title: Distribution of premotoneurons for jaw-closing and jaw-opening motor nucleus receiving contacts from axon terminals of primary somatosensory cortical neurons in rats.
abstract: To clarify features of direct projections from the primary somatosensory cortex (S1) to premotoneurons for the jaw-closing (JC) and jaw-opening (JO) components of the trigeminal motor nucleus, biotinylated dextranamine (BDA) and Fluorogold (FG) were used as the anterograde and retrograde tracers. The BDA and FG injections were made in the S1 and the JC or JO component, respectively, in rats. The distribution of FG-labeled JC and JO premotoneurons receiving contact(s) from BDA-labeled axon terminals of S1 neurons was quantitatively examined; the contacts were identified microscopically by using a X100 oil immersion objective. The largest and second largest numbers of JC and JO premotoneurons with contact(s) were found in the lateral reticular formation at the levels of the caudal pons and the medulla oblongata (cpmLRt) and trigeminal oral nucleus (Vo) bilaterally, and they comprised about 80% of the total premotoneurons with contact(s). The percentage of premotoneurons with contact(s) was higher in the Vo than in the cpmLRt for both JC and JO premotoneurons. Most of the JC or JO premotoneurons found in the nucleus of the solitary tract, inter- and supratrigeminal regions, mesencephalic trigeminal nucleus, parabrachial nucleus and reticular formation medial to the JO component of the trigeminal motor nucleus hardly received contact(s) from S1 neurons. This suggests that the contribution of S1 to the control of jaw movements is mediated via JC and JO premotoneurons located primarily in the cpmLRt and Vo areas of the brainstem.
authors.affiliation: Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Chang
authors.forename: Tahsinul
authors.initials: T
authors.lastname: Haque
authors.forename: Chie
authors.initials: C
authors.lastname: Iida
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Seki
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kato
authors.forename: Katsuro
authors.initials: K
authors.lastname: Uchino
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ono
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yong-Chul
authors.initials: YC
authors.lastname: Bae
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D007568:Jaw / Q000294:innervation* / Q000502:physiology*; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology; D017729:Presynaptic Terminals / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000502:physiology*