Le système trigéminal –tout comme l’olfaction et la gustation– est un sens chimique qui permet la perception des informations chimiosensorielles de notre environnement. Contrairement à l’olfaction et à la gustation, notre connaissance du traitement des mélanges par le système trigéminal est limitée. Nous avons donc utilisé des mélanges de trois agonistes relativement spécifiques à des récepteurs (eucalyptol, agoniste TRPM8; aldéhyde cinnamique, agoniste TRPA1 ; camphre, agoniste TRPV1) et d’une odeur pure (alcool phényléthylique) dans différentes proportions afin de déterminer les dimensions de base de la perception trigéminale. Quatre dimensions principales se sont avérées pertinentes: l’intensité, la sensation de chaleur, la sensation de froid et la douleur. Nous avons utilisé ces dimensions pour étudier la perception de mélanges et de combinaisons dans différentes proportions d’un stimulus qui procure une sensation de froid (eucalyptol) et d’un stimulus qui procure une sensation de chaleur (aldéhyde cinnamique). Les résultats indiquent que les mélanges obtiennent généralement des scores plus élevés que les combinaisons sur les dimensions « intensité », « sensation de chaleur » et « douleur » alors que les combinaisons obtiennent des scores plus élevés sur la dimension « sensation de froid ». Ces résultats suggèrent des interactions spécifiques pour les différentes dimensions de la perception trigéminale. Nous en venons à la conclusion d’un effet d’additivité pour les mélanges sur les dimensions « intensité », « sensation de chaleur » et « douleur » alors que nous observons plutôt un effet de suppression de la perception de froid pour les deux stimuli dans les mélanges, ce qui semble indiquer des interactions particulières pouvant prendre place aux niveaux périphérique ou central. / The trigeminal system – along with smell and taste – is a chemical sense that allows the perception of chemosensory information in our environment. However, contrary to smell and taste, we lack knowledge of the trigeminal processing of mixtures. We therefore investigated trigeminal perception using mixtures of three relatively receptor specific agonists (eucalyptol, TRPM8 agonist; cinnamaldehyde, TRPA1 agonist and camphor, TRPV1 agonist) together with one control odor (phenyl ethyl alcohol or PEA) in different proportions to determine basic dimensions of trigeminal perception. Four main dimensions were proven relevant to trigeminal perception: intensity, warmth sensation, cold sensation and pain sensation. Subsequently, we used these dimensions to investigate perception of mixtures and combinations of trigeminal stimuli using different concentrations of a cooling stimulus (eucalyptol) with a stimulus which evokes warmth perception (cinnamaldehyde). Results showed mixtures generally yielded higher ratings than combinations on the trigeminal dimensions “intensity”, “warm” and “painful” whereas combinations yielded higher ratings than mixtures on the trigeminal dimension “cold”. These results suggest dimension specific interactions in the perception of trigeminal mixtures. For the mixtures we used, we reach the conclusion of additivity for the dimensions “intensity”, “warm” and “painful”; we observed suppression of the cold perception of both stimuli in mixtures suggesting particular interactions which may take place on peripheral or central levels.

A maioria dos pacientes que têm dor de origem dentária pulpar ou periapical tem dor referida, e algumas características da dor parecem influenciar este fenômeno. Por meio do preenchimento de fichas clínicas, com informações sobre as características da dor, investigamos, em 60 voluntários, a distribuição topográfica de áreas de dor referida de origem dentária. Por meio de métodos psicofísicos, comparamos a resolução espacial da dor com a resolução espacial de outras modalidades somestésicas (mecânica e térmica). Nossos resultados indicam que a intensidade da dor favorece o fenômeno da dor referida e interfere na sua dispersão topográfica. Dentes algógenos com polpa viva influenciam um maior espalhamento da dor. A organização hodológica do núcleo espinal do trigêmeo e mecanismos fisiológicos de integração neural podem explicar de maneira satisfatória várias características da dor referida. Além disso, observamos que a resolução espacial na localização da dor é maior que a resolução espacial da localização de outros estímulos somestésicos nos elementos dentários. / The majority of patients who suffer from toothache report referred pain to other sites in the head and neck. Thus, the aim of this study was to investigate the clinical and psychophysical characteristics of referred pain in the orofacial region and how factors such as intensity, duration and nature of odontogenic pain might modulate them. We employed psychophysical and clinical methods to correlate pain perception with the anatomy and physiology of the trigeminal system. Sixty patients reporting primary toothache were investigated as to the clinical and psychophysical aspects of their pains symptoms and signals (intensity, duration, location and state of the pulp inflammatory process). Pain intensity and state of irreversible pulp inflammation were found to significantly affect facilitate the incidence of referred pain and its spread across vertical laminations. Considering these results, we proposed a physiological model based on both neuronal integration (spatial and temporal summation) and the topographic organization of the trigeminal system, which is able to explain the observed characteristics of referred dental pain.

No description available.

A maioria dos pacientes que têm dor de origem dentária pulpar ou periapical tem dor referida, e algumas características da dor parecem influenciar este fenômeno. Por meio do preenchimento de fichas clínicas, com informações sobre as características da dor, investigamos, em 60 voluntários, a distribuição topográfica de áreas de dor referida de origem dentária. Por meio de métodos psicofísicos, comparamos a resolução espacial da dor com a resolução espacial de outras modalidades somestésicas (mecânica e térmica). Nossos resultados indicam que a intensidade da dor favorece o fenômeno da dor referida e interfere na sua dispersão topográfica. Dentes algógenos com polpa viva influenciam um maior espalhamento da dor. A organização hodológica do núcleo espinal do trigêmeo e mecanismos fisiológicos de integração neural podem explicar de maneira satisfatória várias características da dor referida. Além disso, observamos que a resolução espacial na localização da dor é maior que a resolução espacial da localização de outros estímulos somestésicos nos elementos dentários. / The majority of patients who suffer from toothache report referred pain to other sites in the head and neck. Thus, the aim of this study was to investigate the clinical and psychophysical characteristics of referred pain in the orofacial region and how factors such as intensity, duration and nature of odontogenic pain might modulate them. We employed psychophysical and clinical methods to correlate pain perception with the anatomy and physiology of the trigeminal system. Sixty patients reporting primary toothache were investigated as to the clinical and psychophysical aspects of their pains symptoms and signals (intensity, duration, location and state of the pulp inflammatory process). Pain intensity and state of irreversible pulp inflammation were found to significantly affect facilitate the incidence of referred pain and its spread across vertical laminations. Considering these results, we proposed a physiological model based on both neuronal integration (spatial and temporal summation) and the topographic organization of the trigeminal system, which is able to explain the observed characteristics of referred dental pain.

Hintergrund: Der Geruchssinn spielt eine wichtige Rolle in unserem täglichen Leben, während sein Fehlen erhebliche Auswirkungen auf das Leben von Menschen mit Geruchsstörungen hat, einschließlich Veränderungen in ihrer geistigen, sozialen und körperlichen Gesundheit. Der Verlust des Geruchssinns kann eine Vorstufe zu schweren neurodegenerativen Erkrankungen wie Parkinson und Alzheimer sein, und kann mit depressiven Symptomen einhergehen. Daher sollten Menschen mit Riechverlust adäquat untersucht und behandelt werden. In den drei zu einer Arbeit zusammengefassten Veröffentlichungen wurde die MRT zur Untersuchung der Riechfunktion und ihrer Plastizität eingesetzt, vor allem bei Patienten mit Riechstörungen. Publikation 1 befasste sich mit der Verbesserung bestehender Methoden zur Bewertung des Volumens des Bulbus olfactorius (OB) hinsichtlich der strukturellen Bewertung der Riechfunktion. Publikation 2 befasste sich mit der funktionellen Plastizität des olfaktorischen Systems bei Patienten mit angeborener und erworbener Anosmie, wenn der olfaktorische Input fehlt. Publikation 3 befasste sich mit der Plastizität des chemosensorischen Systems am Beispiel der gewohnheitsmäßigen Exposition zu trigeminalen Gerüchen. Methoden: In Publikation 1 wurden 52 Probanden einer 3-T-MRT Untersuchung des Gehirns unterzogen. Alle Probanden wurden mit der 'Sniffin' Sticks'-Testbatterie auf ihre orthonasale Riechfunktion hin getestet. Mit Hilfe der AMIRA®-Software berechneten zwei geschulte Beobachter das OB-Volumen mit einem manuellen Segmentierungsverfahren, der planimetrischen manuellen Konturierung (PMC) (Fläche in mm3). Mit ITK-SNAP®-Software verwendeten die gleichen Beobachter die neue Methode 'box-frame' zur Berechnung des OB-Volumens. Zunächst wurde die Anzahl der Schichten (Länge) mit deutlicher Erkennbarkeit des OB notiert. Bei der Box-Methode wurde angenommen, dass Höhe und Breite der Markierungen in einem Winkel von 90° zueinander stehen. Das Volumen wurde als Vielfaches von L x B x H (Scheibendicke in mm3) berechnet. Bei divergenten Befunden wurde ein dritter Beobachter herangezogen, und die zwei am nächsten liegenden Volumina mit weniger als 10 % Unterschied zur weiteren Betrachtung ausgewählt. In Publikation 2 wurden 40 Probanden mit 3-T-fMRT untersucht. Davon waren 18 gesunde Probanden, 14 waren Probanden mit kongenitaler Anosmie und 8 hatten eine idiopathische Anosmie. Den Probanden wurden 36 Wörter mit starker olfaktorischer Assoziation (OW) und 36 Kontrollwörter mit geringer oder keiner olfaktorischen Assoziation (CW) präsentiert. Die Teilnehmer wurden angewiesen, die Anweisungen und Wörter zu lesen. Vor den Wortblöcken wurden die Teilnehmer darauf hingewiesen, sich auf die olfaktorischen Aspekte der angezeigten Wörter zu konzentrieren, um eine Erwartung für im Folgenden gezeigten Wörter zu wecken und um die OW- von den CW-Blöcken klar zu trennen. Geruchsbezogene semantische Unterschiede wurden als Kriterium für die Unterscheidung zwischen den Aktivierungen gewählt. Wir verglichen vor allem Aktivierungsphasen, in denen OW erwartet wurden mit denjenigen, in denen OW gelesen wurden. In Publikation 3 nahmen 40 gesunde Probanden an einer fMRT-Untersuchung teil. Ein Teil der Probanden kaute regelmäßig Kaugummi mit Minzegeschmack (GC, n = 20), ein anderer Teil verwendete nie bzw. sehr selten Kaugummi oder andere Lebensmittel mit Minzgerüchen, z.B. Pfefferminztee (N'GC, n = 20). Mit Hilfe eines computergesteuerten Olfaktometers wurden den Probanden in vier separaten Sitzungen zwei „trigeminale Gerüche“ (Pfefferminze und Minze) und zwei „olfaktorische Gerüche“ (Kirsche und Erdbeere) verabreicht. Nach jeder Sitzung bewerteten die Probanden die Intensität und die Angenehmheit der angebotenen Gerüche. Ergebnisse: In Publikation 1 berechneten wir die OB-Volumina mit beiden Techniken und fanden vergleichbare Ergebnisse. Für die von beiden Beobachtern berechneten Volumina wurde eine hohe Korrelation festgestellt. Für die manuelle Segmentierung betrug Cronbachs α 0,91 bzw. 0,93 für das rechte bzw. linke OB-Volumen, während für die Box-Frame-Methode α 0,94 bzw. 0,90 für das rechte bzw. linke OB-Volumen betrug. In Publikation 2 zeigten die Teilnehmer mit idiopathischer und congenitaler Anosmie während der Erwartung der OW eine stärkere Aktivierung im posterioren OFC, die sich bis zur rechten Insula, dem Caudatum und dem fronto-medialen OFC erstreckte. Während des Lesens der OW zeigten Teilnehmer mit congenitaler Anosmie eine stärkere Aktivierung im posterioren OFC, die bis zur Insula reichte. In Publikation 3 zeigte die GC-Gruppe eine höhere trigeminale Empfindlichkeit im Vergleich zur N'GC-Gruppe. Olfaktorische Gerüche aktivierten den bilateralen insulären Kortex und die Amygdala. Neben den olfaktorischen Bereichen (Amygdala, insulärer Kortex) führten trigeminale Gerüche auch zu Aktivierungen im rechten Thalamus und der rechten Substantia nigra. In der GC-Gruppe führten olfaktorische Gerüche zu einer stärkeren bilateralen Aktivierung des insularen Kortex als in der N‘GC-Gruppe, während für trigeminale Gerüche keine derartigen Unterschiede beobachtet wurden. GC-Probanden schienen auf trigeminale chemosensorische Reize empfindlicher zu reagieren. Schlussfolgerungen: Mit der Veröffentlichung 1 konnten wir eine neue zuverlässige Methode vorstellen, die plastische Veränderungen auf der Ebene des OB auf effiziente Weise messbar macht. Die Methode ist zeitsparend und erfordert nur einen geringen technologischen Aufwand, was in die klinische Routine bedeutsam ist. Damit können strukturelle plastische Veränderungen des zentralnervösen Riechsystems zu diagnostischen Zwecken effektiv genutzt werden. In Publikation 2 fanden wir funktionelle Plastizität bei Patienten mit angeborener und erworbener Anosmie. Dieser Ansatz zeigte eine Aktivierung in den sekundären Geruchsregionen wie dem posterioren OFC, die sich bei Menschen mit angeborener Anosmie im Vergleich zu Riechgesunden bis zur Insula ausdehnte. Diese Aktivität ist am ehesten im Zusammenhang mit multisensorischer Integration zu sehen, was wiederum auf kompensatorische Mechanismus für die Verarbeitung semantischer Geruchsinformationen bei fehlendem Riechvermögen schließen lässt. In Publikation 3 untersuchten wir die Plastizität des chemosensorischen Systems bei gewohnheitsmäßiger Exposition zu trigeminalen Gerüchen. Gegenüber selektiv olfaktorischen Aktivierungen gibt es Überlappungen aber auch deutliche Unterschiede in der Peripherie und im ZNS, wie trigeminale Gerüche verarbeitet werden. Erwartungsgemäß schienen Teilnehmer mit habituellem Minzgebrauch empfindlicher auf trigeminale chemosensorische Reize zu reagieren. Dies führte jedoch nicht zu Unterschieden in der zentralnervösen Aktivierung für trigeminale Reize. Vielmehr erschienen trigeminale Gerüche für die Gruppe mit geringem Minzkonsum bedeutungsvoller und erregender. In der Summe zeigen die Arbeiten, dass das chemosensorische System außerordentlich plastisch ist, auf stuktureller und funktioneller Ebene und wir uns ständig an unsere Umwelt anpassen.:List of Abbreviations 1 List of figures 1 List of Tables 3 Introduction 4 Olfactory system 4 Olfactory dysfunction 5 Anatomy of olfactory system 6 Chemosensory assessment 8 Psychophysical olfactory tests 8 Psychophysical Trigeminal tests 9 Electrophysiological tests - olfactory event related potentials (OERP) 10 Functional magnetic resonance imaging (fMRI) 10 Publication 1: Assessment of structural plasticity by measuring OB volume 11 Publication 2: Assessing functional plasticity using bottom- up and top- down olfactory processing 12 Publication 3: Assessing plasticity of chemosensory system 12 Methods 13 Method 1 13 Publication 1- A novel technique for olfactory bulb measurements 13 Method 2 18 Publication 3- Habitual Exposure to Trigeminal Stimuli and Its Effects on the processing of Chemosensory Stimuli 18 Contributions in publications 20 Publication 1: 20 Publication 2: 20 Publication 3: 20 Abstract of publication 1 21 Publication 2 (Second study): Neural processing of olfactory‑related words in subjects with congenital and acquired olfactory dysfunction 31 Abstract of publication 2 31 Publication 3 (Third study) Habitual Exposure to Trigeminal Stimuli and Its Effects on the processing of Chemosensory Stimuli 40 Abstract of publication 3 40 Discussion and Outlook 49 Summary in German 55 Hintergrund 55 Methoden 55 Ergebnisse 56 Schlussfolgerungen 56 Summary in English 58 Background 58 Hypothesis 58 Methods 59 Results 59 Conclusions 60 References 61 Curriculum vitae 80 List of scientific publications 82 Anlage 1 84 Anlage 2 85

L’opossum nait dans un état très immature, mais rampe avec ses membres antérieurs (MA) de l’orifice urogénital de la mère à une tétine, où il s’attache pour poursuivre son développement. Des informations sensorielles sont nécessaires pour guider le nouveau-né vers une tétine et déclencher son attachement. Des expériences précédentes ont montré que le système du trijumeau, dont dépend l’innervation somesthésique du museau, influence les mouvements précoces des MA. Le présent projet vise à déterminer si les mécanorécepteurs faciaux sont fonctionnels et exercent une influence sur les MA. On s’intéresse particulièrement aux cellules de Merkel, un mécanorécepteur épidermique innervé par des fibres à adaptation lente de type I (SA I). Ces cellules ont été localisées sur le pourtour du museau de l’opossum nouveau-né en utilisant un traceur cellulaire, l’AM1-43. Nous avons analysé les réponses musculaires des MA consécutives à l’application de forces calibrées au museau sur des préparations in vitro. Ces réponses sont bilatérales et simultanées, très variables, et leur intensité augmente avec la force de la stimulation. Lors de stimulations répétitives pendant 60 min, les réponses diminuent avec le temps. Le retrait de la peau faciale abolit presque ces réponses. De plus, l’application d’un antagoniste des récepteurs métabotropiques du glutamate, qui affecte l’activité des fibres SA I, ou d’un antagoniste des récepteurs purinergiques les diminue fortement, suggérant une participation des cellules de Merkel. Ces résultats soutiennent que le sens du toucher facial relayé par le système du trijumeau est fonctionnel chez l’opossum nouveau-né et qu’il pourrait influencer les mouvements des MA. / The opossum, Monodelphis domestica, is born very immature but crawls, unaided, with its forelimbs (FL) from the mother's birth canal to a nipple where it attaches to pursue its development. Sensory clues are needed to guide the newborn to the nipple and trigger its attachment to it. We postulated that the trigeminal system, responsible for sensory innervation of the face, is involved. Indeed, light pressure applied on the snout evokes FL movements in vivo, low intensity electrical stimulation of the trigeminal ganglion induces motor responses of the FL in vitro, and trigeminal fibers is distributed in the facial dermis and basal epidermis of the newborn. Also, slowly adapting mechanosensory receptors Merkel cells (AM1-43 positive) are present in the face epidermis. To determine if Merkel cells exert an influence on locomotion of newborn opossums, we analyzed the FL muscles responses following application of calibrated forces on the snout in in vitro preparations. Pressure applied to the face induced bilateral and simultaneous FL motor responses, which intensity is proportional to stimulation force. Following consecutive stimulations during 60 min, the responses tended to decrease. Removing the facial skin nearly abolished the responses. Bath applications of the glutamate metabotropic receptor antagonist YM298198, and of the purinergic receptors (P2) antagonist PPADS, decreased the muscles responses. These results support that touch sensitivity of the snout relayed by the trigeminal system is functional in newborn opossums and may influence FL movement, possibly contributing to guiding the animal to the nipple.

CONTEXTE: La maladie de Parkinson idiopathique (MPI), la démence à corps de Lewy (DCL) et la démence parkinsonienne (DP) sont des synucléinopathies. La dysfonction olfactive est reconnue comme étant une caractéristique principale de ces maladies. L'objectif de ce travail était d'évaluer et de comparer les seuils de détection olfactifs dans ces trois synucléinopathies (MPI, DP, DCL) chez des sujets âgés de plus de 65ans. Dans cette optique, trois études ont été menées utilisant des substances odorantes stimulant variablement les systèmes trigéminal et olfactif.MÉTHODES: les tests de détection des seuils olfactifs ont été réalisés chez (1) 89 patients ayant une MPI versus témoins sains, (2) 17 PD versus MPI et (3) 20 DCL versus PD versus témoins sains appariés, en utilisant l'alcool phényléthylique, le n-butanol et la pyridine comme stimuli. Les seuils de détection de ces 3 odorants ont été évalués à l'aide d'une série de dilution de facteur 2 et une procédure ascendante de choix forcé.Les données ont été analysées en utilisant des tests de Mann-Whitney-Wilcoxon ou Kruskal-Wallis, la corrélation de Spearman et des analyses de covariance. Des analyses discriminantes ont également été réalisées.RÉSULTATS: (1) Les seuils de détection olfactifs sont capables de discriminer les patients MPI des témoins sains et les patients ayant une MPI bénigne de ceux avec autonomie déficiente. De plus, nous avons trouvé une subtile interaction entre les systèmes olfacto-trigeminal.(2) Nos résultats mettent en évidence, une absence de différence significative des seuils de détection des odorants entre MPI et PD appariés.(3) Nous avons constaté des différences significatives des seuils olfactifs entre patients ayant une DCL, une DP et témoins sains (p <0,001), avec une altération majeure de la sensibilité olfactive chez les patients atteints de DCL par rapport à ceux ayant une DP.Au travers des 3 études, une corrélation significative a été trouvée entre les seuils de détection des trois odorants.CONCLUSION: Ce travail souligne que la DCL peut être distinguée de la DP, la DP des sujets sains et la MPI des sujets sains en évaluant les seuils de détection des trois odorants. Cependant, l’absence de différence significative entre les seuils de détection olfactifs entre les MPI et DP soulève des doutes sur l'importance des tests de seuils de détection olfactive dans le suivi cognitif dans la MPI. D'autres recherches sur le dysfonctionnement olfactif dans les synucléinopathies sont nécessaires pour conforter nos résultats.MOTS CLÉS: Principales synucléinopathies (maladie Parkinson idiopathique, Démence parkinsonienne, Démence à corps de Lewy); seuils de détection des odorants; interactions des systèmes olfacto-trigéminal ; diagnostics positif et différentiel. / Idiopathic Parkinson disease (IPD), Dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD) are synucleinopathies. Olfactory impairment is recognized as a characteristic feature of some synucleinopathies. The aim of this study was to assess and compare olfactory detection thresholds in these three synucleinopathies (IPD, PDD and DLB). For that purpose three studies were conducted: (1) Elderly with IPD matched to healthy controls, (2) IPD versus PPD and (3) between DLB, PDD and healthy controls using odor stimuli that variably trigger nasal trigeminal and olfactory systems.METHODS: Olfactory thresholds tests were performed in 89 IPD patients aged over 65 compared to paired matched healthy controls, in 17 IPD versus and matched PDD patients and in 20 LDB patients versus PDD patients versus matched healthy controls, using Phenyl-ethyl alcohol, n-Butanol and Pyridine as stimuli. Detection thresholds for these 3 odorants were assessed using an ascending staircase factor-2 odor dilutions series and a binary forced-choice procedure. Participants were priory evaluated by experimented physicians.Data were analyzed using Mann-Whitney-Wilcoxon or Kruskal-Wallis tests, Spearman correlation and covariance analyses. Discriminant analyses were also carried out to predict and classify the three participants’ groups in the third study.RESULTS: (1) Olfactory detection thresholds are able to discriminate elderly IPD from healthy controls, with a fair detection thresholds performance for pyridine compared to the two other odorants; and the ability to distinguish benign IPD patients with good autonomy from those with impaired autonomy (malign IPD). Moreover, we found subtle olfacto-trigeminal systems interaction.(2) Our results highlight no significant difference on odor detection threshold between elderly IPD compared with matched PDD patients.(3) We found significant odor thresholds differences between LBD patients, PDD patients and healthy controls (all p-values < 0.001), with also a significant poor sense of smell in DLB patients compared to moderate PDD patients. A plain differentiation between the three groups was confirmed by standardized canonical discriminant analyses.Through the 3 studies, a significant correlation was found between the odor detection thresholds.CONCLUSION: This work highlights that DLB can be distinguished from PDD, PDD from healthy controls and IPD from healthy controls by assessing odors (PEA, n-butanol, pyridine) detection thresholds. However, the lack of difference between olfactory thresholds between IPD and PDD raises doubts on the importance of olfactory thresholds tests in the cognitive follow-up of patients with IPD.Further investigations of olfactory dysfunction in patients with synucleinopathies are needed to confirm our results.KEYWORDS: idiopathic Parkinson disease; Parkinson's disease dementia ; Dementia with Lewy bodies; odor detection thresholds; chemonasal trigeminal and olfactory systems interactions; clinical diagnosis.

A deeper understanding of both movement control and the effects of nociceptor inputs on our motor systems is critical for proper clinical diagnosis of musculo-skeletal dysfunctions and for development of novel rehabilitation schemes. In the jaw system, masticatory movements are produced by a central pattern generator (CPG) located in the brainstem. Considerable efforts have been made in deciphering this neuronal network. The present thesis contributes towards an increasingly detailed understanding of its essential elements, and presents a hypothesis of how deep somatic pain (i.e. muscle pain) may be evoked and interferes with the masticatory CPG circuitry. In Paper I, the expression of c-Fos-like protein was used as a molecular marker to visualize brainstem neurons that were active during induced fictive mastication in the anesthetized and paralyzed rabbit. Our findings provide a previously lacking detailed record of the neuronal populations that form the masticatory motor pattern. Certain cells were located in brainstem areas previously suggested to be involved in the masticatory CPG. However, it was a new finding that neurons in the dorsal part of the trigeminal main sensory nucleus (NVsnpr-d) may belong to this circuitry. Paper II focused on the discovered neurons in NVsnpr in an in vitro slice preparation from young rats.  Intracellular recordings allowed us to define two cell types based on their response to depolarizing current. Microstimulation applied to the trigeminal motor nucleus, its reticular border, the parvocellular reticular formation and the nucleus reticularis pontis caudalis, elicited postsynaptic potentials in 81% of the neurons tested. Responses obtained were predominately excitatory and sensitive to gluta-matergic antagonists DNQX or/and APV. Some inhibitory and biphasic responses were also evoked. Bicuculline methiodide or strychnine blocked the IPSPs indicating that they were mediated by GABAA or glycinergic receptors. About one third of the stimulations activated both types of neurons antidromically. Neurons in NVsnpr-d seem to gather all the conditions that can theoretically account for a role in masticatory rhythm generation. In Paper III, the masticatory model system was used to investigate the possible role of muscle spindle primary afferents in development of persistent musculoskeletal pain. Following intramuscular acidic (pH 4.0) saline injections of rat masseter muscles, in vitro whole cell recordings were done from jaw closing muscle spindle somata located in the trigeminal mesencephalic nucleus (NVmes). Compared to control neurons, the somata of afferents exposed to acid had more hyperpolarized membrane potentials, more hyperpolarized thresholds for firing, high frequency membrane oscillations and ectopic bursting of action potentials. These changes in membrane properties lasted for up to 35 days. Within the same time frame experi-mental animals showed hypersensitivity to touch on the skin covering the injected muscle. Similar saline injections also resulted in a significant increase of activity dependent c-Fos expression in NVmes neurons compared to controls. Immuno-fluorescence and lectin binding studies indicated that small-caliber muscle afferents containing known nociceptor markers (CGRP, SP, P2X3, TRPV1 and IB4) and expressing glutamate receptors are found close to the annulo-spiral endings of the NVmes afferents. Combined, our new observations support the hypothesis that excessive release of glutamate, within muscle spindles due to ectopically evoked antidromic action potentials, could lead to development of persistent musculoskeletal pain by activation and/ or sensitization of adjacent muscle afferent nociceptors.

The ability to perceive the Earth's magnetic field has been demonstrated in a variety of animals, including representatives of all five classes of vertebrates. The physiological mechanisms underlying magnetic field sensation, however, remain largely unknown. Behavioral, physiological, neuroethological studies and studies using early response genes as neuronal activation markers indicated that a major role in the perception and processing of magnetic information play trigeminal, vestibular and visual systems. Subsequently, magnetic information seem to be integrated with multimodal sensory and motor information within the hippocampal-entorhinal system. In the majority of studies, however, birds have been used as model organisms. In this work I analyzed the neural substrate of magnetic compass orientation in the mouse strain C57BL/6J using markers c-Fos and Egr1. I found that all the aforementioned systems contain neurons responsive to the experimental magnetic fields. This finding demonstrates a complex processing of the magnetic information at level of the central nervous system.

Os objetivos do presente trabalho foram: 1) analisar a distribuição das fibras nervosas autonômicas na articulação temporomandibular (ATM) do rato, através da detecção de tirosina hidroxilase (TH), neuropeptídeo Y (NPY) e peptídeo intestinal vasoativo (VIP); 2) realizar um estudo topográfico ultra-estrutural das fibras e terminações nervosas autonômicas na ATM do rato; 3) determinar o padrão de ativação neuronal no complexo nuclear trigeminal e, em centros nervosos moduladores da dor, durante a vigência de monoartrite no complexo articular temporomandibular (CATM) do rato. Para o primeiro propósito o método imunoistoquímico, para a detecção simultânea de TH, NPY e VIP, foi executado em ATMs que apresentavam as seguintes condições: inervação intacta ou desprovida de inervação simpática e/ou parassimpática. Para o segundo propósito aliamos o tratamento prévio com 5-hidroxidopamina, para evidenciação de terminações nervosas simpáticas, com a remoção cirúrgica do gânglio ótico, para a visualização das fibras e terminações nervosas parassimpáticas em degeneração, em seguida analisamos as ATMs ao microscópio eletrônico de transmissão. O terceiro propósito foi obtido induzindo-se monoartrite (fase aguda, crônica e crônica ativa) no CATM e, verificando a expressão de Fos, um marcador de ativação neuronal, no complexo nuclear sensorial trigeminal e nos principais centros nervosos moduladores da dor, situados no tronco encefálico (substância cinzenta periaqueductal- PAG; área rostral ventromedial da medula oblonga- RVM; locus coeruleus- LC; área caudal ventrolateral da medula oblonga- CVLM; núcleo do trato solitário- NTS e; núcleo reticular ventral-NRV). Verificamos que as ATMs desprovidas de inervação simpática apresentam exclusivamente uma pequena quantidade de fibras nervosas VIP-IR, ao passo que aquelas desprovidas de inervação parassimpática mostram uma grande quantidade de fibras nervosas TH/NPY-IR e TH/NPY/VIP-IR. As fibras e terminações nervosas autonômicas foram observadas em vasos sanguíneos ou isoladas no tecido conjuntivo, especialmente na membrana sinovial. No que se refere à expressão de Fos, constatamos que o subnúcleo caudal do núcleo do tracto espinal do nervo trigêmeo (Sp5C) e a PAG apresentaram um aumento bilateral significante na expressão de Fos durante todas as fases da monoartrite induzida no CATM. Todavia, RVM, LC, CVLM, NTS apresentaram uma quantidade de neurônios Fos-IR significativamente aumentada, de ambos os lados, apenas quando o CATM estava sob vigência de monoartrite na fase aguda e crônica ativa. Concluímos que: 1) a ATM mostra-se densamente inervada por fibras nervosas simpáticas (TH/NPY-IR e TH/NPY/VIP-IR) e, por uma discreta quantidade de fibras nervosas parassimpáticas (VIP-IR), ambas predominantemente associadas com vasos sanguíneos; 2) o Sp5C e a PAG, mostra-se intensamente ativados em todas as fases da monoartrite no CATM, ao passo que a maioria dos centros nervosos moduladores da dor apresentam uma quantidade aumentada de neurônios imunoarreativos ao marcador de ativação neuronal, Fos, apenas durante as fases aguda e crônica ativa dessa monoartrite. / The goals of the present study were: 1) to analyse the distribution of autonomic nerve fibers in the rat temporomandibular joint (TMJ) under normal conditions using immunofluorescence method to detect tirosyne hydroxylase (TH), neuropetide Y (NPY) and vasoactive intestinal polypeptide (VIP); 2) to verify the detailed distribution of autonomic nerve fibers in the rat temporomandibular joint by transmission electron microscopy; 3) to determine the neuronal activation pattern in the trigeminal system and in the pain modulation centers during monoarthritis induced in the rat temporomandibular joint complex (TMJC). For the first purpose, histologic sections from TMJs with intact innervation or with surgical sympatectomy and/or parasympathectomy were submitted to simultaneous detection of TH, NPY and VIP. For the second purpose, 5-hydroxidopamine treatment to detect sympathetic nerve endings was combined with surgical parasympatectomy of the otic ganglion to detect degenerated parasympathetic nerve endings in the rat TMJC, by transmission electron microscopy. For the last purpose, monoarthritis (acute, chronic and chronic-active phases) was induced in the TMJC and histologic sections from the brain stem were submitted to immunodetection of Fos protein in the trigeminal system and in the pain modulation centers (periqueductal gray matter - PAG; rostroventromedial medulla - RVM; locus coeruleus- LC; caudal ventrolateral medulla- CVLM; nucleus of the solitary tract - NTS; ventral reticular nucleus - VRN). The most important results demonstrated that the TMJC showed a discrete parasympathetic innervation (VIP-IR), while the sympathetic innervation was dense and characterized by TH-/NPY-/VIP-IR or TH-/NPY-IR nerve fibers. Autonomic nerve fibers were mainly noted associated to blood vessels and occasionally disperse in the synovial membrane. Fos-IR neurons showed significant bilateral increase in the spinal trigeminal caudal subnucleus and PAG during arthritis evolution. On the other hand, RVM, LC, CVLM and NTS only showed significant increase of Fos-IR neurons during the acute and chronic-active phases of monoarthritis. The main conclusions were: 1) the TMJC shows a dense sympathetic innervation (TH/NPY-IR or TH-/NPY-/VIP-IR) and discrete parasympathetic innervation (VIP-IR), both associated mainly to blood vessels; 2) most modulation pain centers are activated principally during acute and chronic-active arthritis, while the spinal trigeminal caudal subnucleus and PAG showed continuous activation during all phases of arthritis.