Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The research of neural mechanisms related to training of emotions has increased in recent years. Fear is a behavior originated in response to the dangers encountering by animals, originating in defensive responses displayed when exposed to threatening stimuli. Fear memory helps animals and humans recognize putative sources of danger and adopt the appropriate behavioral response. The primary neural circuits for fear acquisition and extinction involve connections between prefrontal cortex, ventral hippocampus and amygdala, and these áreas are modulated by brainstem networks. The nucleus (n.) incertus in the dorsal pontine tegmentum provides a strong GABAergic projection to these forebrain centers and is strongly activated by neurogenic stressors. In this study in male, adult rats, we injected miniruby anterograde tracer into n. incertus and delineated its projections to the amygdala; and examined the effect of electrolytic lesions of n. incertus on different stages of the fear conditioning-extinction process. N. incertus-derived nerve fibers were observed in anterior medial amygdala, endopiriform nucleus, intra-amygdala bed nucleus of stria terminalis, amygdalohippocampal transition area, and the ventromedial nucleus of the lateral amygdala, with a broad fiber band present between the basolateral amygdala and the olfactory nuclei of amygdala. In a conventional contextual fear conditioning paradigm, we compared freezing behavior in control (naïve) rats (n = 13), with that in rats after sham- or electrolytic lesions of n. incertus (n = 9/group). There were no differences between the three groups in the habituation, acquisition, or context conditioning phases; but n. incertus-lesioned rats displayed a markedly slower (delayed) extinction of conditioned freezing responses than sham/control rats; suggesting n. incertus-related circuits normally promote extinction through inhibitory projections to amygdala and prefrontal cortex. The results helps in understanding the neurobiological mechanisms involved and in development of the future biotechnological techniques to minimize the effects of disorders associated with fear in humans, such as panic, anxiety and posttraumatic stress disorder. / A pesquisa dos mecanismos neurais relacionados à formação das emoções tem crescido nos últimos anos. O medo é um comportamento originado em resposta aos perigos enfrentados pelos animais, tendo sua origem nas reações defensivas exibidas quando da exposição a estímulos ameaçadores. A memória do medo ajuda os animais e os seres humanos a reconhecem as fontes putativas de perigo e adotar a resposta comportamental apropriada. Os circuitos neurais primárias envolvidos nos mecanismo de aquisição de medo e extinção envolvem conexões entre o córtex pré-frontal, hipocampo ventral e a amígdala, e estas áreas são moduladas por redes do tronco cerebral. O núcleo incertus (NI) no tegmento dorsal pontino fornece uma forte projeção GABAérgica a estes centros prosencéfalicos e é fortemente ativado por estressores neurogênicos. Neste estudo em ratos adultos machos foi injetado o traçador anterógrado miniruby no NI, delineado as suas projeções para a amígdala e examinado o efeito de lesões eletrolíticas no NI sobre diferentes fases do processo de condicionamento do medo-extinção. Fibras derivadas do NI foram observadas na amígdala medial anterior, núcleo endopiriforme, parte intra-amígdala do núcleo do leito da estria terminalis, área de transição amígdala-hipocampal, e o núcleo ventromedial da amígdala lateral, com uma ampla faixa de fibra presentes entre a amígdala basolateral e os núcleos olfativos da amígdala. Em um paradigma de condicionamento contextual de medo convencional, comparou-se o comportamento de congelamento em ratos controle (não operados) (n = 13), com ratos operados sem lesão do NI e ratos com lesão do núcleo incertus (n = 9). Não houve diferenças entre os três grupos nas fases de habituação, aquisição ou condicionamento ao contexto, mas ratos com lesão no NI exibiram uma extinção nitidamente mais lenta (com atraso) de respostas condicionadas de congelamento em comparação com ratos operados sem lesão do NI e controles, sugerindo que circuitos NI relacionados normalmente promovem a extinção através de projeções inibitórias para a amígdala e o córtex pré-frontal. Os resultados encontrados auxiliam na compreensão dos mecanismos neurobiológicos envolvidos e no desenvolvimento futuro de técnicas terapêuticas biotecnológicas visando minimizar os efeitos dos distúrbios associados ao medo em humanos, a exemplo do pânico, ansiedade patológica e estresse pós-traumático.

Alors que les principales activités d’un chef de projet s’effectuent à travers le processus de communication, on observe que de nombreux projets font l'objet de retards, dérives ou défauts de spécifications. Excès de mesures pour prévenir le risque ou gestion déficiente de la communication laissant trop de place à l’incertitude ? La Théorie de la Réduction de l’Incertitude développée par Berger et Calabrese (1975) dans le champ de la communication ne permet pas de totalement saisir comment un chef de projet dissipe l’incertitude existante entre les acteurs. En revisitant un projet opérationnel dans le cadre d’une recherche-action, nous nous employons à identifier comment incertitude et communication s’influencent et se structurent mutuellement. Nous avons convoqué l’approche constructiviste et la théorie de l’acteur-réseau de Callon et Latour pour accéder au sens de cette relation circulaire. Nous avançons les hypothèses selon lesquelles : - L’incertitude est un actant qui intervient dans la construction du réseau (au sens de Bruno Latour (2007) « ce qui est tracé par les traductions »).- Le processus de communication diffère suivant la nature de l’incertitude rencontrée ou ressentie. - Le processus de communication performe et scelle les relations en les rendant si coûteuses à défaire et si économiques à maintenir, qu’elles deviennent irréversibles. L’approche communicationnelle de l’incertitude mettra en évidence plusieurs caractéristiques de cet actant, comme sa capacité à peupler un « réseau de manques », la façon dont le réseau se hiérarchise pour faire sens, la description du processus d’estimation continue dont il fait l’objet (l’Incertus). Si nous concevons l’incertitude comme l’attribut d’un phénomène alors la « communication-incertitude » fabrique le sens en même temps qu’elle détermine la valeur de cet attribut. En positionnant l’incertitude comme un phénomène socialement construit, nous présentons un modèle constructiviste de « communication-incertitude » où l’observateur est un acteur intentionnel limité par des contraintes (Boudon, 2009) et proposons de distinguer la nature de l’incertitude suivant une typologie : l’incertitude de variabilité (inhérente à la variabilité des choses), l’incertitude épistémique ambiguë ou non (due à l’imperfection de nos connaissances) et l’incertitude d'échelle (en rapport avec l’imperfection de nos modèles de représentations). Dans ce mouvement vers l’irréversibilité, les processus de communication participent au remplacement des médiateurs (qui transforment, redonnent du sens, font faire des choses inattendues) par des intermédiaires (qui transmettent, transfèrent sans modifier) et les actants les plus réversibles sont évacués vers la périphérie du réseau. / While the main activities of a project manager are done through the communication process, it is observed that many projects are subject to delays, excesses or defects specifications. Excess of measurements to prevent the risk ? Defective management of the communication which leaves too much place to uncertainty ? The Theory of Uncertainty Reduction developed by Berger and Calabrese (1975) in the field of communication does not fully understand how a project dissipates the existing uncertainty between actors. By revisiting an operational project within the framework of action research, we strive to identify how uncertainty and communication influence and form themselves mutually. We used the constructivist approach and the actor-network theory of Callon and Latour to reach the meaning of this circular relationship. We advance the following hypotheses: - Uncertainty is a nonhuman actor involved in the construction of the network (as defined by Bruno Latour (2007) "which is drawn by translations"). - The communication process differs according to the nature of the uncertainty encountered or felt. - The communication process performs and seals relationships by making them so expensive to undo and so economic to maintain, that they become irreversible. The communicational approach of the uncertainty will highlight several features of this nonhuman actor, as its ability to populate a "network of gaps", the way the network ranks into a hierarchy to make sense, the description of the continuous process of estimation (the Incertus). If we conceive uncertainty as an attribute of a phenomenon, then "communication-uncertainty" makes sense at the same time it determines the value of this attribute. By positioning uncertainty as a socially constructed phenomenon, we present a constructivist model of "communication-uncertainty" where the observer is an intentional actor limited by constraints (Boudon, 2009). We propose to distinguish the nature of uncertainty following a typology: the variability uncertainty (inherent variability of things), the epistemic uncertainty ambiguous or not (due to the imperfection of our knowledge) and the scale uncertainty (in touch with the imperfection of our models of representations). In this movement towards irreversibility, the communication processes involved in replacing mediators (which transform, give meaning, make unexpected things do) by intermediaries (which transmit, transfer without changing) and the most reversible nonhumans actors are evacuated to the network edge.