Niveaux de vigilance pendant et après une exposition à la lumière vive durant la nuit

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Acceptability and feasibility of a multidomain harmonized data collection protocol in youth mental health

Objective To develop targeted treatment for young people experiencing mental illness, a better understanding of the biological, psychological, and social changes is required, particularly during the early stages of illness. To do this, large datasets need to be collected using standardized methods. A harmonized data collection protocol was tested in a youth mental health research setting to determine its acceptability and feasibility. Method Eighteen participants completed the harmonization protocol, including a clinical interview, self-report measures, neurocognitive measures, and mock assessments of magnetic resonance imaging (MRI) and blood. The feasibility of the protocol was assessed by recording recruitment rates, study withdrawals, missing data, and protocol deviations. Subjective responses from participant surveys and focus groups were used to examine the acceptability of the protocol. Results Twenty-eight young people were approached, 18 consented, and four did not complete the study. Most participants reported positive subjective impressions of the protocol as a whole and showed interest in participating in the study again, if given the opportunity. Participants generally perceived the MRI and neurocognitive tasks as interesting and suggested that the assessment of clinical presentation could be shortened. Conclusion Overall, the harmonized data collection protocol appeared to be feasible and generally well-accepted by participants. With a majority of participants finding the assessment of clinical presentation too long and repetitive, the authors have made suggestions to shorten the self-reports. The broader implementation of this protocol could allow researchers to create large datasets and better understand how psychopathological and neurobiological changes occur in young people with mental ill-health

Dysconnection Topography in Schizophrenia Revealed with State-Space Analysis of EEG

BACKGROUND: The dysconnection hypothesis has been proposed to account for pathophysiological mechanisms underlying schizophrenia. Widespread structural changes suggesting abnormal connectivity in schizophrenia have been imaged. A functional counterpart of the structural maps would be the EEG synchronization maps. However, due to the limits of currently used bivariate methods, functional correlates of dysconnection are limited to the isolated measurements of synchronization between preselected pairs of EEG signals. METHODS/RESULTS: To reveal a whole-head synchronization topography in schizophrenia, we applied a new method of multivariate synchronization analysis called S-estimator to the resting dense-array (128 channels) EEG obtained from 14 patients and 14 controls. This method determines synchronization from the embedding dimension in a state-space domain based on the theoretical consequence of the cooperative behavior of simultaneous time series-the shrinking of the state-space embedding dimension. The S-estimator imaging revealed a specific synchronization landscape in schizophrenia patients. Its main features included bilaterally increased synchronization over temporal brain regions and decreased synchronization over the postcentral/parietal region neighboring the midline. The synchronization topography was stable over the course of several months and correlated with the severity of schizophrenia symptoms. In particular, direct correlations linked positive, negative, and general psychopathological symptoms to the hyper-synchronized temporal clusters over both hemispheres. Along with these correlations, general psychopathological symptoms inversely correlated within the hypo-synchronized postcentral midline region. While being similar to the structural maps of cortical changes in schizophrenia, the S-maps go beyond the topography limits, demonstrating a novel aspect of the abnormalities of functional cooperation: namely, regionally reduced or enhanced connectivity. CONCLUSION/SIGNIFICANCE: The new method of multivariate synchronization significantly boosts the potential of EEG as an imaging technique compatible with other imaging modalities. Its application to schizophrenia research shows that schizophrenia can be explained within the concept of neural dysconnection across and within large-scale brain networks

Élaboration et appréciation d’un cours sur les perspectives autochtones destiné à la formation à l’enseignement : le cas d’une université québécoise

The 62nd Call to Action of the Truth and Reconciliation Commission of Canada (TRC, 2015) urges governments to "provide the necessary funding to post-secondary institutions to educate teachers on how to integrate Indigenous knowledge and teaching methods into classroom" (p. 256). While the province of Quebec is just beginning this process, several Canadian universities have already begun the process of indigenizing their teacher education programs. This article recounts the journey of including a course on Indigenous perspectives in the Faculty of Education at the University of Sherbrooke, Quebec. The rationale and results are organized around two questions: How can a course on Indigenous perspectives be developed for pre- service teacher education programs? How do teacher candidates who have taken this course feel about it? Methodologically, this study follows a collaborative action research process. Eleven individuals participated in the development of the course and twenty-five teacher candidates provided feedback. Preliminary findings reveal the importance of co-construction and co- development of such a course by and with Indigenous individuals and school organizations. It is apparent that teacher candidates, both Indigenous and non-Indigenous, finished this course satisfied and committed to including Indigenous perspectives in their classrooms.Le 62e appel à l’action de la Commission de vérité et réconciliation (CVR) du Canada incite les gouvernements à « prévoir les fonds nécessaires pour permettre aux établissements d’enseignement postsecondaire de former les enseignants sur la façon d’intégrer les méthodes d’enseignement et les connaissances autochtones dans les salles de classe » (2015, p. 256). Plusieurs universités canadiennes ont déjà entamé l’autochtonisation de leurs programmes de formation à l’enseignement, alors que les universités québécoises francophones commencent à peine ce processus. Cet article relate le parcours d’inclusion d’un cours sur les perspectives autochtones à la Faculté d’éducation de l’Université de Sherbrooke, au Québec. L’argumentaire et les résultats s’articulent autour de ces deux questions : Comment développer un cours sur les perspectives autochtones pour les programmes de formation initiale à l’enseignement? Quelle appréciation en retirent les personnes étudiantes en enseignement ayant suivi ce cours? Méthodologiquement, cette étude suit un processus de recherche-action collaborative. Onze personnes ont participé à l’élaboration du cours et vingt-cinq personnes étudiantes en enseignement ont commenté le cours proposé. Les résultats préliminaires révèlent l’importance de la coconstruction et de la coréalisation d’un tel cours par et avec les personnes autochtones et les organisations scolaires autochtones. Il s’en dégage que les personnes étudiantes en enseignement, qu’elles soient Allochtones ou Autochtone, ressortent de ce cours satisfaites et s’engagent à inclure les perspectives autochtones dans leurs classes

International Congress on Schizophrenia Research: Introduction

Schizophrenia patients exhibit deficits in low-level processing, including pitch discrimination. This deficiency manifests in auditory evoked potentials (AEPs) as an impaired mismatch negativity (MMN), an electrophysiological response to infrequent target stimuli interspersed among frequent standard stimuli that typically peaks ~100ms post-stimulus onset. NMDA receptor antagonists have been shown to block MMN generation in both animals and humans, and NMDA dysfunction has been linked to the underlying pathophysiology of schizophrenia. A parallel line of evidence indicates that glutathione (GSH) regulation is perturbed in schizophrenia patients at the gene, protein and functional levels (Tosic et al., 2006). This GSH dysregulation leads to NMDA receptors' hypofunction through interaction with their redox site (Steullet et al., 2006). The present study aimed to modulate GSH levels in schizophrenia patients and assessed the effects of such a modulation on MMN generation mechanisms. N-acetyl-cysteine (NAC), a GSH precursor, was administered to schizophrenia patients, using a double-blind cross-over protocol. One group received NAC (2g/day) for 60 days and then placebo for another 60 days, and vice-versa for the second group. AEPs from patients were recorded at the onset of the protocol, at the point of cross-over, and at the end of the study. Participants were instructed to manually respond to target stimuli (2kHz pure tones occurring 20% of the time among 1kHz pure tones). Analyses of AEPs recorded at protocol onset indicated that patients (n=11) were significantly impaired in generating the MMN relative to age-matched controls (n=11). Specifically, the global field power (GFP), an index of AEP magnitude, was measured over the 70- 155ms post-stimulus interval and submitted to an analysis of variance (ANOVA). There was a significant interaction between population and stimulus frequency, indicating impaired MMN generation in patients at protocol onset. Analyses of AEPs recorded during administration of NAC (n=7) versus placebo (n=7) revealed the efficacy of this GSH precursor in modulating MMN generation mechanisms. ANOVA of GFP over the 70- 155ms post-stimulus interval, using stimulus frequency and treatment as within-participants variables, revealed a significant interaction and indicated that NAC can ameliorate MMN generation. We discuss these results in terms of potential therapeutic strategies for schizophrenia

Impaired mismatch negativity to frequency deviants in individuals at ultra-high risk for psychosis, and preliminary evidence for further impairment with transition to psychosis

© 2018 Elsevier BV. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Background There is evidence to suggest that people with established psychotic disorders show impairments in the mismatch negativity induced by a frequency-deviant sound (fMMN), and that these impairments worsen with the deterioration of psychotic symptoms. This study aimed to test whether individuals at ultra-high risk (UHR) for psychosis show pre-morbid impairments in fMMN, and if so, whether fMMN continues to deteriorate with transition to psychosis. Method fMMN was recorded in a cohort of UHR individuals (n = 42) and compared to healthy controls (n = 29). Of the 27 UHR participants who returned for a second EEG session, six participants had transitioned to psychosis by 12-month follow-up (UHR-T) and were compared to the 21 participants who did not transition (UHR-NT). Results fMMN amplitude was significantly reduced, relative to healthy controls, in the UHR cohort. Furthermore, UHR-T individuals showed a significant decrease in fMMN amplitude over the period from baseline to post-transition; this reduction was not observed in UHR-NT. Conclusions These results suggest that fMMN is abnormal in UHR individuals, as has repeatedly been found previously in people with established psychotic disorders. The finding that fMMN impairment worsens with transition to psychosis is consistent with the staging model of psychosis; however, caution must be taken in interpreting these findings, given the extremely small sample size of the UHR-T group

Development of the PSYCHS: Positive SYmptoms and Diagnostic Criteria for the CAARMS Harmonized with the SIPS

Aim: To harmonize two ascertainment and severity rating instruments commonly used for the clinical high risk syndrome for psychosis (CHR-P): the Structured Interview for Psychosis-risk Syndromes (SIPS) and the Comprehensive Assessment of At-Risk Mental States (CAARMS). Methods: The initial workshop is described in the companion report from Addington et al. After the workshop, lead experts for each instrument continued harmonizing attenuated positive symptoms and criteria for psychosis and CHR-P through an intensive series of joint videoconferences. Results: Full harmonization was achieved for attenuated positive symptom ratings and psychosis criteria, and modest harmonization for CHR-P criteria. The semi-structured interview, named Positive SYmptoms and Diagnostic Criteria for the CAARMS Harmonized with the SIPS (PSYCHS), generates CHR-P criteria and severity scores for both CAARMS and SIPS. Conclusions: Using the PSYCHS for CHR-P ascertainment, conversion determination, and attenuated positive symptom severity rating will help in comparing findings across studies and in meta-analyses