title: Electrophysiological and morphological properties of rat supratrigeminal premotor neurons targeting the trigeminal motor nucleus.
abstract: The electrophysiological and morphological characteristics of premotor neurons in the supratrigeminal region (SupV) targeting the trigeminal motor nucleus (MoV) were examined in neonatal rat brain stem slice preparations with Ca(2+) imaging, whole cell recordings, and intracellular biocytin labeling. First, we screened SupV neurons that showed a rapid rise in intracellular free Ca(2+) concentration ([Ca(2+)]i) after single-pulse electrical stimulation of the ipsilateral MoV. Subsequent whole cell recordings were generated from the screened SupV neurons, and their antidromic responses to MoV stimulation were confirmed. We divided the antidromically activated premotor neurons into two groups according to their discharge patterns during the steady state in response to 1-s depolarizing current pulses: those firing at a frequency higher (HF neurons, n = 19) or lower (LF neurons, n = 17) than 33 Hz. In addition, HF neurons had a narrower action potential and a larger afterhyperpolarization than LF neurons. Intracellular labeling revealed that the axons of all HF neurons (6/6) and half of the LF neurons (4/9) entered the MoV from its dorsomedial aspect, whereas the axons of the remaining LF neurons (5/9) entered the MoV from its dorsolateral aspect. Furthermore, the dendrites of three HF neurons penetrated into the principal sensory trigeminal nucleus (Vp), whereas the dendrites of all LF neurons were confined within the SupV. These results suggest that the types of SupV premotor neurons targeting the MoV with different firing properties have different dendritic and axonal morphologies, and these SupV neuron classes may play unique roles in diverse oral motor behaviors, such as suckling and mastication.
authors: Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan; and.
authors: Shiro
authors: S
authors: Nakamura
authors: Kiyomi
authors: K
authors: Nakayama
authors: Ayako
authors: A
authors: Mochizuki
authors: Fumihiko
authors: F
authors: Sato
authors: Tahsinul
authors: T
authors: Haque
authors: Atsushi
authors: A
authors: Yoshida
authors: Tomio
authors: T
authors: Inoue
mesh_terms: D000200:Action Potentials; D000818:Animals; D020013:Calcium Signaling; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D066266:Trigeminal Motor Nucleus / Q000166:cytology / Q000502:physiology*
keywords: Ca2+ imaging; discharge pattern; intracellular labeling; patch clamp; supratrigeminal region