Aqueous tissue extracts of Conyza canadensis inhibit the germination and shoot growth of three native herbs with no autotoxic effects

Conyza canadensis is a widespread weed species forming dense populations in most regions of China. Petri dish bioassays with aqueous extracts of the aboveground parts and roots of C. canadensis at three concentrations (0.05, 0.1, and 0.2 g mL-1) were undertaken to investigate the autotoxic effects of C. canadensis, and the possible effects on three dominant native weed species, Plantago asiatica, Digitaria sanguinalis and Youngia japonica. The results showed that seed germination and the shoot length of three native species were significantly inhibited by aqueous extracts of C. canadensis at almost all concentrations that generally increased with increasing extract concentration. However, the seed germination and shoot length of C. canadensis itself was not significantly affected by the same extracts at all concentrations. These results suggested that the potential allelopathic compounds produced by the tissue of C. canadensis may contribute to its invasive success in invading southern China.

An overview of invasive plants in Brazil

Alien plants are known to occur in Brazil since the 18th century when African grasses started to be recorded in pastures near Rio de Janeiro. In the beginning of the 19th century two royal decrees (July, 1809 and July, 1810) offered grants and tax exemption to everyone who would introduce plants of economic value. Nowadays, there are 117 plant species recognized as invasive or established and with invasive potential in Brazil and an unknown number of introduced plant species. Some of the most pervasive invasive species are Artocarpus heterophyllus Lam. and Hedychium coronarium König in tropical ombrophilous forest, Hovenia dulcis Thunb. in subtropical ombrophilous forest and subtropical semi-deciduous forest, Pinus taeda L. and Pinus elliottii Engelm. in subtropical ombrophilous forest and steppe, Prosopis juliflora (Sw.) DC. in stepic-savanna, Tecoma stans (L.) Juss. ex Kunth in tropical and subtropical semi-deciduous forest, Melinis minutiflora P. Beauv. in the Brazilian savannas, and Eragrostis plana Nees in the steppe. The purpose of this article is to fill a knowledge gap on alien species that are invasive in Brazil and where they are invading by summarizing data obtained by joint efforts of the Hórus Institute for Environmental Conservation and Development, The Nature Conservancy (TNC), the Inter-American Biodiversity Information Network (IABIN) invasive species thematic network (I3N), and the Brazilian Ministry of Environment (MMA) in the last six years.

Effects of naltrexone and cross-tolerance to morphine in a learned helplessness paradigm

Opiates have been implicated in learned helplessness (LH), a phenomenon known to be related to opiate stress-induced analgesia (SIA). In the present study, we investigated the role of opiates in the induction of LH and SIA under different conditions. Adult female Wistar rats were trained either by receiving 60 inescapable 1-mA footshocks (IS group, N = 114) or by confinement in the shock box (control or NS group, N = 92). The pain threshold of some of the animals was immediately evaluated in a tail-flick test while the rest were used 24 h later in a shuttle box experiment to examine their escape performance. The opiate antagonist naltrexone (0 or 8 mg/kg, ip) and the previous induction of cross-tolerance to morphine by the chronic administration of morphine (0 or 10 mg/kg, sc, for 13 days) were used to identify opiate involvement. Analysis of variance revealed that only animals in the IS group demonstrated antinociception and an escape deficit, both of which were resistant to the procedures applied before the training session. However, the escape deficit could be reversed if the treatments were given before the test session. We conclude that, under our conditions, induction of the LH deficit in escape performance is not opiate-mediated although its expression is opiate-modulated

Experimental anxiety and the reinforcing effects of ethanol in rats

In order to examine the relationship between anxiety and reinforcing effects of alcohol, drug-naive male Wistar rats weighing 250-300 g were classified as "anxious" and "non-anxious" in the elevated plus-maze test. A conditioned place preference test was then used to investigate the reinforcing effects of ethanol (EtOH) on these animals. On 2 alternate days, groups of "anxious", "non-anxious" and "normal" rats received intraperitoneal (ip) injections of EtOH (0.5, 1.0 or 1.5 g/kg) immediately before a 15-min confinement to the white compartment. On the 2 intervening days the same rats received ip injections of saline before confinement to the opposite compartment. On day 5, a 15-min free-choice test was carried out with no injections. Rats classified as "anxious" showed a significant, though not dose-dependent preference for all doses of ethanol compared to saline-treated animals. These data demonstrate that rats regarded as "anxious" are more sensitive to the reinforcing effects of EtOH than "non-anxious" and "normal" Wistar rats and emphasize the relevance of the basal levels of anxiety of rats when trying to detect the reinforcing effects of EtOH.

Environmental blue light prevents stress in the fish Nile tilapia

The present study aimed to test the effects of blue, green or white light on the stress response of the Nile tilapia, Oreochromis niloticus (L.). Each color was tested on two groups of isolated adult Nile tilapia (8 replicates each): one being subjected to confinement stress, and the other not (control). A different environmental color was imposed on each compartment by covering the light source with cellophane of the respective color (green or blue; no cellophane was used for white light). The intensity of green, white and blue lights was 250, 590 and 250 lux, respectively. Basal plasma cortisol levels were determined for each fish prior to the experimental procedures. The fish were confined by being displaced toward one side of the aquarium using an opaque partition for 1 h both in the morning and the afternoon of the two consecutive days of the test. At the end of this 48-h period, plasma cortisol levels were measured again. Basal cortisol levels (ng/ml) were similar for each group (ANOVA, F(2;42) = 0.77, P = 0.47). Thus, plasma cortisol levels were analyzed in terms of variation from their respective basal level. After confinement, plasma cortisol levels were not increased in fish submitted to a blue light environment. Thus, blue light prevents the confinement-induced cortisol response, an effect not necessarily related to light intensity.

L-histidine enhances learning in stressed zebrafish

The aim of the present study was to determine the effect of the histaminergic precursor L-histidine and the H3 receptor antagonist thioperamide on the learning process of zebrafish submitted or not to confinement stress. On each of the 5 consecutive days of experiment (D1, D2, D3, D4, D5), animals had to associate an interruption of the aquarium air supply with food offering. Non-stressed zebrafish received an intraperitoneal injection of 100 mg/kg L-histidine, 10 mg/kg thioperamide or saline after training. Stressed animals received drug treatment and then were submitted to confinement stress for 1 h before the learning procedure. Time to approach the feeder was measured (in seconds) and was considered to be indicative of learning. A decrease in time to approach the feeder was observed in the saline-treated group (D1 = 141.92 ± 13.57; D3 = 55 ± 13.54), indicating learning. A delay in learning of stressed animals treated with saline was observed (D1 = 217.5 ± 25.66). L-histidine facilitated learning in stressed (D1 = 118.68 ± 13.9; D2 = 45.88 ± 8.2) and non-stressed (D1 = 151.11 ± 19.20; D5 = 62 ± 14.68) animals. Thioperamide inhibited learning in non-stressed (D1 = 110.38 ± 9.49; D4 = 58.79 ± 16.83) and stressed animals (D1 = 167.3 ± 26.39; D5 = 172.15 ± 27.35). L-histidine prevented the increase in blood glucose after one session of confinement (L-histidine = 65.88 ± 4.50; control = 53 ± 3.50 mg/dL). These results suggest that the histaminergic system enhances learning and modulates stress responses in zebrafish.

Meat quality characteristics of exotic and SPRD crossbred goats from the semiarid region

Thirty-two intact male goats from four genetic groups (eight pure-bred Boers, eight ¾ Boer + ¼ SPRD crossbreeds, eight ½ Boer + ½ SPRD crossbreeds, and eight ½ Anglo Nubian + ½ SPRD crossbreeds) were evaluated for meat quality. The goats were reared in confinement and slaughtered at the average live weight of 29 kg. Temperature and pH decrease in the longissimus dorsi muscle was determined for 24 hours, and analyses of colour, cooking loss, water-holding capacity, and sensory attributes were also performed. Genotype significantly (P < 0.05) influenced the confinement period; ½ Boer + ½ SPRD crossbreeds required the most time in confinement to reach the target weight, while the pure-bred Boers required the least time. Genotype also significantly influenced (P < 0.05) the weight loss due to cooking, shearing force, colour (intensity of yellowness and luminescence), and the sensory attributes of flavour, odour, and raw colour of the meat. The crossing of exotic Boer and Anglo Nubian breeds with the native SPRD resulted in a goat meat of high quality.

Organizational creativity – Hegemonic and alternative discourses

SUMMARY Organizational creativity – hegemonic and alternative discourses Over the course of recent developments in the societal and business environment, the concept of creativity has been brought into new arenas. The rise of ‘creative industries’ and the idea of creativity as a form of capital have attracted the interests of business and management professionals – as well as academics. As the notion of creativity has been adopted in the organization studies literature, the concept of organizational creativity has been introduced to refer to creativity that takes place in an organizational context. This doctoral thesis focuses on organizational creativity, and its purpose is to explore and problematize the hegemonic organizational creativity discourse and to provide alternative viewpoints for theorizing about creativity in organizations. Taking a discourse theory approach, this thesis, first, provides an outline of the currently predominant, i.e. hegemonic, discourse on organizational creativity, which is explored regarding themes, perspectives, methods and paradigms. Second, this thesis consists of five studies that act as illustrations of certain alternative viewpoints. Through these exemplary studies, this thesis sheds light on the limitations and taken-for-granted aspects of the hegemonic discourse and discusses what these alternative viewpoints could offer for the understanding of and theorizing for organizational creativity. This study leans on an assumption that the development of organizational creativity knowledge and the related discourse is not inevitable or progressive but rather contingent. The organizational creativity discourse has developed in a certain direction, meaning that some themes, perspectives, and methods, as well as assumptions, values, and objectives, have gained a hegemonic position over others, and are therefore often taken for granted and considered valid and relevant. The hegemonization of certain aspects, however, contributes to the marginalization of others. The thesis concludes that the hegemonic discourse on organizational creativity is based on an extensive coverage of certain themes and perspectives, such as those focusing on individual cognitive processes, motivation, or organizational climate and their relation to creativity, to name a few. The limited focus on some themes and the confinement to certain prevalent perspectives, however, results in the marginalization of other themes and perspectives. The negative, often unintended, consequences, implications, and side effects of creativity, the factors that might hinder or prevent creativity, and a deeper inquiry into the ontology and epistemology of creativity have attracted relatively marginal interest. The material embeddedness of organizational creativity, in other words, the physical organizational environment as well as the human body and its non-cognitive resources, has largely been overlooked in the hegemonic discourse, although thereare studies in this area that give reason to believe that they might prove relevant for the understanding of creativity. The hegemonic discourse is based on an individual-centered understanding of creativity which overattributes creativity to an individual and his/her cognitive capabilities, while simultaneously neglecting how, for instance, the physical environment, artifacts, social dynamics and interactions condition organizational creativity. Due to historical reasons, quantitative as well as qualitative yet functionally- oriented studies have predominated the organizational creativity discourse, although studies falling into the interpretationist paradigm have gradually become more popular. The two radical paradigms, as well as methodological and analytical approaches typical of radical research, can be considered to hold a marginal position in the field of organizational creativity. The hegemonic organizational creativity discourse has provided extensive findings related to many aspects of organizational creativity, although the con- ceptualizations and understandings of organizational creativity in the hegemonic discourse are also in many respects limited and one-sided. The hegemonic discourse is based on an assumption that creativity is desirable, good, necessary, or even obligatory, and should be encouraged and nourished. The conceptualiza- tions of creativity favor the kind of creativity which is useful, valuable and can be harnessed for productivity. The current conceptualization is limited to the type of creativity that is acceptable and fits the managerial ideology, and washes out any risky, seemingly useless, or negative aspects of creativity. It also limits the possible meanings and representations that ‘creativity’ has in the respective discourse, excluding many meanings of creativity encountered in other discourses. The excessive focus on creativity that is good, positive, productive and fits the managerial agenda while ignoring other forms and aspects of creativity, however, contributes to the dilution of the notion. Practices aimed at encouraging the kind of creativity may actually entail a risk of fostering moderate alterations rather than more radical novelty, as well as management and organizational practices which limit creative endeavors, rather than increase their likelihood. The thesis concludes that although not often given the space and attention they deserve, there are alternative conceptualizations and understandings of organizational creativity which embrace a broader notion of creativity. The inability to accommodate the ‘other’ understandings and viewpoints within the organizational creativity discourse runs a risk of misrepresenting the complex and many-sided phenomenon of creativity in organizational context. Keywords: Organizational creativity, creativity, organization studies, discourse theory, hegemony

Oeuvres médicales de GUY DE CHAULIAC, LANFRANC, Jean LE LIEVRE, HIPPOCRATE, etc.

Contient : Calendrier français à l'usage de Toulouse ; Table du contenu de ce recueil ; Figures et vers français sur les quatre complexions de l'homme « sanguin, colorique, fleumatique et milencolique » ; Tables astronomiques ; « Taula per saber la calitat de las planetas » ; « Taula de la luna per conoysc en cal signe es cada jorn » ; « Taula per saber la hora de las plan[e]tas » ; « Disputacions de cyreurgie sur les condicions de tout le corps, ordonnées sur les oeuvrez de maistre Guidon de Caillac, maistre en medecine. Pour ce que selon Galien, in libro XVIJ° de utilitate particularium, capitulo penultimo, quatre utilités et prouffis sont... — ... est dit proprement pannicule. Expliciunt disputaciones » ; « L'Anothomie mise en disputacions. Cyreurgie est une science qui enseigne la maniere comment ont doit ouvrer... — ... En tout le grant pié y a XXX os. Explicit, » etc. (Figure du squelette humain, fol. 38 v°) ; « Le formulaire de maistre Lenfranc, doctour en medecine, qu'il envoya à son fils Bernard pour luy donner doctrine et congnoissance de cyrurgie en petite forme. Honorable Bernard, je Alenfranc entens de faire ung livre... — ... tu pourras savoir de plus grans choses. Explicit » ; « Le formulaire des aydes des apostemez, postulé et ordonné par maistre Guidon de Cailhac, cyreurgien et maistre en medicine, fait et composé à Montpellier, en l'an de Nostre S[eigneur] M. IIIe. XL. Pour ce que selon G[alien] ou III. de ingenio sanitatis, commancement de la science de ouvrer... — ... est à presumer que vous le savez » ; « Le formulaire des aydes des playes et des ulceres, ordonnées en Avignon par maistre Guidon de Cailhac, qui adonc estoit medecin du pape Clement, en l'an mil trois cens et quarente. Pour la doubte de oblier la necessité... — ... laver avecques de sang chault de bestez » ; « La deuxieme doctrine de la formacion des remedez... des maladies de la teste jusques es piez, selon la diversité des membres... Cy après mettrons les aydes des playes du chief... — ... et fiat emplastrum et est loé » ; « Aucunes bonnes receptes aprouvées par pluseurs ou fait de cyreurgie. Pour clistere. ???... » ; « Les proprietez de certaines eauez esprouvées par pluseurs docteurs en medecine. Eau de saulgie vaut contre toute paralisie... » — A la suite sont différentes recettes, parmi lesquelles la liste des jours périlleux de l'année (fol. 160) ; « Aucunez questions touchant le fait de flebotomye, qui sont extraictez et prises au VIJe livre de Guidon de Cailhac, qui est dit Antidotaire... Qu'est saignée ? Saignée ou flebothomie est incision de vaynez... — ... maladies moult mauvaises et perilleuses » ; « Ung petit traictié fait et compilé par maistre Jehan Le Lievre, tresexcellent maistre et docteur en medecine, sur le fait du nombre de la declairacion des vaynes qui sont assizes sur le corps de la personne. Cy après s'ensuit le nombre de la declairacion... Et premierement dit que au front en a une... — ... sur le corps est plus a plain declairé. Expliciunt les disputacions des saignées par ordre composées et le traictié sur ladite matiere de Me Jehan Le Lievre, docteur en medecine » ; « Le livre des secrez des dames, lequel est deffendu à reveler, sur peine d'escomeniment, en la Clementine, à nulle femme ne à nul homme, se il n'est de l'office de cyreurgie. Une dame m'a prié par courtoisie loyale... — ... avecques vin blanc et tantost enfantera » ; « Le chapitre des aydes de la mayre [matrice] des dames et de leurs medecinez. Il y a pluseurs femmes qui ont la maire chaulde... — ... jusques que le sang soit restraint » ; « Le meilleur livre que Ypocras eust en sa vie, qui traitte de la congnoissance de la vie et de la mort... Ypocras qui en son temps estoit le plus noble... — ... guarira au plaisir de Dieu. Cy finist le secret d'Ypocras » ; « Collacion pour congnoistre toutez les complexions selon la parolle de Me Albubert, dont Rasis, le noble et tresexcellent docteur parle en son livre. Les corps qui sont en complexion colorique... — ... plus fermez et fortez en judicature, etc. » ; « Certaynes curez et regimens d'aucunez oeuvrez perticulieres, faictes par ma[i]stre Jehan Piscis, docteur en medecine et chancellier de la noble faculté... à Montpellier. Et premierement pour le halaynement. Tu eviteras l'air froit... — ... (Ungant... contre la douleur des reins...) des devant dictez herbes ana. m.j. » ; « Aucunez proprietez de certainez viandes,... par maistre Jehan Piscis,... pour donner bonnez et malez humeurs selon la complexion des corps humains. Les viandes qui engendrent bon sang... — ... qui engendrent milencolie. » (Suivent, fol. 317, différentes formules de remedes) ; « Les cynonismes de maistre Guidon de Gailhac [Chauliac], maistre et docteur en medecyne, composez selon l'alphabetum... Aqua, c'est eaue et est la premiere des froides... — ... Usifur,... in secundo cum stipticitate » ; « Le livre des constellacions, pour savoir en quelle constellacion est homme né, et pour savoir les adventurez qui luy doyvent advenir, selon les dis des grans philosophez Tholomeus et Aristote. Premierement pour savoir la mort et la vie... — ... par le monde serchant son adventure. Cy finissent les XII signez et VII planettez » ; A la fin, on a biffé la mention : « Sed libre est de Piare d'Anjou, barbier de monseigneur le cardinal d'Alebret et sergent d'armes de nostre saint pere le Pape et serviteur de monseigneur le cardinal de Roan, et fut acheptay l'an mil CCCC LII »

Learning and healing: a wellness pedagogy for Aboriginal teacher education /

During the last 30 years Aboriginal peoples in Canada have made steady progress in reclaiming the responsibility for the education of their young people, especially in primary and secondary school. In comparison the education and or training of adult populations has not kept pace and many socioeconomic and sociocultural indicators demonstrate a ' , continued confinement of those populations to the margins of the dominant society of Canada. It is the adults, the mothers and the fathers, the grandmothers and grandfathers, the aunties and uncles that are the first teachers of the next generation and the nature of these relationships replicates the culture of unwellness in each subsequent generation through those teachers. There are few examples in the Aboriginal adult education literatures that give voice to the educational experience of the Learner. This study addresses that gap by exploring the perspectives embedded in the stories of a Circle of Learners who are, or were enrolled in the Bachelor of Education in Aboriginal Adult Education program at Brock University. That Circle of 1 participants included 9 women and 1 man, 6 of whom were from various i Anishinabek nations while 4 represented the Hotinonshd:ni nations in southern Ontario. They are an eclectic group, representing many professions, age groups, spiritual traditions, and backgrounds. This then is their story, the story of the heaming and Healing pedagogy and an expanded vision of Aboriginal education and research at Brock University.

"The whole earth as village" : a chronotopic analysis of Marshall McLuhan's "Global Village" and Patrick McGoohan's The Prisoner

Marshall McLuhan's "global village", and his theories on communications and technology, in conjunction with Patrick McGoohan's television series The Prisoner (ATV, 1967-1968) are explored in this thesis. The Prisoner, brainchild of McGoohan, is about the abduction and confinement of a British government agent imprisoned within the impenetrable boundaries of a benign but totalitarian city -state called "The Village". The purpose of his abduction and imprisonment is for the extraction of information regarding his resignation as a government spy. Marshall McLuhan originally popularized the phrase "the global village" in The Gutenberg Galaxy: The Making o/the Topographic Man (1962), asserting that, "The new electronic interdependence recreates the world in the image of a global village" (p. 31). This thesis argues that valid parallels exist between McGoohan's conception of "village", as manifested in The Prisoner, and McLuhan's global village. The comprehensive methodological stratagem for this thesis includes Marshall McLuhan's "mosaic" approach, Mikhail Bakhtin's concept ofthe "chronotope", as well as a Foucauldian genealogicallhistorical discourse analysis. In the process of deconstructing McLuhan's texts and The Prisoner as products of the 1960s, an historical "constellation" (to use Walter Benjamin's concept) of the same present has been executed. By employing this synthesized methodology, conjunctions have been made between McLuhan's theories and the series' main themes of bureaucracy as dictatorship, the perversion of science and technology, freedom as illusion, and the individual in opposition to the collective. A thorough investigation of the global village and The Prisoner will determine whether or not Marshall McLuhan and/or Patrick McGoohan visualize the village as an enslaving technological reality.

Etude théorique des propriétés électroniques et optiques des super-réseaux de Si/SiO2

FRANCAIS: L'observation d'une intense luminescence dans les super-réseaux de Si/SiO2 a ouvert de nouvelles avenues en recherche théorique des matériaux à base de silicium, pour des applications éventuelles en optoélectronique. Le silicium dans sa phase cristalline possède un gap indirect, le rendant ainsi moins intéressant vis-à-vis d'autres matériaux luminescents. Concevoir des matériaux luminescents à base de silicium ouvrira donc la voie sur de multiples applications. Ce travail fait état de trois contributions au domaine. Premièrement, différents modèles de super-réseaux de Si/SiO2 ont été conçus et étudiés à l'aide de calculs ab initio afin d'en évaluer les propriétés structurales, électroniques et optiques. Les deux premiers modèles dérivés des structures cristallines du silicium et du dioxyde de silicium ont permis de démontrer l'importance du rôle de l'interface Si/SiO2 sur les propriétés optiques. De nouveaux modèles structurellement relaxés ont alors été construits afin de mieux caractériser les interfaces et ainsi mieux évaluer la portée du confinement sur les propriétés optiques. Deuxièmement, un gap direct dans les modèles structurellement relaxés a été obtenu. Le calcul de l'absorption (par l'application de la règle d'or de Fermi) a permis de confirmer que les propriétés d'absorption (et d'émission) du silicium cristallin sont améliorées lorsque celui-ci est confiné par le SiO2. Un décalage vers le bleu avec accroissement du confinement a aussi été observé. Une étude détaillée du rôle des atomes sous-oxydés aux interfaces a de plus été menée. Ces atomes ont le double effet d'accroître légèrement le gap d'énergie et d'aplanir la structure électronique près du niveau de Fermi. Troisièmement, une application directe de la théorique des transitions de Slater, une approche issue de la théorie de la fonctionnelle de la densité pour des ensembles, a été déterminée pour le silicium cristallin puis comparée aux mesures d'absorption par rayons X. Une très bonne correspondance entre cette théorie et l'expérience est observée. Ces calculs ont été appliqués aux super-réseaux afin d'estimer et caractériser leurs propriétés électroniques dans la zone de confinement, dans les bandes de conduction.

De l'intérêt de l'enfant à la reconnaissance du droit à une vie familiale normale : chemin accessible pour les étrangers?

"Mémoire présenté à la Faculté des études supérieures en vue de l'obtention du grade de maître en droit option droit international"

Rôle des macrophages contre Candida albicans chez la souris transgénique exprimant le génome du VIH-1

La candidose oropharyngée (COP) constitue l’infection fongique opportuniste la plus fréquente chez les patients infectés au VIH-1. Malgré la profonde immunosuppression causée par le VIH-1, l’infection à Candida albicans demeure confinée au niveau de la muqueuse buccale sans dissémination aux organes profonds. La souris transgénique (Tg) CD4C/HIVMut exprimant le génome tronqué du VIH-1 présente, suite à l’inoculation orale de C. albicans, une COP chronique reproduisant fidèlement l’infection chez les patients séropositifs. Cette souris Tg a donc été utilisée afin de déterminer si les macrophages contribuent au confinement de C. albicans à la muqueuse buccale. Cette étude a permis de démontrer que i) les macrophages sont recrutés aux muqueuses buccale et gastrique en réponse au champignon malgré l’expression du transgène, ii) les macrophages de ces souris Tg présentent une polarisation vers un phénotype d’activation alternative et iii) la production de monoxyde d’azote par les macrophages des souris Tg n’est pas requise pour limiter la prolifération de Candida à la muqueuse buccale et pour restreindre sa dissémination aux organes profonds. Les macrophages ne semblent donc pas directement responsables de l’établissement de l’infection chronique à Candida chez la souris Tg CD4C/HIVMut.

Effet de l'histoire lumineuse sur la sensibilité rétinienne et circadienne à la lumière

L’objectif de ce projet de recherche était de vérifier la présence de changements de sensibilité de la rétine et du système circadien suite à deux semaines d'exposition à un milieu faiblement ou fortement éclairé, dans des conditions contrôlées en laboratoire. De plus, comme un changement de sensibilité peut modifier l'ajustement du système circadien au cycle jour-nuit extérieur, nous voulions également vérifier si la phase circadienne serait modifiée par le traitement et si la vigilance et l’humeur seraient affectées. Dix sujets ont été exposés à de la lumière tamisée (70 lux [LT]) et 10 ont été exposés à de la lumière vive (3000 lux [LV]) pendant 12 jours consécutifs en laboratoire de 8h45 à 19h00 tous les jours. L’exposition à la lumière a été mesurée 5 jours avant l’entrée au laboratoire dans l’habitat naturel du sujet et pendant la période en laboratoire à l’aide de l’Actiwatch-L®. La sensibilité rétinienne a été mesurée avant et après le traitement lumineux, par un électrorétinogramme (ERG) et la sensibilité circadienne, par le test de suppression de mélatonine salivaire. Tout au long du protocole, la vigilance, la somnolence et l'humeur ont été évaluées à plusieurs moments de la journée à intervalles prédéterminés. Après 12 jours d’exposition en lumière contrôlée, l’amplitude de l’onde-a au Vmax à l’ERG photopique a diminué en LV alors qu’elle a augmenté en LT. À l’ERG scotopique, une différence de sensibilité rétinienne (log K) entre les groupes avant le traitement expérimental s’est amenuisée à la fin du traitement (p=.053). La suppression de mélatonine après 90 minutes d’exposition au test de suppression a diminué en LV alors qu’il n’y a pas eu de modification en LT, cependant cette interaction n’était pas significative (p=.16). La phase circadienne des sujets exposés à LV a été devancée de 58 minutes (p=.04) alors qu’elle a été retardée de 26 minutes en LT (p=.32). Les mesures de vigilance subjective (EVA) ont indiqué que les sujets LV se considéraient plus éveillés que les sujets LT après le traitement (p=.02). Par contre, aucune différence n’est apparue quant aux mesures de performance psychomotrice ni de l’humeur. L’histoire lumineuse n’a pas modifié la sensibilité rétinienne dans le sens prévu par les hypothèses alors qu’il y a eu une tendance vers une augmentation de la sensibilité circadienne en condition de lumière tamisée. L’amélioration de la vigilance subjective après l’exposition en LV n’a pas été soutenue par les résultats de la performance psychomotrice. L’histoire lumineuse n’a eu aucun effet sur l’humeur des sujets. Cette étude souligne l’importance d’utiliser des mesures permettant de départager les effets immédiats d’un traitement lumineux des effets à long terme autant sur le plan rétinien que circadien. Il reste également complexe d’étudier en laboratoire des changements adaptatifs qui se produisent dans le milieu naturel en raison du confinement et des modifications physiologiques et psychologiques pouvant y être associées.