title: Generation of the masticatory central pattern and its modulation by sensory feedback.
abstract: The basic pattern of rhythmic jaw movements produced during mastication is generated by a neuronal network located in the brainstem and referred to as the masticatory central pattern generator (CPG). This network composed of neurons mostly associated to the trigeminal system is found between the rostral borders of the trigeminal motor nucleus and facial nucleus. This review summarizes current knowledge on the anatomical organization, the development, the connectivity and the cellular properties of these trigeminal circuits in relation to mastication. Emphasis is put on a population of rhythmogenic neurons in the dorsal part of the trigeminal sensory nucleus. These neurons have intrinsic bursting capabilities, supported by a persistent Na(+) current (I(NaP)), which are enhanced when the extracellular concentration of Ca(2+) diminishes. Presented evidence suggest that the Ca(2+) dependency of this current combined with its voltage-dependency could provide a mechanism for cortical and sensory afferent inputs to the nucleus to interact with the rhythmogenic properties of its neurons to adjust and adapt the rhythmic output. Astrocytes are postulated to contribute to this process by modulating the extracellular Ca(2+) concentration and a model is proposed to explain how functional microdomains defined by the boundaries of astrocytic syncitia may form under the influence of incoming inputs.
authors.affiliation: Groupe de Recherche sur le Système Nerveux Central du FRSQ, Université de Montréal and Faculté de médecine dentaire, Université de Montréal, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Morquette
authors.forename: Raphaël
authors.initials: R
authors.lastname: Lavoie
authors.forename: Mitch-David
authors.initials: MD
authors.lastname: Fhima
authors.forename: Xavier
authors.initials: X
authors.lastname: Lamoureux
authors.forename: Dorly
authors.initials: D
authors.lastname: Verdier
authors.forename: Arlette
authors.initials: A
authors.lastname: Kolta
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000502:physiology*; D056228:Feedback, Sensory / Q000502:physiology*; D006801:Humans; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D013284:Stomatognathic System / Q000166:cytology / Q000294:innervation* / Q000502:physiology; D014276:Trigeminal Nerve / Q000166:cytology / Q000502:physiology*