Chez les mamifères terrestres, l’échantillonnage des odeurs (flairage) est inextricablement lié à la respiration. Le flairage contraint à la fois le décours temporel et l’intensité de l’input olfactif. Or le flaireage est un acte dynamique, il peut varier aussi bien en fréquence qu’en débit. Dans une 1ère partie de mon travail de thèse, nous avoins souhaité caractériser l’impact des variations de fréquence et de débit respiratiore sur l’activité du bulbe olfactif. Pour cela, nous avons mis au point une méthode de double trachéotomie chez le rat anesthésié nous permettant de contrôler précisément les flux d’air ans la cavité nasale. En paralèlle, nous avons enregistrer l’acitivité unitaire et de réseau du bulbe olfactif. Nous montrons que les variations de flairage modulent la représentation neuronale bulbaire des odeurs en modifiant à la fois l’activité de décharge des cellules principales et l’occurence des oscillaations du potentiel de champ local. Dans une 2e partie de ma thèse, nous avons souhaitécomprendre quel pouvait être le rôle du flairage chez un animal qui se comporte. Nous avons posé l’hypothèse qu’un animal pouvait adapter sa façon de flaireer en fonction de la qualité des molécules odorantes. Pour tester cette hypothèse, nous avons mis au point un système d’enregeistrement non invasif de la respiration couplé à une tâche de discrimination olfactive chez le rat. Nous montrons non seulement que les animaux peuvent adapter leur flairage en fonction des molécules odorantes masi également en focntion du contexte dans lequel l’odeur est présentée. L’ensemble de ces résultats s’intègre donc dans la problématique plus générale de l’intégration sensori-motrice. / In terrestrial mammals, an inextricable link between olfaction and respiration exists due to the periodic sampling of odorant molecules by inhalation. The features of sniffing (or breathing) constrain both the timing and the intensity of the input to the olfactory structures. But rather than being fixed, sniffing in the bahavingrodent is highly dynamic and varies both in frequency and flow rate. During the firs stage of my PhD, I asked to what extent sniffing parameters (frequency and flow rate) variations could affect the olfactory bulb activity. To address this question, I developped a double tracheotomy protocol in anesthetized rats to precisely control and modify the nasal airflow. In parallel, I recorded oldfactory bulbactivities, single-unit activity and local field potentials. We showed that, at the olfactory bulb level, the neutral representation of an odor is highly modified by sampling variations. In fact both the mitral/tufted cell discharge patterns and local field potentials oscilliations were affected by sniffing variations. In the second stage, we wanted to understand the role of sniffing variations in behaving animals. We hypothesized tha t an animal could adapt its sniffing strategy relative to the quality of the odorant molecules. To test this hypothesis, we developped a tool to record sniffing in a non invasive way, and combined it to an olfactory discrimination task in the rat. We showed that animals not only adapted their sniffing relative to the odorant quality but also to the odorant context. Taken together, these results fit into the broader context of sensory-motor integration.

Objective: Decrease of olfactory function in Parkinson's disease (PD) is a well-investigated fact. Studies indicate that pharmacological treatment of PD fails to restore olfactory function in PD patients. The aim of this investigation was whether patients with PD would benefit from “training” with odors in terms of an improvement of their general olfactory function. It has been hypothesized that olfactory training should produce both an improved sensitivity towards the odors used in the training process and an overall increase of olfactory function. Methods: We recruited 70 subjects with PD and olfactory loss into this single-center, prospective, controlled non-blinded study. Thirty-five patients were assigned to the olfactory training group and 35 subjects to the control group (no training). Olfactory training was performed over a period of 12 weeks while patients exposed themselves twice daily to four odors (phenyl ethyl alcohol: rose, eucalyptol: eucalyptus, citronellal: lemon, and eugenol: cloves). Olfactory testing was performed before and after training using the “Sniffin' Sticks” (thresholds for phenyl ethyl alcohol, tests for odor discrimination, and odor identification) in addition to threshold tests for the odors used in the training process. Results: Compared to baseline, trained PD patients experienced a significant increase in their olfactory function, which was observed for the Sniffin' Sticks test score and for thresholds for the odors used in the training process. Olfactory function was unchanged in PD patients who did not perform olfactory training. Conclusion: The present results indicate that olfactory training may increase olfactory sensitivity in PD patients.

Les modalités sensorielles ont un rôle essentiel dans la collecte des informations en provenance de l’environnement. En olfaction, l’échantillonnage actif des odeurs se fait via le flairage chez le rat (2-10 Hz). Chez l’animal qui se comporte, le flairage est un acte très dynamique, il varie en particulier en fréquence et en débit. Le flairage peut être modulé par des facteurs liés au stimulus, comme les propriétés physico-chimiques des odeurs ou leur concentration, ou par des facteurs plus « internes » comme l’attention, les émotions ou la motivation. Plusieurs auteurs ont également suggéré l’importance de la fréquence de flairage dans la performance. Dans une première partie de ma thèse, j’ai voulu caractériser l’impact d’un apprentissage olfactif sur la mise en place d’un pattern de flairage adapté à la discrimination. Pour cela, j’ai utilisé un système d’enregistrement de la respiration non invasif chez le rat (pléthysmographe) pendant que l’animal effectue une tâche de discrimination olfactive à double choix. Dans une seconde partie, j’ai cherché les corrélats neuronaux de l’acquisition de ce pattern de flairage en enregistrant simultanément l’activité respiratoire et les signaux neuronaux (potentiels de champ locaux) dans des aires olfactives, motrices et limbiques chez l’animal en comportement. J’ai cherché à caractériser les activités oscillatoires dans la bande bêta (15-30 Hz) et thêta (2-10 Hz). J’ai enfin discuté dans quelle mesure celles-ci pouvaient être reliées à l’apprentissage et/ou aux variations de l’activité respiratoire / Sensory modalities actively take part in collecting relevant information from the environment. In olfaction, active sampling amounts to sniffing in rodents (2-10 Hz). In behaving animals, sniffing is highly dynamic, notably in frequency and flow rate. Sniffing can be modulated by parameters related to the odorant stimulus, such as the physicochemical properties of the molecule or its concentration. It can also vary depending on “internal” parameters such as attention, emotions or motivation. Several studies highlighted the importance of the sniffing frequency in performance. First, I looked at the impact of olfactory learning on the acquisition of a specific sniffing pattern. For that purpose, I monitored sniffing activity in a non-invasive way, using a whole-body plethysmograph, on rats performing a two-alternative choice odor discrimination task. Second, I looked for neuronal correlates of the acquisition of such a sniffing pattern by simultaneously recording sniffing and neuronal activities (local field potentials) in olfactory, motor and limbic areas in behaving animals. I sought to characterize oscillatory activities in beta (15-30 Hz) and theta (2-10 Hz) ranges. I finally discussed to what extent they were related to learning and/or sniffing modulations

This project explores opportunities in designing hybrid digital/physical smell rehabilitation video games using no unique game peripherals. During a 13-week process, three major iterations were created and externally tested on a small user group. The first two iterations contained five simple minigames that served to explore different types of game concepts. For the final iteration, two minigames were fully developed, a slow- and fast-paced game. The main findings were that slow-paced better-facilitated smell training than fast-paced games; aesthetics increased the player’s focus on small training; not utilising unique game peripherals limited the design opportunities and implementation of smell mechanics.

Olfactory sensory decline has been associated with normal aging as well as neurodegenerative disorders, yet the underlying mechanisms are unclear. The overall aim of this dissertation was to investigate the fundamental molecular and cellular mechanisms associated with olfactory neurodegeneration. This investigation uses an integrative approach, combining proteomics and gene expression analyses with cellular and tissuelevel characterization. Using these approaches, two model systems were investigated: 1) normally aging C57BL/6 mice of ages 1.5-, 6- and 20-months; and 2) a mouse model of elevated endogenous oxidative stress-associated neurodegeneration, namely, the Harlequin mutant mouse. The first specific aim was to test the hypothesis that oxidative stress is associated with aging of the olfactory system. Using proteomics, I demonstrated that olfactory aging was accompanied primarily by increased oxidative stress-, mitochondrial metabolism- and synaptic/transport-associated changes. The second specific aim was to test the hypothesis that the olfactory system accumulates oxidative stress-mediated macromolecular damage over time, predisposing it to neurodegeneration. Two types of protein oxidation, namely, carbonylation and nitration, accumulated with aging in the olfactory system. Protein and cellular targets of oxidative stress-associated damage were identified using redox proteomics coupled with immunohistochemical localization. The third specific aim was to test the hypothesis that elevated oxidative stress in the olfactory system results in apoptosis/neurodegeneration. The Harlequin mutant mouse was critically selected and validated as a model for studies of oxidative stress-associated olfactory neurodegeneration at both the cellular and molecular levels. The Harlequin mouse had decreased levels and altered distribution of apoptosis inducing factor protein in mature olfactory sensory neurons, increased oxidative DNA damage and apoptosis in the olfactory epithelium, and pronounced cytoskeletal disorganization. The molecular studies confirmed and extended our cellular data and identified several significantly regulated genes associated with elevated oxidative stress and apoptosis. This novel study, by combining contemporary proteomics and genomics with cellular and tissue-level analyses, has provided a road map for understanding fundamental molecular mechanisms of olfactory degeneration.

De flesta forskare inom området är överens om att det finns kopplingar mellan luktsinnet och känslor. Däremot finns det mindre forskning och bevis kring hur människors inre tillstånd påverkar olfaktorisk perception, dvs. uppfattningen av dofter. Föreliggande studie hade avsikt att studera sambandet mellan sinnesstämning och uppskattning av behagliga dofter. Den aktuella sinnesstämningen mättes med hjälp av Mood Adjective Checklist (Sjöberg et.al., 1979), ett tillförlitligt och känsligt instrument. För att mäta doftuppskattning användes fem olika dofter på doftstickor. Dofterna valdes ut systematiskt, testades i förväg och bekräftades som behagliga. Resultaten kunde inte visa något signifikant samband mellan sinnesstämning och doftuppskattning (p = .612). Ingen predicerande effekt i sinnesstämning och i de olika dimensionerna av sinnesstämningen på doftuppskattning kunde påvisas (p varierar mellan .293 och .862). Resultaten kan ha påverkats av metodologiska brister och utformningen av dofttestningsinstrumentet som diskuterats.

ABSTRACT In humans, advanced malignancies are often targeted with broad-spectrum cytotoxic drugs that engender several detrimental side effects, in addition to their primary usage for eradicating cancerous cells. One of the lesser-researched of these effects, histological distortion of the olfactory system impedes a patient's ability to smell, perceive flavor, and ultimately may interfere with their nutritional intake and recovery from chemotherapy. Recent studies have indicated that cytotoxic drugs can damage gustatory epithelia immediately following administration (Mukherjee & Delay, 2011, 2013). We sought to observe the histological effects that cyclophosphamide (CYP), one of the oldest and most popular alkylating antineoplastic agents, may have on the murine main olfactory epithelium (MOE) and vomeronasal organ (VNO). We utilized two immunohistochemical antibodies to label cells in the olfactory epithelia: anti-Ki67, a marker strictly associated with cell proliferation; and, anti-Keratin 5, a marker for the cytoskeleton of horizontal basal cells. Twenty-eight C57BL/6 mice were administered a single intraperitoneal injection of CYP (75 mg/kg), while 20 control mice were administered saline, all at approximately seven weeks of age. Mice were euthanized at days one, two, six, 14, 30, and 45 post injection; subsequently, they were perfused with 4% paraformaldehyde, decalcified, cryoprotected, cryosectioned, and incubated with anti-Ki67 and anti-Keratin 5 antibodies, sequentially. Quantification results by fluorescent imaging of labeled sections revealed a significant decrease in the number of proliferative cells in the MOE and VNO of CYP-injected mice within the first 10 days post injection, followed by a compensatory period of increased cell proliferation through day 45 post injection, compared to saline-injected mice. Co-localization of horizontal basal cells and proliferative cells in the MOE and VNO of CYP-injected mice was significantly amplified at approximately 14 and 45 days post injection, respectively, compared to saline-injected mice. Our results suggest that administration of CYP can rapidly depress the populations of proliferative cells in the murine MOE and VNO; consequently, horizontal basal cells may afford restoration of the proliferative cell populations in the murine MOE and VNO, 14 to 45 days post injection, respectively.

Olfactory receptor neurons (ORNs) maintain the ability to regenerate. These neurons reside in the olfactory epithelium and project axons that connect to the olfactory bulbs. Despite the diffuse distribution of ORNs in the olfactory epithelium, they converge at discrete glomeruli in the olfactory bulb. In the P2 IRES tau-lacZ mouse, the P2 ORN subtype has been previously mapped to two glomeruli, using X-gal staining. To determine if age affects ORN regeneration, left olfactory nerve transections were performed on P2 mice from immature (five-weeks old) and mature (1 6-weeks old) groups. Following recovery, the olfactory bulbs were processed to observe ORN regeneration. A significant difference was seen in the number and mapping of full P2 glomeruli between lesioned and control olfactory bulbs, but not between the age groups. This suggests that age differences between the two groups in this study were not large enough to affect the regeneration of P2 ORNs.

Traumatic brain injury (TBI) is a serious health concern, causing cognitive, motor, and sensory deficits, including olfactory dysfunction. This dissertation explores the effects of TBI on synaptic plasticity within the olfactory system, seeking to define mechanisms guiding postinjury sensory reinnervation. Physical forces induced by TBI can axotomize olfactory receptor neurons (ORNs), which innervate olfactory bulb (OB). These axons regenerate OB projections after injury, a process involving growth through a complex extracellular matrix (ECM). As such, we investigated a potential molecular mechanism capable of modifying local OB ECM to support postinjury synaptogenesis. Since matrix metalloproteinases (MMPs) and their ECM substrates are recognized for TBI therapeutic potential, we explored the role of MMP9 and its substrate osteopontin (OPN) in promoting ORN reinnervation of the OB after mild fluid percussion injury (FPI). First, we confirmed that FPI deafferented the mouse OB. In Chapter 2, we showed concurrent activation of neuroglia, elevated spectrin proteolysis and reduction in ORN-specific olfactory marker protein (OMP). As OMP normalized during regeneration, growth associated protein-43kD (GAP-43) peaked, marking OB entry of ORN growth cones. Ultrastructural analysis revealed ongoing ORN axon shrinkage and degeneration, glial phagocytosis of cellular debris, and a reorganization of synaptic structure. To explore ECM role in mediating postinjury OB reinnervation, we defined the time course of MMP9 activity and several downstream targets. Chapter 3 reports biphasic MMP9 activity increase during acute/subacute degeneration, accompanied by robust generation of 48kD OPN cell signaling peptide. OPN receptor CD44 also increased during the acute/subacute interval, suggesting potential interaction of the two proteins. Finally, we utilized MMP9 knockout (MMP9KO) mice to confirm MMP9 role in OB synaptogenesis. In Chapter 4, MMP9KO reversed FPI-induced lysis of 49kD OPN and altered postinjury expression of ORN axon degeneration marker OMP. Additional ultrastructural analysis verified delayed recovery of OB synaptic features within the injured MMP9KO. Overall, we demonstrated that mild FPI elicits ORN axotomy to induce OB reactive synaptogenesis, and that MMP9 supports reinnervation by processing OPN for activation of local glia, cells which reorganize the ECM for synapse regeneration.

Introduction Advanced Kadish stage esthesioneuroblastoma requires more extensive resections and aggressive adjuvant therapy to obtain adequate disease-free control, which can lead to higher complication rates. We describe the case of a patient with Kadish D esthesioneuroblastoma who underwent multiple surgeries for infectious, neurologic, and wound complications, highlighting potential preventative and salvage techniques. Case Presentation A 61-year-old man who presented with a large left-sided esthesioneuroblastoma, extending into the orbit, frontal lobe, and parapharyngeal nodes. He underwent margin-free endoscopic-assisted craniofacial resection with adjuvant craniofacial and cervical radiotherapy and concomitant chemotherapy. He then returned with breakdown of his skull base reconstruction and subsequent frontal infections and ultimately received 10 surgical procedures with surgeries for infection-related issues including craniectomy and abscess evacuation. He also had surgeries for skull base reconstruction and CSF leak, repaired with vascularized and free autologous grafts and flaps, synthetic tissues, and CSF diversion. Discussion Extensive, high Kadish stage tumors necessitate radical surgical resection, radiation, and chemotherapy, which can lead to complications. Ultimately, there are several options available to surgeons, and although precautions should be taken whenever possible, risk of wound breakdown, leak, or infection should not preclude radical surgical resection and aggressive adjuvant therapies in the treatment of esthesioneuroblastoma.