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NMDA-induced rhythmical activities of the hypoglossal motoneuron in an in vitro brainstem-spinal cord preparation from newborn rats
1615
DISCHARGE PATTERN OF MESENCEPHALIC TRIGEMINAL NEURONS DURING CHEWING IN THE RABBITS. OSAMU NAKAMURA, YUJI MASUDA, TAKAFUMI KATOH, JUNZO MIZUNO, TOM10 INOUE, RYUJI MATSUO AND TOSHIFUMI MORIMOTO Dept. of Oral Phvsiol..Osaka Univ. Facultv of Dentistrv, l-8 Yamadaoka. Suita. Osaka 565, Japan
This study aims to understand how muscle spindles in the jaw-closing muscle contribute to the control of jaw-closing muscle activity during mastication. we recorded discharges of the mesencephalic trigeminal neurons, masseteric and digastric EMG activities and jaw movements simultaneouslyduring cortically induced rhythmic jaw movements(CRJMs) in the anesthetized rabbit. Test materials of polyurethane foam with different hardness were inserted between the opposing molars during CRJ?Q. All recorded neurons discharged rhythmically in relation to jaw movements. Their discharge patterns varied with the hardness of test materials, e.g., most neurons increased their firing frequency during the jaw-closing phase with increase in the hardness of the materials, and some neurons began to fire at the jaw closing phase. These results are also compared with those obtained during chewing foods with various properties in the awake rabbit.
1616
NMDA-INDUCED RHYTHMICAL ACTIVITIES OF THE HYPOGLOSSAL MOTONEURON IN AN lN VITRO BRAINSTEM-SPINAL CORD PREPARATION FROM NEWBORN RATS. NOBUO KATAKUKA. LIA JIA AND YOSHIO NAKAMURA, Dem. of Phvsiol.. Facult. of Dent.. Tokvo Med. Dent. Univ.. Bunkvo-ku. Tokvo 113. Janan.
We tried to induce rhythmical oro-facial motor activities in an isolated brain of mammals, using an in &uo brainstern-. spinal cord preparation with or without tongue from newborn rats (from 0 to 4 day-old) in a modified Krebs solution at 25’C equilibrated with 95% Oz-5% COz. Neural activities were monitored from the hypoglossal (XII) nerve as well as the ventral roots of the cervical spinal cord (C4-C5) with suction electrodes, and EMG was recorded from the tongue muscle with wire electrodes. Bath application of various neurochemical compounds revealed the following results: (I) rhythmical burst activities were induced in the XII nerve and in the tongue muscle after application of N-methyl-D-aspartate (NMDA) or glutamate; (2) these rhythmical activities were distinct from spontaneously generated respiratory activities in XIIandC4.5. unsynchronized withrespiration, andhada shorter cycle length (from 2.5 to 6.0 seconds)than that ofrespiration (more than 10.0 seconds); (3) the NMDA- or glutamate-induced rhythmical activities were completely blocked with simultaneous application of 2-amino-5-phosphonovalerate (APV). The results demonstrate that, in an isolated brainstem-spinal cord preparation from newborn rats, NMDA can induce rhythmical activities different from respiration in the XIImotoneurons. Thisinvitro preparation will be useful for the investigation of neural mechanisms underlying the central rhythm generation of feeding movements including sucking.
1617
DISTINCT MOTOR PATTERNS OF CRICOTHYROID MUSCLE IN LARYNX EVOKED BY ELECTRICAL STIMULATION IN AMYGDALA AND LATERAL HYPOTHALAMUS. HIDEHO ARITA, ICHIRO KITA AND MASAHIRO SAKAMOTO, 1st. Dept. of Physiol., Toho Univ. Sch. of Med., Omori-nishi, Ota, Tokyo 143, Faculty of Foreign Languages, Hokuriku Univ., Kanazawa 920-l 1.
We evaluated distinct effects of electrical stimulation of the central amygdaloid nucleus and of the lateral hypothalamus on behavioral motor control of cricothyroid (CT) muscle of the larynx in anesthetized rats. CT exhibited only inspiratory activity during quiet breathing. Tonic electrical stimulation in the central amygdaloid nucleus produced phaslc CT activity restricted to the early expiratory cycle: this recruited expiratory unit lasted a few minutes after cessation of the stimulation. This was accompanied by suppression of inspiratory activity of the mtercostal muscle, indicating motor pattern of holding breath or breaking expiratory flow. By contrast, tonic electrical stimulation in the lateral hypothalamus evoked phasic CT activity restricted to the late expiratory cycle, accompanied by recruitment of expiratory activity of abdominal muscle and by augmented inspiratory activity of the intercostal muscle. This motor pattern was considered to be involved in vocalization. The present results reveals distinct role of the central amygdaloid nucleus and the lateral hypothalamus in behavioral control of CT muscle of the larynx.
DISCHARGE PATTERN OF MESENCEPHALIC TRIGEMINAL NEURONS DURING CHEWING IN THE RABBITS. OSAMU NAKAMURA, YUJI MASUDA, TAKAFUMI KATOH, JUNZO MIZUNO, TOM10 INOUE, RYUJI MATSUO AND TOSHIFUMI MORIMOTO Dept. of Oral Phvsiol..Osaka Univ. Facultv of Dentistrv, l-8 Yamadaoka. Suita. Osaka 565, Japan
This study aims to understand how muscle spindles in the jaw-closing muscle contribute to the control of jaw-closing muscle activity during mastication. we recorded discharges of the mesencephalic trigeminal neurons, masseteric and digastric EMG activities and jaw movements simultaneouslyduring cortically induced rhythmic jaw movements(CRJMs) in the anesthetized rabbit. Test materials of polyurethane foam with different hardness were inserted between the opposing molars during CRJ?Q. All recorded neurons discharged rhythmically in relation to jaw movements. Their discharge patterns varied with the hardness of test materials, e.g., most neurons increased their firing frequency during the jaw-closing phase with increase in the hardness of the materials, and some neurons began to fire at the jaw closing phase. These results are also compared with those obtained during chewing foods with various properties in the awake rabbit.
1616
NMDA-INDUCED RHYTHMICAL ACTIVITIES OF THE HYPOGLOSSAL MOTONEURON IN AN lN VITRO BRAINSTEM-SPINAL CORD PREPARATION FROM NEWBORN RATS. NOBUO KATAKUKA. LIA JIA AND YOSHIO NAKAMURA, Dem. of Phvsiol.. Facult. of Dent.. Tokvo Med. Dent. Univ.. Bunkvo-ku. Tokvo 113. Janan.
We tried to induce rhythmical oro-facial motor activities in an isolated brain of mammals, using an in &uo brainstern-. spinal cord preparation with or without tongue from newborn rats (from 0 to 4 day-old) in a modified Krebs solution at 25’C equilibrated with 95% Oz-5% COz. Neural activities were monitored from the hypoglossal (XII) nerve as well as the ventral roots of the cervical spinal cord (C4-C5) with suction electrodes, and EMG was recorded from the tongue muscle with wire electrodes. Bath application of various neurochemical compounds revealed the following results: (I) rhythmical burst activities were induced in the XII nerve and in the tongue muscle after application of N-methyl-D-aspartate (NMDA) or glutamate; (2) these rhythmical activities were distinct from spontaneously generated respiratory activities in XIIandC4.5. unsynchronized withrespiration, andhada shorter cycle length (from 2.5 to 6.0 seconds)than that ofrespiration (more than 10.0 seconds); (3) the NMDA- or glutamate-induced rhythmical activities were completely blocked with simultaneous application of 2-amino-5-phosphonovalerate (APV). The results demonstrate that, in an isolated brainstem-spinal cord preparation from newborn rats, NMDA can induce rhythmical activities different from respiration in the XIImotoneurons. Thisinvitro preparation will be useful for the investigation of neural mechanisms underlying the central rhythm generation of feeding movements including sucking.
1617
DISTINCT MOTOR PATTERNS OF CRICOTHYROID MUSCLE IN LARYNX EVOKED BY ELECTRICAL STIMULATION IN AMYGDALA AND LATERAL HYPOTHALAMUS. HIDEHO ARITA, ICHIRO KITA AND MASAHIRO SAKAMOTO, 1st. Dept. of Physiol., Toho Univ. Sch. of Med., Omori-nishi, Ota, Tokyo 143, Faculty of Foreign Languages, Hokuriku Univ., Kanazawa 920-l 1.
We evaluated distinct effects of electrical stimulation of the central amygdaloid nucleus and of the lateral hypothalamus on behavioral motor control of cricothyroid (CT) muscle of the larynx in anesthetized rats. CT exhibited only inspiratory activity during quiet breathing. Tonic electrical stimulation in the central amygdaloid nucleus produced phaslc CT activity restricted to the early expiratory cycle: this recruited expiratory unit lasted a few minutes after cessation of the stimulation. This was accompanied by suppression of inspiratory activity of the mtercostal muscle, indicating motor pattern of holding breath or breaking expiratory flow. By contrast, tonic electrical stimulation in the lateral hypothalamus evoked phasic CT activity restricted to the late expiratory cycle, accompanied by recruitment of expiratory activity of abdominal muscle and by augmented inspiratory activity of the intercostal muscle. This motor pattern was considered to be involved in vocalization. The present results reveals distinct role of the central amygdaloid nucleus and the lateral hypothalamus in behavioral control of CT muscle of the larynx.