title: Thalamic afferent and efferent connectivity to cerebral cortical areas with direct projections to identified subgroups of trigeminal premotoneurons in the rat.
abstract: The roles of supramedullary brain mechanisms involved in the control of jaw movements are not fully understood. To address this issue, a series of retrograde (Fluorogold, FG) and anterograde (biotinylated dextran amine, BDA) tract-tracing studies were done in rats. At first, we identified projection patterns from defined sensorimotor cortical areas to subgroups of trigeminal premotoneurons that are located in defined brainstem areas. Focal injections of FG into these brainstem areas revealed that the rostralmost part of lateral agranular cortex (rmost-Agl), the rostralmost part of medial agranular cortex (rmost-Agm), and the rostralmost part of primary somatosensory cortex (rmost-S1) preferentially project to brainstem areas containing jaw-closing premotoneurons, jaw-opening premotoneurons and a mixture of both types of premotoneurons, respectively. The thalamic reciprocal connectivities to rmost-Agl, rmost-Agm, and rmost-S1 were then investigated following cortical injections of FG or BDA. We found many retrogradely FG-labeled neurons and large numbers of axons and terminals labeled anterogradely with BDA in the dorsal thalamus mainly on the side ipsilateral to the injection sites. The rmost-Agl had strong connections with the ventral lateral nucleus (VL), ventromedial nucleus (VM), parafascicular nucleus, and posterior nucleus (Po); the rmost-Agm with the ventral anterior nucleus, VL, VM, central lateral nucleus, paracentral nucleus, central medial nucleus, mediodorsal nucleus and Po; and the rmost-S1 with the ventral posteromedial nucleus and Po. The present results suggest that the descending multiple pathways from the cerebral cortex to jaw-closing and jaw-opening premotoneurons have unique functional roles in jaw movement motor control.
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Tahsinul
authors.initials: T
authors.lastname: Haque
authors.forename: Shinya
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Yuji
authors.initials: Y
authors.lastname: Masuda
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kato
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.forename: Katsuro
authors.initials: K
authors.lastname: Uchino
authors.forename: Ayaka
authors.initials: A
authors.lastname: Oka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakamura
authors.forename: Rieko
authors.initials: R
authors.lastname: Takeda
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ono
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Kogo
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives; D001933:Brain Stem / Q000166:cytology / Q000502:physiology; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D003911:Dextrans; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D008297:Male; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D009476:Neurons, Efferent / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology; D013788:Thalamus / Q000166:cytology / Q000502:physiology*; D014278:Trigeminal Nuclei / Q000166:cytology / Q000502:physiology*
chemical_list: D003911:Dextrans; D005456:Fluorescent Dyes; C076397:biotinylated dextran amine; D001710:Biotin