the trigeminal somatosensory brainstem, barreloids in the ventroposterior medial subnucleus of the thalamus, and barrels in primary somatosensory cortex. Despite the presence of facial whiskers in all nonhuman primates, barrel-like structures have not been reported in primates. By staining for cytochrome oxidase, Nissl, and vesicular glutamate transporter proteins, we show a distinct array of barrelette-like and barreloid-like modules in the principal sensory nucleus, the spinal trigeminal nucleus, and the ventroposterior medial subnucleus of the galago, Otolemur garnetti. Labeled terminals of primary sensory neurons in the brainstem and cell bodies of thalamocortically projecting neurons demonstrate that barrelette-like and barreloid-like modules are located in areas of these somatosensory nuclei that are topographically consistent with their role in facial touch. Serendipitously, the plane of section that best displays the barreloid-like modules reveals a remarkably distinct homunculus-like patterning which, we believe, is one of the clearest somatotopic maps of an entire body surface yet found.
authors.affiliation: Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37240;
authors.forename: Eva Kille
authors.initials: EK
authors.lastname: Sawyer
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, TN 37240;
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Liao
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, TN 37240;
authors.forename: Hui-Xin
authors.initials: HX
authors.lastname: Qi
authors.affiliation: Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA 02114; Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114;
authors.forename: Pooja
authors.initials: P
authors.lastname: Balaram
authors.affiliation: Department of Developmental Physiology, National Institute for Physiological Sciences, Aichi 444-8585, Japan; and Department of Psychology, University of Tartu, 50411 Tartu, Estonia.
authors.forename: Denis
authors.initials: D
authors.lastname: Matrov
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, TN 37240; jon.h.kaas@vanderbilt.edu.
authors.forename: Jon H
authors.initials: JH
authors.lastname: Kaas
mesh_terms: D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism; D009434:Neural Pathways / Q000166:cytology* / Q000502:physiology*; D009562:Nissl Bodies / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism; D011443:Strepsirhini / Q000033:anatomy & histology* / Q000502:physiology; D013788:Thalamus / Q000033:anatomy & histology* / Q000502:physiology; D014279:Trigeminal Nucleus, Spinal / Q000378:metabolism; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism; D014738:Vibrissae / Q000502:physiology*
chemical_list: D050496:Vesicular Glutamate Transport Proteins; D003576:Electron Transport Complex IV
keywords: barrel cortex; primate; somatosensory maps; trigeminal; vibrissa