The specific aims of this proposal are to elucidate the brain stem neurophysiological and neuropharmacological mechanisms controlling rhythmical jaw movements (RJMs), resembling mastication, in the guinea pig. We propose to characterize the pharmacological mechanisms controlling jaw opener (digastric) motoneuron and premotoneuron excitability during RJMs elicited by electrical stimulation of the cortex (or pyramidal tract), and during RJMs elicited by systemic administration of a dopamine agonist, apomorphine (APO). The project is divided into three parts. Parts one and two will focus on recording extracellularly from digastric motoneurons (DIG) or pre-motoneurons, respectively, during cortically induced RJMs while simultaneously applying to the cell, through micropipettes, small quantities of putative neurotransmitter (NT) agonists and antagonists. Finally, part three will investigate the neurophysiological and neuropharmacological mechanisms controlling these same cell populations during RJMs induced by APO administration. The long-term goal is to understand both the mechanisms underlying the central nervous system control of normal rhythmic jaw movements that occur during activities such as feeding and drinking, as well as the abnormal, involuntary rhythmic jaw movements occurring in disorders such as tardive dyskinesia and bruxism. Tardive dyskinesia is a movement disorder characterized by uncontrolled rhythmic jaw movements of oral-facial structures that result from long term administration of neuroleptic drugs. Bruxism, the grinding or clenching of teeth in sleep, is another uncontrolled jaw movement behavior that often leads to the myofacial pain-dysfunction syndrome. The etiology of the generation of these abnormal jaw movements in unknown, although brusixm is thought to be related to stress, and tardive dyskinesia to a disruption of dopamine activity in the basal ganglia. The results of the proposed experiments in the guinea pig will provide insights into the neurophysiological and neuropharmacological mechanisms underlying the production of involuntary rhythmic jaw movements in humans.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
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Neurology B Subcommittee 1 (NEUB)
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University of California Los Angeles
Schools of Arts and Sciences
Los Angeles
United States
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Tsuruyama, Kentaro; Hsiao, Chie-Fang; Chandler, Scott H (2013) Participation of a persistent sodium current and calcium-activated nonspecific cationic current to burst generation in trigeminal principal sensory neurons. J Neurophysiol 110:1903-14
Hsiao, Chie-Fang; Kaur, Gurvinder; Vong, Angela et al. (2009) Participation of Kv1 channels in control of membrane excitability and burst generation in mesencephalic V neurons. J Neurophysiol 101:1407-18
Hsiao, Chie-Fang; Gougar, Kelly; Asai, J et al. (2007) Intrinsic membrane properties and morphological characteristics of interneurons in the rat supratrigeminal region. J Neurosci Res 85:3673-86
Enomoto, Akifumi; Han, Juliette M; Hsiao, Chie-Fang et al. (2007) Sodium currents in mesencephalic trigeminal neurons from Nav1.6 null mice. J Neurophysiol 98:710-9
Enomoto, Akifumi; Han, Juliette M; Hsiao, Chie-Fang et al. (2006) Participation of sodium currents in burst generation and control of membrane excitability in mesencephalic trigeminal neurons. J Neurosci 26:3412-22
Tanaka, Susumu; Chandler, Scott H (2006) Serotonergic modulation of persistent sodium currents and membrane excitability via cyclic AMP-protein kinase A cascade in mesencephalic V neurons. J Neurosci Res 83:1362-72
Wu, Nanping; Enomoto, Akifumi; Tanaka, Susumu et al. (2005) Persistent sodium currents in mesencephalic v neurons participate in burst generation and control of membrane excitability. J Neurophysiol 93:2710-22
Hsiao, Chie-Fang; Wu, Nanping; Chandler, Scott H (2005) Voltage-dependent calcium currents in trigeminal motoneurons of early postnatal rats: modulation by 5-HT receptors. J Neurophysiol 94:2063-72
Tanaka, Susumu; Wu, Nanping; Hsaio, Chie-Fang et al. (2003) Development of inward rectification and control of membrane excitability in mesencephalic v neurons. J Neurophysiol 89:1288-98
Hsiao, Chie-Fang; Wu, Nanping; Levine, Michael S et al. (2002) Development and serotonergic modulation of NMDA bursting in rat trigeminal motoneurons. J Neurophysiol 87:1318-28

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