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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Effects of Voluntary Physical Rehabilitation on Neurogenesis In SVZ And Functional Recovery After Ischemic Stroke

Balakrishnan, Anuranjani 17 December 2018 (has links)
No description available.
22

Contralateral Prophylactic Mastectomy: An Exploratory Approach to Understanding the Decision Making Process

Greener, Judith Robin January 2015 (has links)
The rate at which women choose mastectomy has grown dramatically, and of particular note is the increase in contralateral prophylactic mastectomy (CPM). For women with no history of breast cancer or genetic risk, CPM represents a treatment decision that does not offer better long-term outcomes than the decision not to remove a healthy breast and may be associated with increased surgical risk and interventions, increased cost to the healthcare system, and potential adverse psycho-social outcomes. To better understand the decision making process regarding the election of CPM among women with early stage unilateral breast cancer, with no family history or genetic risk, a three-phase exploratory study was conducted. Qualitative in-depth interviews were conducted with healthcare providers who have close interaction with women during the decision making process (N=3) and patients who made a surgical decision about breast cancer treatment within the past three years (N=11). These two phases informed the design of the quantitative internet survey, conducted among women diagnosed with early stage breast cancer in the process of making a surgical decision (N=336). The survey design was also guided by an existing model for treatment decision making which uses a social ecological framework (Revenson & Pranikoff, 2005). In addition to descriptive analyses, perceptual mapping was utilized to understand patients’ conceptualizations of the relative importance of factors considered during the decision making process, and AdSAM® was used to gauge emotional response. Results suggest that women more likely to elect CPM demonstrate an emotional response to a generalized fear of cancer, along with the need to take control of their situation. In addition, retrospective interviews emphasized somewhat different reasons for electing CPM, highlighting the importance of prospective research in studying the decision making process. / Public Health
23

Estudo da orelha contralateral na otite média crônica : avaliação auditiva

Silva, Denis Lessa da January 2013 (has links)
Uma das condições mais comuns responsável pela perda auditiva durante a infância é a Otite Média (OM). A OM ainda é considerada “questão de saúde pública” devido à sua alta prevalência e distribuição mundial. Há poucos estudos na literatura que relatam as alterações na orelha contralateral (OCL) em pacientes com otite média crônica (OMC). Para enfatizar esses conceitos e analisar com mais profundidade a prevalência de bilateralidade na OMC, há vários anos iniciamos uma linha de pesquisa, focalizando três cenários diferentes: a histopatologia (ROSITO, COSTA, SCHARCHEN, 2007); o padrão clínico e otoscópico (COSTA et al., 2008) e a fisiologia (função auditiva) no presente estudo. Objetivo: Avaliar a função auditiva da OCL em pacientes com OMC através do gap aéreo-ósseo. Comparar os dados audiométricos da OCL levando em conta se o paciente apresenta Otite Média Crônica não Colesteatomatosa (OMCNC) ou Otite Média Crônica Colesteatomatosa (OMCC) na orelha principal (OP). Métodos: Estudo transversal, comparativo e contemporâneo, com 1000 pacientes com diagnóstico de OMC submetidos a exame otorrinolaringológico, videotoscopia e audiometria tonal liminar (ATL). Resultados: A prevalência de gap aéreo-ósseo foi de aproximadamente 40%, tanto na amostra total e na análise estratifica por tipo de OM (na amostra geral houve 392 (39,2%) pacientes, no grupo com OMCNC houve 279 (40,8%), e no grupo com OMCC foram 113 (37,17%). Conclusões: Assim como os achados de estudos clínicos e histopatológicos, a prevalência de alterações audiológicas na OCL foi elevada, evidenciando o caráter bilateral na OMC. / Otitis media (OM) is one of the leading causes of hearing loss in childhood. Due to its high prevalence and worldwide distribution, OM is still regarded as a public health issue. Nevertheless, few studies have assessed involvement of the contralateral ear (CLE) in patients with chronic otitis media (COM). To demonstrate the bilateral nature of COM, we designed three distinct studies, which focused on histopathology and anatomy, clinical findings and physiology (both previously published), and, finally, auditory function. Objective: To measure auditory function in the CLE in a sample of COM patients by means of air-conduction thresholds, bone-conduction thresholds, and the air-bone gap, and to compare CLE audiometry findings in patients with non-cholesteatomatous (NC-COM) or cholesteatomatous chronic otitis media (CCOM). Methods: This was a cross-sectional, contemporary and comparative study of 1000 patients with a diagnosis of COM. Clinical ear examination, video otoscopy, and pure-tone audiometry (PTA) were performed. Results: The overall prevalence rate of air-bone gap was approximately 40%, both in the total sample and after stratification by type of OM (393 [39.2%] patients overall, 279 [40.3%] in the NC-COM group, 113 [37.17%] in the CCOM group). Conclusions: As did clinical and histopathology findings in previous studies, audiological evaluation revealed a substantial prevalence of CLE involvement, providing evidence of the bilateral nature of COM.
24

Estudo da orelha contralateral na otite média crônica : avaliação auditiva

Silva, Denis Lessa da January 2013 (has links)
Uma das condições mais comuns responsável pela perda auditiva durante a infância é a Otite Média (OM). A OM ainda é considerada “questão de saúde pública” devido à sua alta prevalência e distribuição mundial. Há poucos estudos na literatura que relatam as alterações na orelha contralateral (OCL) em pacientes com otite média crônica (OMC). Para enfatizar esses conceitos e analisar com mais profundidade a prevalência de bilateralidade na OMC, há vários anos iniciamos uma linha de pesquisa, focalizando três cenários diferentes: a histopatologia (ROSITO, COSTA, SCHARCHEN, 2007); o padrão clínico e otoscópico (COSTA et al., 2008) e a fisiologia (função auditiva) no presente estudo. Objetivo: Avaliar a função auditiva da OCL em pacientes com OMC através do gap aéreo-ósseo. Comparar os dados audiométricos da OCL levando em conta se o paciente apresenta Otite Média Crônica não Colesteatomatosa (OMCNC) ou Otite Média Crônica Colesteatomatosa (OMCC) na orelha principal (OP). Métodos: Estudo transversal, comparativo e contemporâneo, com 1000 pacientes com diagnóstico de OMC submetidos a exame otorrinolaringológico, videotoscopia e audiometria tonal liminar (ATL). Resultados: A prevalência de gap aéreo-ósseo foi de aproximadamente 40%, tanto na amostra total e na análise estratifica por tipo de OM (na amostra geral houve 392 (39,2%) pacientes, no grupo com OMCNC houve 279 (40,8%), e no grupo com OMCC foram 113 (37,17%). Conclusões: Assim como os achados de estudos clínicos e histopatológicos, a prevalência de alterações audiológicas na OCL foi elevada, evidenciando o caráter bilateral na OMC. / Otitis media (OM) is one of the leading causes of hearing loss in childhood. Due to its high prevalence and worldwide distribution, OM is still regarded as a public health issue. Nevertheless, few studies have assessed involvement of the contralateral ear (CLE) in patients with chronic otitis media (COM). To demonstrate the bilateral nature of COM, we designed three distinct studies, which focused on histopathology and anatomy, clinical findings and physiology (both previously published), and, finally, auditory function. Objective: To measure auditory function in the CLE in a sample of COM patients by means of air-conduction thresholds, bone-conduction thresholds, and the air-bone gap, and to compare CLE audiometry findings in patients with non-cholesteatomatous (NC-COM) or cholesteatomatous chronic otitis media (CCOM). Methods: This was a cross-sectional, contemporary and comparative study of 1000 patients with a diagnosis of COM. Clinical ear examination, video otoscopy, and pure-tone audiometry (PTA) were performed. Results: The overall prevalence rate of air-bone gap was approximately 40%, both in the total sample and after stratification by type of OM (393 [39.2%] patients overall, 279 [40.3%] in the NC-COM group, 113 [37.17%] in the CCOM group). Conclusions: As did clinical and histopathology findings in previous studies, audiological evaluation revealed a substantial prevalence of CLE involvement, providing evidence of the bilateral nature of COM.
25

Estudo da orelha contralateral na otite média crônica : avaliação auditiva

Silva, Denis Lessa da January 2013 (has links)
Uma das condições mais comuns responsável pela perda auditiva durante a infância é a Otite Média (OM). A OM ainda é considerada “questão de saúde pública” devido à sua alta prevalência e distribuição mundial. Há poucos estudos na literatura que relatam as alterações na orelha contralateral (OCL) em pacientes com otite média crônica (OMC). Para enfatizar esses conceitos e analisar com mais profundidade a prevalência de bilateralidade na OMC, há vários anos iniciamos uma linha de pesquisa, focalizando três cenários diferentes: a histopatologia (ROSITO, COSTA, SCHARCHEN, 2007); o padrão clínico e otoscópico (COSTA et al., 2008) e a fisiologia (função auditiva) no presente estudo. Objetivo: Avaliar a função auditiva da OCL em pacientes com OMC através do gap aéreo-ósseo. Comparar os dados audiométricos da OCL levando em conta se o paciente apresenta Otite Média Crônica não Colesteatomatosa (OMCNC) ou Otite Média Crônica Colesteatomatosa (OMCC) na orelha principal (OP). Métodos: Estudo transversal, comparativo e contemporâneo, com 1000 pacientes com diagnóstico de OMC submetidos a exame otorrinolaringológico, videotoscopia e audiometria tonal liminar (ATL). Resultados: A prevalência de gap aéreo-ósseo foi de aproximadamente 40%, tanto na amostra total e na análise estratifica por tipo de OM (na amostra geral houve 392 (39,2%) pacientes, no grupo com OMCNC houve 279 (40,8%), e no grupo com OMCC foram 113 (37,17%). Conclusões: Assim como os achados de estudos clínicos e histopatológicos, a prevalência de alterações audiológicas na OCL foi elevada, evidenciando o caráter bilateral na OMC. / Otitis media (OM) is one of the leading causes of hearing loss in childhood. Due to its high prevalence and worldwide distribution, OM is still regarded as a public health issue. Nevertheless, few studies have assessed involvement of the contralateral ear (CLE) in patients with chronic otitis media (COM). To demonstrate the bilateral nature of COM, we designed three distinct studies, which focused on histopathology and anatomy, clinical findings and physiology (both previously published), and, finally, auditory function. Objective: To measure auditory function in the CLE in a sample of COM patients by means of air-conduction thresholds, bone-conduction thresholds, and the air-bone gap, and to compare CLE audiometry findings in patients with non-cholesteatomatous (NC-COM) or cholesteatomatous chronic otitis media (CCOM). Methods: This was a cross-sectional, contemporary and comparative study of 1000 patients with a diagnosis of COM. Clinical ear examination, video otoscopy, and pure-tone audiometry (PTA) were performed. Results: The overall prevalence rate of air-bone gap was approximately 40%, both in the total sample and after stratification by type of OM (393 [39.2%] patients overall, 279 [40.3%] in the NC-COM group, 113 [37.17%] in the CCOM group). Conclusions: As did clinical and histopathology findings in previous studies, audiological evaluation revealed a substantial prevalence of CLE involvement, providing evidence of the bilateral nature of COM.
26

Cross Education; : The effect of 10 weeks of unilateral resistance training on strength and hypertrophy

Derakhti, Mikael, Åkerlund, John January 2016 (has links)
Abstract    Aim    The main purpose of this study was to investigate Cross Education (CE), and how gender, detraining and leg dominance affects CE in previously untrained subjects when conducting a unilateral resistance training program. We also investigated if unilateral resistance training can give a hypertrophic response.    Method   Twenty healthy previously untrained individuals, 10 females and 10 males, were recruited as volunteer participants. The participants were randomly assigned to train either left or right leg. The training intervention was 10 weeks (34 sessions) of unilateral resistance training in the leg press and leg extension, sixteen of the participants fulfilled the criteria for inclusion. After two initial familiarization the participants trained conventional resistance training three times a week (week 1-3, 5-7 and 9-10) and Blood Flow Restriction Training (BFRT) five times a week (week 4 and 8). One repetition maximum for both legs in the leg press and leg extension was tested pre-, post and post20 to the training intervention as well as ultrasound measurements of muscle thickness.   Results    The ten-week training period resulted in a significant increase of maximal strength for the untrained leg 18,9 %, (16,6) (p < 0,01) in the leg press and 6,7 %, (3,7) (p < 0,05) in the leg extension. When comparisons between gender were made only men had a significant increase 26,5 %, (16,7) (p < 0,01) in the leg press and 9,9 %, (4,7) (p < 0,05) in the leg extension. Also, we saw a significant difference between women and men on a group level. Comparisons of dominant vs non-dominant leg showed that training the dominant leg resulted in a significant increase of maximal strength in the untrained leg in both the leg press 22 %, (17,9) (p < 0,01) and leg extension 10,1 %, (4,3) (p < 0,05). The maximal strength in the untrained leg was not significantly altered by the detraining period and a significant increase of muscle thickness could be seen in the untrained leg at MP50 4,7 %, (1,3) (p < 0,01).   Conclusion    The conclusions are that a ten week unilateral resistance training intervention results in a CE effect for men but not for women and that this type of training also can result in an increased muscle thickness in the untrained leg. Our findings also supports that training the dominant limb has superior effect on achieving a CE effect. Lastly we conclude that a twenty week detraining period did not affect the CE achieved strength. / Abstrakt    Syfte     Studiens huvudsakliga syfte var att undersöka Cross Education (CE) och hur kön, viloperiod och ben-dominans påverkar CE hos otränade individer när man undergår ett unilateralt styrketräningsprogram. Vi undersökte även om ett unilateral styrketräning kunde ge ett hypertrofisvar.    Metod    Tjugo friska otränade och för närvarande inaktiva individer, tio kvinnor och tio män rekryterades som frivilliga deltagare. Deltagarna randomiserades för att träna antingen vänster eller höger ben. Träningsperioden var tio veckor (trettiofyra pass) av unilateral styrketräning i benpress och benspark, sexton deltagare uppfyllde kriterierna för inkludering. Två initiala familjäriseringspass hölls varefter träningen delades in i två typer av träning, dels konventionell styrketräning tre gånger i veckan (vecka 1-3, 5-7 och 9-10) och dels Blood Flow Restriction Training (BFRT) fem gånger i veckan (vecka 4 och 8). Före, efter och efter tjugo veckor testades one repetition maximum för båda benen i benpress och benspark samt att ultraljudsmätningar för muskeltjocklek utfördes.     Resultat    Den tio veckor långa träningsperioden resulterade i en signifikant ökning av den maximala styrkan för det otränade benet 18,9 % (16,6) (p < 0,010) i benpressen och 6,7 % (3,7) (p < 0,050) i bensparken. När jämförelser gjordes mellan könen så hade enbart män en signifikant ökning, 26,5 % (16,7) (p < 0,010) i benpressen och 9,9 % (4,7) (p < 0,050) i bensparken. Vi fann även att det var en signifikant skillnad mellan kvinnor och män på gruppnivå.   Jämförelser mellan dominant och icke-dominant ben visade att träning av det dominanta benet resulterade i en signifikant styrkeökning i både benpress 22 % (17,9) (p < 0,010) och benspark 10,1 % (4,3) (p < 0,050). Den maximala styrkan i det otränade benet påverkades inte signifikant av en viloperiod och en signifikant ökning i muskeltjocklek kunde ses i det otränade benet i MP50 4,7 % (1,3) (p < 0,010)    Konklusion    Slutsatserna är att en tio veckors unilateral styrketräningsintervention resulterar i en CE effekt hos män men inte hos kvinnor, och att denna typ av träning kan resultera i en ökad muskeltjocklek i det otränade benet. Våra fynd styrker att träning av den dominanta lemmen har större effekt på CE. Slutligen drar vi slutsatsen att en tjugo veckors viloperiod inte påverkar CE-styrkan.
27

Contralateral Suppression of Click Evoked Otoacoustic Emissions in Normal-Hearing Children

Oyler, R. F., Murnane, Owen D. 01 January 1997 (has links)
No description available.
28

FACTORS INFLUENCING PREFERENCE FOR SURGICAL CHOICE AMONG WOMEN WITH EARLY STAGE BREAST CANCER

Yackzan, Susan G. 01 January 2017 (has links)
Breast cancer is the most common cancer among women in the United States with over 60% of cases diagnosed as early stage disease. For those women without prohibiting clinical or cosmetic concerns, a choice between breast-conserving surgery and mastectomy can be made. Either choice confers equivalent survival. The decision-making process also involves consideration of recurrence risk as well as management of the unaffected, contralateral breast for both future surveillance and risk reduction. In recent years, increasing rates of mastectomy with contralateral prophylactic mastectomy have been reported among women with unilateral, early stage breast cancer. If eligible for a choice among surgical options, a woman’s decision becomes one of personal preference. The decision-making process is complex and involves consideration of potential benefits and harms with each option. The purpose of this dissertation was to: 1) analyze the psychometric properties of the Anxiety Subscale of the Depression Anxiety Stress Scale, 2) critically review Decisional Conflict Scales and 3) prospectively identify demographic, clinical, cognitive and affective factors influencing a woman’s decision to choose either breast conserving surgery or mastectomy with contralateral prophylactic mastectomy and to identify self-reported sources of information in the surgical decision-making process. Three manuscripts make up the dissertation. A secondary data analysis was conducted to test the psychometric properties of the Anxiety Subscale of the Depression Anxiety Stress Scale (DASS). The results of this analysis supported the reliability and validity of the DASS anxiety subscale. A critical review of decisional conflict measures for use with early stage breast cancer patients making surgical treatment decisions was conducted. The results of this review supported the use of Decisional Conflict Scales from a clinical and research perspective. Existing Decisional Conflict Scales show moderate to acceptable reliability. The first two manuscripts provided background and support for the use of scales included in the research study described in the third manuscript. This study was a prospective, exploratory, cross-sectional, mixed-methods study describing factors influencing preference for surgical choice among women with early stage breast cancer. A sample of 78 participants enrolled in the study, 47 who chose breast conserving surgery and 31 who chose mastectomy with contralateral prophylactic mastectomy. Differences were tested between the groups. Women who chose mastectomy with contralateral prophylactic mastectomy were younger, more likely to work full or part-time, had larger tumors and participated in preoperative genetic counselling. Women who chose breast conserving surgery were more likely to have participated in preoperative breast magnetic resonance imaging. Overall, women choosing either surgery were not experiencing severe levels of distress, depression, anxiety or stress although there were individual variations. Women choosing mastectomy with contralateral prophylactic mastectomy were more anxious and had more frequent intrusive thoughts about the diagnosis. They also had less decisional conflict as compared to women choosing breast conserving surgery. Information sources were similar but the most influential information source differed among the two groups. In both groups, intention for surgical choice was matched by the final decision. There are many factors influencing surgical choice among women with early stage breast cancer. Previous work has focused on clinical, demographic and diagnostic processes influencing the decision. With this study, evidence regarding the influence of cognitive and affective factors is described.
29

Cognitive training optimization with a closed-loop system

Roy, Yannick 08 1900 (has links)
Les interfaces cerveau-machine (ICMs) nous offrent un moyen de fermer la boucle entre notre cerveau et le monde de la technologie numérique. Cela ouvre la porte à une pléthore de nouvelles applications où nous utilisons directement le cerveau comme entrée. S’il est facile de voir le potentiel, il est moins facile de trouver la bonne application avec les bons corrélats neuronaux pour construire un tel système en boucle fermée. Ici, nous explorons une tâche de suivi d’objets multiples en 3D, dans un contexte d’entraînement cognitif (3D-MOT). Notre capacité à suivre plusieurs objets dans un environnement dynamique nous permet d’effectuer des tâches quotidiennes telles que conduire, pratiquer des sports d’équipe et marcher dans un centre commercial achalandé. Malgré plus de trois décennies de littérature sur les tâches MOT, les mécanismes neuronaux sous- jacents restent mal compris. Ici, nous avons examiné les corrélats neuronaux via l’électroencéphalographie (EEG) et leurs changements au cours des trois phases d’une tâche de 3D-MOT, à savoir l’identification, le suivi et le rappel. Nous avons observé ce qui semble être un transfert entre l’attention et la de mémoire de travail lors du passage entre le suivi et le rappel. Nos résultats ont révélé une forte inhibition des fréquences delta et thêta de la région frontale lors du suivi, suivie d’une forte (ré)activation de ces mêmes fréquences lors du rappel. Nos résultats ont également montré une activité de retard contralatérale (CDA en anglais), une activité négative soutenue dans l’hémisphère contralatérale aux positions des éléments visuels à suivre. Afin de déterminer si le CDA est un corrélat neuronal robuste pour les tâches de mémoire de travail visuelle, nous avons reproduit huit études liées au CDA avec un ensemble de données EEG accessible au public. Nous avons utilisé les données EEG brutes de ces huit études et les avons analysées avec le même pipeline de base pour extraire le CDA. Nous avons pu reproduire les résultats de chaque étude et montrer qu’avec un pipeline automatisé de base, nous pouvons extraire le CDA. Récemment, l’apprentissage profond (deep learning / DL en anglais) s’est révélé très prometteur pour aider à donner un sens aux signaux EEG en raison de sa capacité à apprendre de bonnes représentations à partir des données brutes. La question à savoir si l’apprentissage profond présente vraiment un avantage par rapport aux approches plus traditionnelles reste une question ouverte. Afin de répondre à cette question, nous avons examiné 154 articles appliquant le DL à l’EEG, publiés entre janvier 2010 et juillet 2018, et couvrant différents domaines d’application tels que l’épilepsie, le sommeil, les interfaces cerveau-machine et la surveillance cognitive et affective. Enfin, nous explorons la possibilité de fermer la boucle et de créer un ICM passif avec une tâche 3D-MOT. Nous classifions l’activité EEG pour prédire si une telle activité se produit pendant la phase de suivi ou de rappel de la tâche 3D-MOT. Nous avons également formé un classificateur pour les essais latéralisés afin de prédire si les cibles étaient présentées dans l’hémichamp gauche ou droit en utilisant l’activité EEG. Pour la classification de phase entre le suivi et le rappel, nous avons obtenu un 80% lors de l’entraînement d’un SVM sur plusieurs sujets en utilisant la puissance des bandes de fréquences thêta et delta des électrodes frontales. / Brain-computer interfaces (BCIs) offer us a way to close the loop between our brain and the digital world of technology. It opens the door for a plethora of new applications where we use the brain directly as an input. While it is easy to see the disruptive potential, it is less so easy to find the right application with the right neural correlates to build such closed-loop system. Here we explore closing the loop during a cognitive training 3D multiple object tracking task (3D-MOT). Our ability to track multiple objects in a dynamic environment enables us to perform everyday tasks such as driving, playing team sports, and walking in a crowded mall. Despite more than three decades of literature on MOT tasks, the underlying and intertwined neural mechanisms remain poorly understood. Here we looked at the electroencephalography (EEG) neural correlates and their changes across the three phases of a 3D-MOT task, namely identification, tracking and recall. We observed what seems to be a handoff between focused attention and working memory processes when going from tracking to recall. Our findings revealed a strong inhibition in delta and theta frequencies from the frontal region during tracking, followed by a strong (re)activation of these same frequencies during recall. Our results also showed contralateral delay activity (CDA), a sustained negativity over the hemisphere contralateral to the positions of visual items to be remembered. In order to investigate if the CDA is a robust neural correlate for visual working memory (VWM) tasks, we reproduced eight CDA-related studies with a publicly accessible EEG dataset. We used the raw EEG data from these eight studies and analysed all of them with the same basic pipeline to extract CDA. We were able to reproduce the results from all the studies and show that with a basic automated EEG pipeline we can extract a clear CDA signal. Recently, deep learning (DL) has shown great promise in helping make sense of EEG signals due to its capacity to learn good feature representations from raw data. Whether DL truly presents advantages as compared to more traditional EEG processing approaches, however, remains an open question. In order to address such question, we reviewed 154 papers that apply DL to EEG, published between January 2010 and July 2018, and spanning different application domains such as epilepsy, sleep, brain-computer interfacing, and cognitive and affective monitoring. Finally, we explore the potential for closing the loop and creating a passive BCI with a 3D-MOT task. We classify EEG activity to predict if such activity is happening during the tracking or the recall phase of the 3D-MOT task. We also trained a classifier for lateralized trials to predict if the targets were presented on the left or right hemifield using EEG brain activity. For the phase classification between tracking and recall, we obtained 80% accuracy when training a SVM across subjects using the theta and delta frequency band power from the frontal electrodes and 83% accuracy when training within subjects.
30

Optical imaging and two-photon microscopy study of hemodynamic changes contralateral to ictal focus during epileptiform discharges

Truong, Van Tri 04 1900 (has links)
Il est relativement bien établi que les crises focales entraînent une augmentation régionale du flot sanguin dans le but de soutenir la demande énergétique en hémoglobine oxygénée des neurones épileptiques. Des changements hémodynamiques précoces ont également été rapportés dans la région homologue controlatérale, bien que ceci ait été moins bien caractérisé. Dans cette étude, notre objectif est de mieux caractériser, lors de crises focales, la nature des changements hémodynamiques précoces dans la région homologue controlatérale au foyer épileptique. L'imagerie optique intrinsèque (IOI) et la microscopie deux-photons sont utilisées pour étudier les changements hémodynamiques dans la région homologue controlatérale au site de crises focales induites par l’injection de 4-aminopyridine (4-AP) dans le cortex somatosensitif ipsilatéral de souris. Dans l'étude d'IOI, des changements de l’oxyhémoglobine (HbO), de la désoxyhémoglobine (HbR) et du débit sanguin cérébral ont été observées dans la région homologue controlatérale au site de crises focales lors de toutes les crises. Toutefois, ces changements étaient hétérogènes, sans patron cohérent et reproduisible. Nos expériences avec la microscopie deux-photons n’ont pas révélé de changements hémodynamiques significatifs dans la région homotopique controlatérale lors de trains de pointes épileptiques. Nos résultats doivent être interprétés avec prudence compte tenu de plusieurs limitations: d’une part absence de mesures électrophysiologiques dans la région d’intérêt controlatérale au foyer simultanément à l’imagerie deux-photons et à l'IOI; d’autre part, lors des expériences avec le deux-photons, incapacité à générer de longues décharges ictales mais plutôt des trains de pointes, couverture spatiale limitée de la région d’intérêt controlatérale, et faible puissance suite au décès prématuré de plusieurs souris pour diverses raisons techniques. Nous terminons en discutant de divers moyens pour améliorer les expériences futures. / It has been well demonstrated that focal seizures are associated with a significant increase in regional cerebral blood flow to actively supply discharging neurons with oxygenated hemoglobin. There is also some evidence to suggest that focal seizures elicit early hemodynamic changes in the contralateral homotopic area, although this has been less well documented. In this study, we aim to better characterize the nature of early hemodynamic responses contralateral to the epileptic focus during seizures. We used intrinsic optical imaging (IOI) and two-photon laser microscopy to measure the hemodynamic changes in the homotopic contralateral area following focal seizures induced by an injection of 4-aminopyridine (4-AP) in the mouse somatosensory neocortex. In the study using IOI, oxyhemoglobin (HbO), deoxyhemoglobin (HbR) and cerebral blood flow (CBF) changes were observed in the homotopic area contralateral to the focus during all seizures. However, these changes were rather heterogenous, lacking any consistent or reproducible pattern. Our two-photon study showed no significant hemodynamic changes at the capillary level in the homotopic area contralateral to the ictal focus during epileptic spike trains. However, these findings must be interpreted cautiously in light of several limitations we encountered during the experiments. Specifically, we were unable to simultaneously record electrophysiology in the contralateral homotopic area. Furthermore, during our two-photon experiments, we failed to induce long ictal discharges (inducing only spike trains) had a limited sampling of the contralateral homotopic area and reduced power as a result of low mice survival rate. We conclude by providing alternatives to possibly improve future experiments.

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