2003 Fiscal Year Final Research Report Summary
Analysis of the brainstem neuronal network controlling laryngeal movements
| Project/Area Number |
14370538
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Chiba University |
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Principal Investigator |
SHIBA Keisuke Chiba University, University Hospital, Assistant, 医学部附属病院, 助手 (40291299)
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| Co-Investigator(Kenkyū-buntansha) |
UMEZAKI Toshiro Kyushu University, Hospital, Lecturer, 附属病院, 講師 (80223600)
NAKAZAWA Ken Chiba University, Graduate School of Medicine, Lecturer, 大学院・医学研究院, 講師 (10312943)
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| Project Period (FY) |
2002 – 2003
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| Keywords | larynx / thyroarytenoid muscle / multiple system atrophy / cat / laryngeal obstruction / 喉頭反射 |
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| Research Abstract |
1.We studied the patterns of membrane potential changes in vocal cord tensor motoneurons, i.e. cricothyroid muscle motoneurons (CTMs), during fictive breathing, vocalization, coughing, and swallowing in decerebrate paralyzed cats to determine the nature of central drives to CTMs during these behaviors. Our study revealed that the main role of the cricothyroid muscle is vocalization but the functional roles in coughing and swallowing are minor, and that the CTM activity during resting breathing and vocalization are primarily controlled by excitatory inputs, while during coughing and swallowing, inhibitory inputs play important roles in shaping membrane potential trajectories.
2.In patients with vocal cord abduction impairment, we investigated the role of the vocal cord adductor in generating dyspnea in laryngeal obstruction by recording its electromyographic activity and by observing vocal cord movement endoscopically under propofol anesthesia. The adductor was activated during inspirati
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on and the glottis was closed with laryngeal stridor. Because this adductor inspiratory activity was abolished by opening tracheostoma in tracheostomized patients, it is strongly suspected that this inspiratory adductor activity is induced by the airway reflex.
3.We hypothesized that an airway reflex attributable to insufficient opening of the glottis during inspiration causes this adductor inspiratory activity. To identify such airway reflex, we recorded the adductor electromyogram in the cat whose vocal cords were mechanically adducted under anesthesia. In these cats, the adductor was activated during inspiration with powerful negative pressure in the trachea. The adductor was activated by negative pressure in the subglottic space, but scarcely activated by in the lower airway. In addition, the adductor inspiratory activity in glottis-closed cats was usually abolished by laryngeal deafferentation. We conclude that the airway reflex triggered by subglottic negative pressure attributable to glottal narrowing during inspiration causes the adductor inspiratory activity similar to that in MSA patients. Less
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Research Products
(6 results)
