Hypothalamic and cortical control of jaw reflexes

The subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used...

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Main Author: Olsson, Kurt Å.
Format: Doctoral Thesis
Language:English
Published: Umeå universitet, Fysiologi 1979
Subjects:
Cat
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-73597
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spelling ndltd-UPSALLA1-oai-DiVA.org-umu-735972013-06-26T04:04:51ZHypothalamic and cortical control of jaw reflexesengOlsson, Kurt Å.Umeå universitet, FysiologiUmeå : Umeå universitet1979CatOral projectionsCerebral cortexCytoarchitectureHypothalamusDefence-Attack areaJaw reflexesBruxismMyofascial pain dysfunctionThe subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used for the experiments. Ipsi- and contralateral nerves from the oral cavity and the face were stimulated electrically. Cortical potentials were averaged and recorded. The location of the projections was related to the cytoarchi-tectonic areas of the cerebral cortex. It was found that the afferents projected to separate maximum points in areas 3a, 3b, 5a and 6aß. The projections to areas 3a and 3b were somatotopically organized, but the layout of the projections on the cortex was not facelike.The effect of monopolar anodal stimulation of the cerebral cortex on the monosynaptic jaw closing and the di synaptic jaw opening reflexes was investigated. A sequence of facilitation and inhibition of both reflexes was elicited by cortical stimulation. The effects were of short latency (2.5 ms) and could start with either facilitation or inhibition. The timecourse of the sequence was sinuslike with a period of 10 ms. The largest effect originated in the "sensory" areas 3a and 3b and not in the "motor" areas 4y and 6ag. It is suggested, that a tri gemino-cortico-tri geminai loop via area 3a may function in reflex modulation of jaw movements.The hypothalamic effects on the jaw reflexes were evoked by electrical stimulation in those parts of the hypothalamus, which are w known to generate defence, attack or feeding responses. A tenfold facilitation of the jaw closing reflex and a facilitation followed by almost complete inhibition of the jaw opening reflex were observed in the anaesthetized animal with intact cerebral cortex. The effects remained but were diminished in amplitude after cortical ablation. The descending path was located in the ventral midbrain tegmentum.It is suggested that the observed hypothalamo-tri geminai mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set points of the biting force and the rest position. The implications of this hypothesis on the etiology of bruxism and the myofascial pain-dysfunction are discussed. <p>Härtill 3 rapporter.</p>digitalisering@umuDoctoral thesis, comprehensive summaryinfo:eu-repo/semantics/doctoralThesistexthttp://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-73597Umeå University medical dissertations, 0346-6612 ; New series 52application/pdfinfo:eu-repo/semantics/openAccess
collection NDLTD
language English
format Doctoral Thesis
sources NDLTD
topic Cat
Oral projections
Cerebral cortex
Cytoarchitecture
Hypothalamus
Defence-Attack area
Jaw reflexes
Bruxism
Myofascial pain dysfunction
spellingShingle Cat
Oral projections
Cerebral cortex
Cytoarchitecture
Hypothalamus
Defence-Attack area
Jaw reflexes
Bruxism
Myofascial pain dysfunction
Olsson, Kurt Å.
Hypothalamic and cortical control of jaw reflexes
description The subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used for the experiments. Ipsi- and contralateral nerves from the oral cavity and the face were stimulated electrically. Cortical potentials were averaged and recorded. The location of the projections was related to the cytoarchi-tectonic areas of the cerebral cortex. It was found that the afferents projected to separate maximum points in areas 3a, 3b, 5a and 6aß. The projections to areas 3a and 3b were somatotopically organized, but the layout of the projections on the cortex was not facelike.The effect of monopolar anodal stimulation of the cerebral cortex on the monosynaptic jaw closing and the di synaptic jaw opening reflexes was investigated. A sequence of facilitation and inhibition of both reflexes was elicited by cortical stimulation. The effects were of short latency (2.5 ms) and could start with either facilitation or inhibition. The timecourse of the sequence was sinuslike with a period of 10 ms. The largest effect originated in the "sensory" areas 3a and 3b and not in the "motor" areas 4y and 6ag. It is suggested, that a tri gemino-cortico-tri geminai loop via area 3a may function in reflex modulation of jaw movements.The hypothalamic effects on the jaw reflexes were evoked by electrical stimulation in those parts of the hypothalamus, which are w known to generate defence, attack or feeding responses. A tenfold facilitation of the jaw closing reflex and a facilitation followed by almost complete inhibition of the jaw opening reflex were observed in the anaesthetized animal with intact cerebral cortex. The effects remained but were diminished in amplitude after cortical ablation. The descending path was located in the ventral midbrain tegmentum.It is suggested that the observed hypothalamo-tri geminai mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set points of the biting force and the rest position. The implications of this hypothesis on the etiology of bruxism and the myofascial pain-dysfunction are discussed. === <p>Härtill 3 rapporter.</p> === digitalisering@umu
author Olsson, Kurt Å.
author_facet Olsson, Kurt Å.
author_sort Olsson, Kurt Å.
title Hypothalamic and cortical control of jaw reflexes
title_short Hypothalamic and cortical control of jaw reflexes
title_full Hypothalamic and cortical control of jaw reflexes
title_fullStr Hypothalamic and cortical control of jaw reflexes
title_full_unstemmed Hypothalamic and cortical control of jaw reflexes
title_sort hypothalamic and cortical control of jaw reflexes
publisher Umeå universitet, Fysiologi
publishDate 1979
url http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-73597
work_keys_str_mv AT olssonkurta hypothalamicandcorticalcontrolofjawreflexes
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