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Dentists' Views and Practice of Sedation and General Anaesthesia in OntarioPatodia, Sangeeta 09 December 2013 (has links)
This study investigated Ontario dentists' views and use of sedation and general anaesthesia (GA) (n=1076; 37.9% response rate). A mixed mode format offered mailed and web survey options. Study participants were 69.7% male, 83.0% general practitioners, practicing 0.5-42 years (mean 20.6 years), with 40.6% from cities >500,000. 60.2% of respondents provided sedation. Dentists' underestimated patient interest in sedation/GA (66.8% vs. 43.9% not interested; 19.8% vs. 42.8% possibly interested; 13.4% vs. 12.4% definitely interested). Patients' preference for sedation/GA by service was also underestimated (p<0.001) except for extractions. Barriers to care were cost (72.2%) for providers; lack of training (38.2%) and patient demand (25.3%) for non-providers. Dentists reported use of sedation highest for extractions (1.5% deep sedation/GA-5.7% nitrous). Dentists' also overestimated patients' level of fear (somewhat afraid 19.95 vs. 9.8%; very afraid 10.6% vs. 2.0%; terrified 6.0% vs. 3.5%). This study confirms differences between dentists' use and estimation of patient demand for sedation/GA.
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Dentists' Views and Practice of Sedation and General Anaesthesia in OntarioPatodia, Sangeeta 09 December 2013 (has links)
This study investigated Ontario dentists' views and use of sedation and general anaesthesia (GA) (n=1076; 37.9% response rate). A mixed mode format offered mailed and web survey options. Study participants were 69.7% male, 83.0% general practitioners, practicing 0.5-42 years (mean 20.6 years), with 40.6% from cities >500,000. 60.2% of respondents provided sedation. Dentists' underestimated patient interest in sedation/GA (66.8% vs. 43.9% not interested; 19.8% vs. 42.8% possibly interested; 13.4% vs. 12.4% definitely interested). Patients' preference for sedation/GA by service was also underestimated (p<0.001) except for extractions. Barriers to care were cost (72.2%) for providers; lack of training (38.2%) and patient demand (25.3%) for non-providers. Dentists reported use of sedation highest for extractions (1.5% deep sedation/GA-5.7% nitrous). Dentists' also overestimated patients' level of fear (somewhat afraid 19.95 vs. 9.8%; very afraid 10.6% vs. 2.0%; terrified 6.0% vs. 3.5%). This study confirms differences between dentists' use and estimation of patient demand for sedation/GA.
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The Clinical Relevance of Paediatric Access Targets for Elective Dental Treatment Under General AnaesthesiaChung, Sonia 06 April 2010 (has links)
The purpose of this study was to evaluate the clinical relevance of access targets for elective dental general anaesthesia (GA) by assessing incremental changes in dental disease burden over wait times at SickKids. A retrospective review of dental records were completed for 378 children who were prioritized by their dental and medical status. A scale was developed to measure cumulative dental disease burden over time. Statistically significant correlations were identified between cumulative disease burden and wait times for priority IV (p = 0.004), the entire sample (p < 0.003), DOSDCADCA (p = 0.005), comorbid (p = 0.036), healthy (p = 0.0002), female (p = 0.014) and male (p = 0.008) groups. The mean cumulative disease burden was not different between matched healthy and cormorbid groups (p = 0.38). A trend of increasing dental disease burden for children with longer wait times for dental GA was found but not clinically significant.
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The Clinical Relevance of Paediatric Access Targets for Elective Dental Treatment Under General AnaesthesiaChung, Sonia 06 April 2010 (has links)
The purpose of this study was to evaluate the clinical relevance of access targets for elective dental general anaesthesia (GA) by assessing incremental changes in dental disease burden over wait times at SickKids. A retrospective review of dental records were completed for 378 children who were prioritized by their dental and medical status. A scale was developed to measure cumulative dental disease burden over time. Statistically significant correlations were identified between cumulative disease burden and wait times for priority IV (p = 0.004), the entire sample (p < 0.003), DOSDCADCA (p = 0.005), comorbid (p = 0.036), healthy (p = 0.0002), female (p = 0.014) and male (p = 0.008) groups. The mean cumulative disease burden was not different between matched healthy and cormorbid groups (p = 0.38). A trend of increasing dental disease burden for children with longer wait times for dental GA was found but not clinically significant.
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Predictors of difficult intubation in obstetric cohort of patients: an analysis of the prospective obstetric airway management registry (OBAMR) (substudy – R025/2018)Burger, Adrian 02 August 2021 (has links)
Abstract Background: Hypoxaemia during tracheal intubation in obstetrics remains a lifethreatening complication. This study aimed to identify common clinical preinduction predictors of difficult intubation. Methods: A retrospective analysis was performed of data pertaining to tracheal intubation in patients requiring general anaesthesia for caesarean delivery, with a gestational age from 20 weeks, and until 7 days post-delivery, obtained from an obstetric airway management registry (ObAMR) at the University of Cape Town. Data was entered anonymously into a secure UCT REDCap database. Data categories were: patient and pregnancy characteristics, airway characteristics, details of management, and operator experience. The primary aim of the study was to identify anatomical and physiological risk factors for hypoxaemia. The primary outcome was defined as arterial desaturation to < 90% during obstetric airway management. For this purpose, multivariable binary logistic regression was performed. Hypoxaemia was thus used as a composite indicator of anatomical and physiological difficulty. Results: Data was collected for 1095 general anaesthetics in the ObAMR. Overall, 143/1091 of patients (13.1%, 95%CI 11.1 to 15.4%) experienced peripheral oxygen saturation below 90%. Univariate analysis showed that 91/142 (64.1%) of patients who desaturated were obese (body mass index [BMI]> 30 kg/m2 ), compared with 347/915 (37.9%) who were obese and did not experience desaturation (p< .001). A receiver operating curve (ROC) was constructed post hoc, which showed a cut-point for BMI of 29.76, and a sensitivity of 0.66, and specificity 0.62 for the prediction of hypoxaemia. Desaturation occurred in 17.0% of patients with hypertensive disorders of pregnancy, versus 11.0 % without (p=0.005). Increasing Mallampati class was associated with an increased incidence of hypoxaemia. The incidence of hypoxaemia was 25.8% for interns, compared with 8.0 % for consultant anaesthesiologists (p=0.005). In the multivariate analysis of factors associated with hypoxaemia, body mass index (p< 0.001), room air saturation prior to preoxygenation (p=0.008), and the presence of airway oedema (p=0.027), were independently associated with hypoxaemia. Conclusions: In this study, both anatomical and physiological predictors of hypoxaemia were identified. Using this concept, a predictive tool could be developed to aid in the identification of a difficult airway in obstetrics. Simple interventions such as face mask ventilation and the use of high flow nasal oxygenation, could be introduced to protect the parturient from the consequences of life-threatening hypoxaemia.
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Pulmonary atelectasis : computed tomography findings in healthy Beagles under general anaesthesiaLe Roux, Christelle January 2016 (has links)
A large proportion of dogs undergoing computed tomography are anaesthetised and receive concurrent supplementary oxygen. Both factors promote the development of pulmonary atelectasis, which may mask or mimic lung pathology and compromise image quality, which is of concern to the radiologist. The aim of the study was firstly to determine whether significant atelectasis would develop using a commonly employed anaesthetic protocol in a typical hospital setting, especially where dogs may have been anaesthetised in lateral recumbency prior to scanning. Secondly, to determine whether a change in body position to sternal recumbency would be sufficient to resolve atelectasis.
Six healthy adult Beagles were anaesthetised in sternal recumbency and using a breath-hold technique, baseline helical transverse thoracic images were acquired. Dogs were then placed in either right or left lateral recumbency for 30 minutes, with scans performed at predetermined lung lobe locations and time intervals. Dogs were then repositioned in sternal recumbency for a further 20 minutes, with similar scans performed. The study was repeated two weeks later in the opposite lateral recumbency. Changes in Hounsfield units and cross-sectional area of all lung lobes were measured.
Lateral recumbency did not result in true atelectasis in healthy Beagles of normal body condition. Infrequently, patchy increased attenuation, which failed to resolve completely during sternal recumbency, was visualised in the left cranial lobe during left lateral recumbency. The degree of attenuation changes in healthy Beagles was minimal, and thus if dogs were anaesthetised in lateral recumbency prior to computed tomography, this should not preclude scanning. / Dissertation (MMedVet)--University of Pretoria, 2016. / Companion Animal Clinical Studies / MMedVet / Unrestricted
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Anestesisjuksköterskors strategier för att förebygga postoperativ smärta / The nurse anaesthesist`s strategies to prevent postoperative painAhlgren, Eva, Isacsson, Malin January 2014 (has links)
Sammanfattning Postoperativ smärtbehandling är otillräcklig trots ökad kunskap i smärtfysiologi och utvecklandet av nya farmakologiska riktlinjer. Obehandlad postoperativ smärta kan leda till komplikationer som fördröjd mobilisering, djup ventrombos, lungemboli, hjärtinfarkt, stroke och lunginflammation, vilka leder till ett ökat lidande för patienten både fysiskt och psykiskt samt ökade kostnader för samhället. Anestesisjuksköterskan lägger grunden för den postoperativa smärtbehandlingen före och under anestesin och ska arbeta preventivt för att patientens smärtbehandling ska vara tillräcklig. Syftet med studien var att belysa anestesisjuksköterskans strategier för att förebygga patientens postoperativa smärta efter generell anestesi. Semistrukturerade intervjuer genomfördes med fyra anestesisjuksköterskor på ett västsvenskt sjukhus och analyserades med kvalitativ innehållsanalys. Anestesisjuksköterskorna strävade efter att ge en individuell smärtbehandling till patienterna. Känslan som skapades vid det preoperativa mötet med patienten, typen av ingrepp, samt användandet av andra smärtbehandlingsmetoder påverkade planeringen av de intravenösa analgetikadoserna peroperativt. Genom att använda multimodal smärtbehandlingsmetod till patienter som opereras i generell anestesi skulle postoperativ smärta kunna förebyggas och bidra till minskat lidande för patienterna samt snabbare postoperativ återhämtning. Även vårdtiderna kan förkortas vilket kan leda till en samhällsekonomisk vinst. / Abstract The management of postoperative pain is insufficient despite increased knowledge of the physiology of pain and the development of new pharmacological guidelines. Postoperative pain left untreated can lead to delayed mobilization and secondary complications such as deep venous thrombosis, pulmonary embolism, cardiac infarction, stroke and pneumonia. The outcome is increased mental and physical disability for the patient and increased costs for the society. The nurse anesthesist has a crucial role in postoperative pain management before and during anesthesia and needs to work preventively to secure sufficient analgesia for the patient. The aim of this study was to enlighten the nurse anesthesist’s strategies to prevent postoperative pain after general anesthesia. Semi-structured interviews with four nurse anesthetists at a hospital in the Southwest of Sweden were analyzed with qualitative content analysis. The nurse anesthesists strived to individualize pain management. The effect of the atmosphere created at the preoperative meeting with the patient, the character of the planned procedure and the usage of other methods of pain management all affected peroperative planning of dosage of intravenous analgesics. By using multimodality analgesia in patients who have surgery under general anesthesia postoperative pain could be prevented and hence contribute to reduced patient disability and faster postoperative recovery. Furthermore, the in-hospital care time can be reduced which could mean socioeconomic benefits.
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A biopsychosocial approach to functioning, oral health and specialist dental health care in children with disabilities – Swedish and international perspectivesNorderyd, Johanna January 2017 (has links)
Introduction: Maintaining good oral health may be more important for children with disabilities than others, since problems with oral health may increase the impact of a disability, or the medical condition may increase the risk for poor oral health. In addition, the risk for oral health problems may be influenced by the functioning of the child. Functioning can also affect the child’s ability to cooperate in the dental setting, and how dental treatment is performed. A medical diagnosis alone does not provide enough information about a child’s functioning, nor oral health. Thus, there is a need for a holistic perspective of oral health and dental health care in children with disabilities. The International Classification of Functioning, Disability and Health - Children and Youth (ICF-CY) enables a structured assessment of the biopsychosocial consequences of a health condition. Aim: The overall aim of this thesis was to investigate how biopsychosocial factors relate to oral health and specialist dental health care in children with disabilities in a Swedish, and an international context, with special focus on the experience of dental treatment under general anaesthesia (DGA). Material and methods: The research was conducted using a quantitative, cross-sectional, comparative and descriptive design. An ICF-CY Checklist for Oral Health was completed with data from a structured interview with children 0-16 years old, referred for specialist dental health care, and their parents/carers. Additional information was retrieved from dental and medical records. Three groups were included in data analyses: one large international group of 218 children from Argentina, France, Ireland and Sweden; one large Swedish group with 99 children with complex disabilities; and one international group of children with disabilities and manifest dental caries from Argentina, France and Sweden. Results: The ICF-CY Checklist for Oral Health identified both common and varying functional, social and environmental aspects relevant for oral health and oral health care in children who had been referred to specialist dental clinics in four countries. Swedish children with caries experience had been referred to a paediatric dental specialist clinic at a significantly older age than caries-free children. The medical diagnoses were not significantly related to dental caries or child functioning in the large Swedish group with complex disabilities and low caries prevalence, nor was there a significant relationship between dental caries and child functioning. Collinearity between dental caries and problems in the functioning factor ’Interpersonal interactions andrelationships’ was observed in the international group of children with disabilities and manifest dental caries. DGA sessions with combined medical and dental treatment were common in the large Swedish study group. Children with experience of DGA had more severe problems in intellectual functions than those without experience of DGA. Problems in interpersonal interactions and relationships increased, while problems with mobility decreased, the likelihood for children having had experience of DGA. On international group level, dmft/DMFT was significantly higher in children with the experience of DGA than in those without DGA experience, but looking at Argentina, France and Sweden separately, this was not true for the Swedish children. There were significant, international differences between the prevalence of dmft/DMFT, DGA and environmental barriers. Conclusion: The biopsychosocial perspective, operationalised by the ICF-CY, contributes a holistic view on oral health and specialist dental health care in children with disabilities. In addition to certain differences, children with different health status from different countries share many functional and environmental aspects, important for oral health and dental health care. Early referral to a paediatric specialist dental clinic seemed favourable for oral health. The medical diagnosis was not related to child functioning or dental caries. Child functioning had a significant impact on DGA, and in children with disabilities and manifest dental caries, child functioning also had a correlation with caries. The dental caries burden was a stronger factor than functioning for the experience of DGA, however, dental health organisation and country context seemed to matter the most. Combining dental and medical procedures during the same GA session is good use of resources for both the individual and the society. To ensure children with complex disabilities to have the possibility of achieving equivalent good oral health as other children, DGA is one important factor.
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Avaliação biespectral, cardiorrespiratória e hemogasométrica em cadelas submetidas a ovariosalpingohisterectomia, tratadas com acepromazina associada ou não a meperidina e anestesiadas com halotano, isofluorano ou sevofluorano / Evaluation of the bispectral índex, cardiopulmonary and hemogasometric parameters in bitches submitted the ovariohysterectomy treated with acepromazina associate or not with meperidine and anesthetized with halothane, isoflurane or sevofluraneMattos Júnior, Ewaldo de 05 September 2008 (has links)
O presente estudo teve como objetivo avaliar os efeitos do halotano, isofluorano e sevofluorano sobre o índice biespectral, parâmetros cardiorrespiratórios e hemogasométricos em cadelas submetidas a ovariosalpingohisterectomia. Foram utilizadas 48 cadelas, sem raça definida, com peso médio de 15,09±4,29 kg, com idade média de 3,9±1,23 anos, encaminhadas para realização do procedimento de orivariosalpingohisterectomia. Os animais foram distribuídos aleatoriamente em seis grupos de oito animais, sendo designados como AH, AMH, AI, AMI, AS e AMS. Os animais dos grupos AH, AI e AS receberam acepromazina na medicação pré-anestésica na dose de 0,1 mg.kg-1 por via intramuscular. Já os animais dos grupos AMH, AMI e AMS receberam na medicação pré-anestésica acepromazina, na dose de 0,05 mg.kg-1, associada a meperidina, na dose de 3 mg.kg-1, administrados por via intramuscular. A indução da anestesia foi realizada com o auxílio de propofol, na dose de 5 mg.kg-1, lentamente por meio da via intravenosa. Uma vez que os animais apresentaram relaxamento mandibular foi realizada a entubação orotraqueal, sendo em seguida conectada ao circuito valvular circular do aparelho de anestesia, e mantidas em respiração espontânea com halotano (grupos AH e AMH), isofluorano (grupos AI e AMI) ou sevofluorano (grupos AS e AMS), diluídos em oxigênio a 100%. Foram mensurados o índice biespectral (BIS), eletromiografia (EMG), freqüência cardíaca (FC), pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), pressão arterial média (PAM), temperatura retal, freqüência respiratória (FR), tensão de dióxido de carbono no final da expiração (ETCO2), saturação periférica de oxigênio na oxi-hemoglobina (SpO2), relação entra a pressão parcial de oxigênio no sangue arterial e a fração inspirada de oxigênio hemogasometria arterial (pH, PaCO<2, PaO2, HCO3- e DB). Os parâmetros verificados e registrados em todos os grupos desde M0 até M5, sendo estes: M0; 15 minutos após a administração da medicação pré-anestésica, M1; 10 minutos de manutenção anestésica, M2; ligadura do pedículo ovariano direito, M3; sutura da musculatura, M4; sutura de pele, M5; 10 minutos após o fim da administração do anestésico. Em todos os grupos houve forte correlação do índice biespectral e a fração expirada de anestésico. Quanto ao índice biespectral, o grupo AMH apresentou índices inferiores em M2 quando comparado com AI, AMI e AS; neste mesmo momento AI apresentou índices superiores em relação a AMS. Não houve diferença entre os grupos estudados em relação aos parâmetros cardiovasculares. Todos os agentes causaram depressão respiratória, evidenciado pelo incremento na PaCO2, e a ocorrência de acidemia. Conclui-se que os três agentes avaliados possuíram correlação inversa com o índice biespectral, o grupo AMS apresentou valores inferiores de BIS, todos os agentes promoveram estabilidade cardiovascular e de maneira semelhante, desencadearam depressão respiratória e acidemia. / The objective of this study was evaluation effects of the halothane, isoflurane and sevoflurane on bispectral index, cardiopulmonary and hemogasometrics parameters in bitches undergoing ovariohysterectomy. Fourth-eight mongrel bitches (weight: 15,09±4,29 kg) with 3,9±1,23 years old, send to HOVET-USP for surgical procedure of ovariohysterectomy. The animals were randomly allocated in six grupos of eight animals, designed with AH, AMH, AI, AMI, AS e AMS. The animals of the AH, AI and AS group were premedicated with acepromazine (0,1 mg.kg-1, i.m.) and the animals of the AMH, AMI and AMS groups receive acepromazine (0,05 mg.kg-1, i.m.) and meperidine (3 mg.kg-1, i.m.). Fifteen minutes later, propofol was titrated to allow endotracheal intubation and connected in valvular circuit of anesthesia machine and was maintained in spontaneously breathing with halotane (groups AH and AMH), isoflurane (AI and AMI) and sevoflurane (AS and AMS) in 100% oxygen delivery. Bispectral index (BIS), heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), rectal temperature (RT), respiratory rate (RR), end-tidal of carbon dioxide (ETCO2), peripheral oxihemoglobin saturation, relationship of the arterial oxygen pressure and inspiration fraction of oxygen, inspiration fraction of anesthetics, end-tidal anesthetics, and gasometrical parameters (pH, PaCO2, PaO2, HCO3- and BD) was evaluated. The parameters was evaluated in all groups in moments M0 to M5, M0 fifteen minutes after de pre-medication administration; M1, ten minutes of anesthetic maintains; M2, transfixation of left ovarian; M3 muscle suture; M4, skin suture, M5, ten minutes of the end of anesthetic. All groups were having strong correlation of the bispectral index and end-tidal anesthetic. The AMH group has minor values of bispectral index in M2 when compare with AI, AMI and AS groups; in this moment AI group present to values when compare with AMS. The cardiovascular parameters havent difference between groups. All agents caused reduction of respiratory function, evidenced for increase in PaCO2 and acidemia. The tree agents has inverse correlation with bispectral index, the AMS group, present minor values of BIS, all agents promoted cardiovascular stability and decrease of respiratory function.
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Modélisation mathématique pour l'étude des oscillations neuronales dans des réseaux de mémoire hippocampiques pendant l'éveil et sous anesthésie générale / Mathematical Modelling of Neural Oscillations in Hippocampal Memory Networks during Waking and under General AnaesthesiaGiovannini, Francesco 19 September 2017 (has links)
La mémoire est communément définie comme la capacité de coder, stocker et rappeler les informations que nous avons perçues. Lorsque nous traversons le monde, nous ressentons des stimuli, nous assistons à des événements, nous constatons des faits, nous étudions des concepts et nous acquérons des compétences. Bien que la mémoire soit un comportement humain inné et familier, les mécanismes cérébraux qui nous fournissent de telles facultés sont loin d'être compris. Des études expérimentales ont montré que, lors des tâches de mémoire, certaines structures cérébrales présentent une activité synchrone qui est censée être corrélée avec le maintien à court terme des stimuli saillants. L'objectif de cette thèse est d'utiliser la modélisation mathématique biologiquement inspirée et des simulations d'activité neuronale pour éclairer les mécanismes permettant l'émergence de ces oscillations synchrones liées à la mémoire. Nous nous concentrons en particulier sur l'activité mnémonique de l'hippocampe pendant l'état éveillé, et l'amnésie et la consolidation inattendue de la mémoire sous anesthésie générale. Nous commençons par présenter un modèle détaillé de neurone pyramidal qui se trouve couramment dans les zones CA3 et CA1 de l'hippocampe. Stimulé par une courte impulsion de courant, le neurone produit une activité persistante maintenue pour de longues périodes (> 30s) au-delà du stimulus uniquement par des récepteurs calciques non spécifiques (CAN). Les paramètres du modèle sont dérivés des enregistrements in vitro de neurones hippocampiques réalisés par nos collaborateurs Beate Knauer et Motoharu Yoshida à l'Université de la Ruhr à Bochum, en Allemagne. Par la suite, nous étudions la dynamique d'une population de ces neurones pyramidaux-CAN interconnectés. Nous supposons que les réseaux de neurones à tir persistant pourraient fournir le mécanisme neuronale pour la maintenance des oscillations hippocampiques mnésiques. Nos résultats montrent que le réseau génère une activité oscillante auto-soutenue dans la fréquence thêta. Lors de la connexion du réseau pyramidal-CAN à des interneurones inhibiteurs, la dynamique du modèle révèle que l'inhibition rétroactive améliore la robustesse des oscillations thêta rapides, en resserrant la synchronisation des neurones pyramidaux. Nous démontrons que, dans le modèle, la fréquence et la puissance spectrale des oscillations sont modulées uniquement par le courant CAN, permettant une large gamme de fréquences d'oscillation dans la bande theta. Il s'agit d'un mécanisme biologiquement plausible pour la maintenance des oscillations thêta synchrones dans l'hippocampe qui vise à étendre les modèles traditionnels d'activité rythmique hippocampique entraînée par le septum. En outre, nous présentons une étude approfondie des effets perturbateurs de l'anesthésie générale sur les oscillations gamma dans l'hippocampe. Nous introduisons un nouveau modèle qui prend en compte les quatre principaux effets de l'agent anesthésique propofol sur les récepteurs GABAA. Nos résultats indiquent que l'inhibition tonique médiée par le propofol contribue à améliorer la synchronisation du réseau dans un réseau d'interneurones de l'hippocampe. Cette synchronisation améliorée pourrait fournir une explication possible pour l'apparition d'une conscience intra-opératoire, d'une formation explicite de la mémoire et même d'une excitation paradoxale sous anesthésie générale, en facilitant la communication entre structures cérébrales qui ne devraient pas être autorisées à le faire lorsqu'elles sont anesthésiées. En conclusion, les résultats décrits dans cette thèse fournissent de nouvelles idées sur les mécanismes sous-jacents de l'activité neuronale mnémonique, à la fois au cours du réveil et de l'anesthésie, en ouvrant des voies convaincantes pour les travaux futurs sur les applications cliniques qui s'attaquent aux maladies de la mémoire neurodégénératives et la surveillance de l'anesthésie. / Memory is commonly defined as the ability to encode, store, and recall information we perceived. As we experience the world, we sense stimuli, we witness events, we ascertain facts, we study concepts, and we acquire skills. Although memory is an innate and familiar human behaviour, the interior workings of the brain which provide us with such faculties are far from being fully unravelled. Experimental studies have shown that during memory tasks, certain brain structures exhibit synchronous activity which is thought to be correlated with the short-term maintenance of salient stimuli. The objective of this thesis is to use biologically-inspired mathematical modelling and simulations of neural activity to shed some light on the mechanisms enabling the emergence of these memory-related synchronous oscillations. We focus in particular on hippocampal mnemonic activity during the awake state, and the amnesia and paradoxical memory consolidation occurring under general anaesthesia. We begin by introducing a detailed model of a type of persistent-firing pyramidal neuron commonly found in the CA3 and CA1 areas of the hippocampus. Stimulated with a brief transient current pulse, the neuron displays persistent activity maintained solely by cholinergic calcium-activated non-specific (CAN) receptors, and outlasting the stimulus for long delay periods (> 30s). Our model neuron and its parameters are derived from experimental in-vitro recordings of persistent firing hippocampal neurons carried out by our collaborators Beate Knauer and Motoharu Yoshida at the Ruhr University in Bochum, Germany. Subsequently, we turn our attention to the dynamics of a population of such interconnected pyramidal-CAN neurons. We hypothesise that networks of persistent firing neurons could provide the neural mechanism for the maintenance of memory-related hippocampal oscillations. The firing patterns elicited by this network are in accord with both experimental recordings and modelling studies. In addition, the network displays self-sustained oscillatory activity in the theta frequency. When connecting the pyramidal-CAN network to fast-spiking inhibitory interneurons, the dynamics of the model reveal that feedback inhibition improves the robustness of fast theta oscillations, by tightening the synchronisation of the pyramidal CAN neurons. We demonstrate that, in the model, the frequency and spectral power of the oscillations are modulated solely by the cholinergic mechanisms mediating the intrinsic persistent firing, allowing for a wide range of oscillation rates within the theta band. This is a biologically plausible mechanism for the maintenance of synchronous theta oscillations in the hippocampus which aims at extending the traditional models of septum-driven hippocampal rhythmic activity. In addition, we study the disruptive effects of general anaesthesia on hippocampal gamma-frequency oscillations. We present an in-depth study of the action of anaesthesia on neural oscillations by introducing a new computational model which takes into account the four main effects of the anaesthetic agent propofol GABAergic hippocampal interneurons. Our results indicate that propofol-mediated tonic inhibition contributes to enhancing network synchronisation in a network of hippocampal interneurons. This enhanced synchronisation could provide a possible mechanism supporting the occurrence of intraoperative awareness, explicit memory formation, and even paradoxical excitation under general anaesthesia, by facilitating the communication between brain structures which should supposedly be not allowed to do so when anaesthetised. In conclusion, the findings described within this thesis provide new insights into the mechanisms underlying mnemonic neural activity, both during wake and anaesthesia, opening compelling avenues for future work on clinical applications tackling neurodegenerative memory diseases, and anaesthesia monitoring
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