Orientador: Prof. Dr. Marcelo Salvador Caetano / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Neurociência e Cognição, 2016. / Em um esquema de reforço de múltiplos intervalos fixos, diferentes intervalos de tempo são sinalizados por diferentes estímulos ambientais que adquirem controle sobre o comportamento. Trabalhos anteriores no nosso laboratório mostraram que o desempenho temporal é controlado não só por estímulos externos, mas também por aspectos temporais da tarefa de acordo com a ordem na qual os diferentes intervalos ¿ misturados em todas as tentativas ou em blocos de várias tentativas ¿ são treinados. Este projeto de pesquisa visa descrever as condições de treino sob as quais os estímulos assumem controle sobre o comportamento dos ratos numa tarefa de estimação temporal. As variáveis manipuladas são o número de pares de estímulo-intervalo treinados (Experimento I), o tamanho do bloco de tentativas repetidas de cada par de estímulo-intervalo (Experimento II) e a ordem de apresentação das condições de treino em bloco e misturado (Experimento III). Os resultados encontrados sugerem que o desempenho temporal dos animais na tarefa foi controlado por regularidades temporais e não pelos estímulos externos disponíveis quando treinados em blocos de várias tentativas consecutivas com o mesmo par de estímulo-intervalo. Ainda, que alguns animais parecem deixar de usar os estímulos externos como pista preditiva do intervalo quando a ordem de apresentação passa de treino misturado para treino em bloco. Uma possível explicação para estes resultados é que as pistas temporais sombreiam os estímulos visuais pelo controle do desempenho temporal. Estes resultados com ratos têm sido expandidos e observados em estudos com humanos, portanto os resultados deste projeto têm relevância no entendimento de estratégias de aprendizagem que podem ser aplicadas ao comportamento humano. / In a multiple fixed intervals schedule of reinforcement, different time intervals are signaled by different environmental stimuli which acquire control over behavior. Previous work in our lab has shown that temporal performance is controlled not only by external stimuli, but also by temporal aspects of the task depending on the order in which the different intervals ¿ intermixed across trials or in blocks of several trials ¿ are trained. The aim of this project was to describe the training conditions under which the stimuli acquire control over temporal performance. We manipulated the number of stimulus-interval pairs trained (Experiment I), the number of consecutive trials of each stimulus-interval pair per training block (Experiment II), and the order in which the two training types are presented - in blocks then intermixed, and vice-versa (Experiment III). The results suggest that, when trained in blocks of several consecutive trials of the same stimulus-interval pair, temporal performance was controlled by temporal regularities across trials and not by the external stimuli available. Moreover, some animals seem to stop relying on the external stimuli as predictive cues of the intervals when the training condition changes from intermixed to blocked. One possible account for those data is that temporal cues overshadow visual stimuli for the control of temporal performance. Similar results have also been observed in human studies, which suggest that temporal regularity is a salient cue used to guide behavior in temporal tasks across species.

La particularité du temps est de n’être l’objet d’aucun système sensoriel, contrairement aux stimulations lumineuses ou sonores. Quelles sont les opérations cognitives, en dehors de l’horloge interne, qui sont impliquées dans le fait que nous soyons capables de dire qu’une durée est plus courte qu’une autre ? Quelle est la dynamique de ces processus ? Pour le déterminer, nous nous sommes basés sur l’étude du comportement et des potentiels évoqués dans des tâches de discrimination temporelle. Plusieurs objectifs ont été poursuivis. Premièrement, il s’agissait de déterminer les processus, ainsi que leur dynamique, pouvant être mis en évidence dans la manipulation de l’information temporelle. Un deuxième objectif consistait à préciser l’impact du contexte sur le recrutement et la dynamique de ces processus. Un dernier objectif était d’explorer l’effet de la durée présentée et celui de la consigne sur les processus impliqués dans le traitement temporel et sur leur dynamique. Les résultats principaux sont les suivants. Premièrement, des composantes évoquées frontopariétales indexaient la comparaison, la prise de décision, l’attention et la mémoire de travail. Deuxièmement, ces activités étaient modulées par la saillance perceptive. En outre, une durée particulièrement saillante permet de terminer la comparaison avant la fin du stimulus. Troisièmement, le contexte de présentation modulait les activités évoquées associées au moment où la décision est prise. En conclusion, cette thèse met en évidence que les processus à l’œuvre dans la perception temporelle ne sont pas spécifiques au traitement des durées, comme l’attention et la mémoire de travail. / The peculiarity of time is that it is not the object of any sensory system, contrary to the stimuli consisting of light or sound. What cognitive operations, apart from the internal clock, are involved in the fact that we are able to say that one duration is shorter than another? What is the dynamic of these processes? To determine it, we have based ourselves on the study of the behavior and the event-related potentials in several tasks of temporal discrimination. Several objectives were adressed. The first objective was to determining the processes and associated ERPs, as well as their dynamics that can be demonstrated in the manipulation of the temporal information. A second aim was to specify the impact of the context on recruitment and the dynamics of these processes. A final objective was to investigate the effect of the duration presented and that of the instruction on the processes involved in the temporal treatment as well as on their dynamics. The main results are as follows. First, frontoparietal event-related components indexed comparison, decision making, orientation of attention and working memory. Secondly, these activities were modulated by the perceptual salience of a duration. Moreover, a particularly salient duration allow the end of the comparison before the end of the stimulus. Third, the impact of the presentation context modulated the evoked activities associated at the time the decision is made. In conclusion, this thesis shows that the processes at work in time perception are not specific to the treatment of durations, such as attention and working memory.