Segmentation of experience and episodic memory across species

How continuous ongoing perceptual experience is processed by the brain and mind to form unique episodes in memory is a key scientific question. Recent work in Psychology and Neuroscience has proposed that humans perceptually segment continuous ongoing experience into meaningful units, which allows the successful formation of episodic memories. Despite accumulating work demonstrating that non- human animals also display a capability of episodic-‘like’ memory, whether non-human animals segment continuous ongoing experience into ‘meaningful’ episodic units is a question that has not been fully explored. Hence, the main goal of the research in this thesis aims to address whether a comparable segmentation process (or processes) of continuous ongoing experience occurs for non-human animals in their formation of episodic-like memory, as it does for humans in their formation of episodic memory. Chapter 2 argues that, similarly to humans, rats can use top-down like prediction-error processing in segmenting for subsequent memory to guide behaviour in an episodic-like spontaneous object recognition task. Chapter 3 suggests that mice readily incorporate conspecific-contextual information using episodic-like memory processing, indicating that conspecifics can act as a segmentation cue for non-human animals. Chapter 4 highlights that humans and rodents may similarly segment continuous ongoing experience during turns made around spatial boundaries. Chapter 5 argues that individual place cells can represent content of episodic nature, with the theoretical implication of this being discussed in relation to episodic memory. Thus, the results presented in this thesis, as well as re-interpretation of previous literature, would argue in favour of non-humans segmenting their experience for episodic-like memory. Finally, the evidence is evaluated in the context of whether episodic-like memory in non-human animals is simply just episodic memory as experienced in humans

Artificial Intelligence and Systems Theory: Applied to Cooperative Robots

This paper describes an approach to the design of a population of cooperative robots based on concepts borrowed from Systems Theory and Artificial Intelligence. The research has been developed under the SocRob project, carried out by the Intelligent Systems Laboratory at the Institute for Systems and Robotics - Instituto Superior Tecnico (ISR/IST) in Lisbon. The acronym of the project stands both for "Society of Robots" and "Soccer Robots", the case study where we are testing our population of robots. Designing soccer robots is a very challenging problem, where the robots must act not only to shoot a ball towards the goal, but also to detect and avoid static (walls, stopped robots) and dynamic (moving robots) obstacles. Furthermore, they must cooperate to defeat an opposing team. Our past and current research in soccer robotics includes cooperative sensor fusion for world modeling, object recognition and tracking, robot navigation, multi-robot distributed task planning and coordination, including cooperative reinforcement learning in cooperative and adversarial environments, and behavior-based architectures for real time task execution of cooperating robot teams

Short-term memory of temporal aspects of noxious and innocuous thermal sensation : psychophysical and fMRI studies

La douleur peut être considérée comme un système de protection qui signale une menace et qui nous avertit des dégâts imminents aux tissus. En tant que mécanisme de défense, il nécessite l'apprentissage et la mémoire des expériences du passé pour la survie et les comportements liés à la douleur. Par conséquent, notre expérience de la douleur actuelle est fortement influencée par les expériences antérieures et l'apprentissage. Cependant, malgré son importance, notre compréhension actuelle de l'interaction entre le système de la douleur et le système de mémoire est très limitée. La mémoire de la douleur est un sujet de recherche très vaste. Il nécessite une compréhension des mécanismes impliqués à chaque étape du système de mémoire (mémoire immédiate, à court terme et à long terme) et l'interaction entre eux. Parmi les étapes multiples de la mémoire, la mémoire à court terme de la douleur est une zone qui est moins recherchée, alors qu'il existe une énorme quantité de recherche neuroscientifique dans la mémoire à court terme sur d'autres modalités, en particulier la vision. L'étude de la mémoire à court terme de la douleur est particulièrement importante car cette trace de la mémoire à court terme de la douleur est ensuite convertie en mémoire à long terme et affecte ensuite les expériences futures de la douleur. Cette thèse est largement axée sur la mémoire à court terme de la douleur. La complexité et la multi dimensionnalité de la douleur ajoutent encore un autre élément à la recherche sur la mémoire de la douleur. Par exemple, la trace de la mémoire de la douleur peut contenir des traces de mémoire de diverses composantes de la douleur telles que la réponse sensorielle affective, cognitive et motrice et l'interaction entre elles. Par conséquent, une première étape dans l'exploration neuroscientifique de la mémoire de la douleur nécessite la réduction de l'expérience de la douleur tout en englobant tous ces différents composants à un seul composant. Dans la recherche présentée ici, nous avons généralement examiné cela par des instructions d'attention ‘ top-down’ pour assister à la dimension sensorielle de la douleur. La recherche précédente sur la mémoire à court terme de la douleur a également porté principalement sur la dimension sensorielle de la douleur. Cependant, parmi les dimensions sensorielles de la douleur, la mémoire à court terme de l'intensité et de la dimension spatiale de la douleur a fait l'objet de recherches antérieures. Malgré son importance, la dimension temporelle de la douleur est restée complètement inexplorée dans la recherche sur la mémoire de la douleur. La recherche menée dans cette thèse est consacrée à l'exploration de la mémoire à court terme de la durée de la douleur. La durée de la douleur peut être suivie de manière indépendante, mais peut également être suivie conjointement avec la dimension d'intensité telle que le suivi dynamique de l'intensité de la douleur dans le temps. Les études menées dans cette thèse traitent spécifiquement du traitement isolé de la durée de la douleur ainsi que du traitement conjoint de la dimension durée / intensité de la douleur. La première étude psychophysique a exploré la nature de la représentation mentale du modèle de mémoire de la douleur thermique dynamique et a également été conçue pour aborder les différences de la dimension sensorielle et affective de la douleur thermique dans la mémoire à court terme. La deuxième étude psychophysique portait sur les propriétés de la mémoire à court terme de la sensation thermique non douloureux en comparant le suivi dynamique de la sensation et le suivi isolé de la durée d'un événement thermique non douloureux. La troisième étude poursuit l'exploration du traitement dynamique de la durée conjointement avec l'intensité par rapport au traitement isolé de la durée dans la mémoire à court terme en utilisant des stimuli thermiques douloureuse une résonance magnétique fonctionnelle (IRMF). Dans l'ensemble, les résultats des études psychophysiques ont montré une transformation significative de la durée et de la dynamique de la sensation thermique douloureux et non-douloureux dans la mémoire à court terme; comme la perte d'informations somatosensorielles temporelles en mémoire. Nous avons en outre montré une amélioration du rappel de la durée dans le suivi dynamique de la durée, en comparaison avec le suivi de la durée isolée. Nous avons également montré des différences dans les corrélats neuronaux de la mémoire à court terme de la durée de douleur par rapport à la dynamique de douleur. L'étude de l'IRMF a montré des similitudes frappantes dans les corrélats neuronaux sous-jacents à la mémoire à court terme de douleur et d'autres modalités telles que la contribution des coticés fronto-pariétales ainsi que les corticaux sensoriels impliqués dans le traitement perceptuel.Pain can be viewed as a protective system that signals threat and alerts us to impending tissue damage. As a defense mechanism, it necessitates the learning and memory of past painful experiences for survival and pain-related behavior. Therefore our current pain experience is heavily influenced by previous experiences and learning. However, despite its importance, our current understanding of the interaction between the pain system and the memory system is very limited. Pain memory is a very broad topic of research on its own. It requires an understanding of the mechanisms involved at each stage of the memory system (immediate, short-term, and long-term memory), and the interaction among them. Among the multiple stages of memory, the short-term memory of pain is an area that is less researched, while there are enormous amount of neuroscientific research in short-term memory of other modalities, particularly vision. Investigation of the short-term memory of pain is especially important as the short-term memory trace of pain is converted to long-term memory and subsequently affects future pain experiences. This thesis is broadly focused on the short-term memory of pain. The complexity and multi-dimensionality of pain adds yet another element to the research on pain memory. For example, the memory trace of pain may contain memory traces of various components of pain such as sensory, affective, cognitive, and motoric responses, and the interactions among them. Therefore, an initial step in the neuroscientific exploration of pain memory requires narrowing down the pain experience, which encompasses all of these various components, to one single component. In the research presented here, we achieved this using top-down attentional instructions to attend to the sensory component of pain. The previous research on short-term memory of pain also focused mainly on the sensory component of pain. However, within the sensory component of pain the short-term memory of intensity and spatial dimension of pain has been the focus of previous research. Despite its importance, the temporal dimension of pain remained completely unexplored in pain memory research. Thus, the research conducted in this thesis is devoted to the exploration of short-term memory of the duration of pain. Pain duration can be tracked independently, but it can also be tracked conjointly with intensity, such as in dynamic tracking of pain intensity over time. The studies addressed in this thesis examined the isolated processing of pain duration as well as conjoint processing of the duration and intensity of pain. The first psychophysical study explored the nature of the mental representation of the memory template of dynamic thermal pain sensation and, additionally, addressed the differences between the sensory versus affective dimensions of thermal pain sensation in short-term memory. The second psychophysical study focused on properties of the short-term memory of innocuous thermal sensation by comparing dynamic tracking of sensation versus isolated tracking of duration of an innocuous thermal event. The third study explored the dynamic processing of duration conjointly with intensity, versus the isolated processing of duration in short-term memory, using noxious thermal stimuli and functional magnetic resonance imaging (fMRI). Overall, the results of the psychophysical studies showed significant transformation of duration and dynamics information of noxious and innocuous thermal sensation in short-term memory, such as loss of temporal somatosensory information. Additionally, we showed improvement in duration recall during dynamic tracking versus isolated tracking of duration. The fMRI study revealed differences in neural correlates of short-term memory of pain duration versus pain dynamics. Importantly, it also showed striking similarities between neural correlates underlying the short-term memory of pain and those underlying other modalities, such as a contribution of fronto-parietal cortices as well as sensory cortices involved in perceptual processing

Electrophysiological correlates of event segmentation: how does the human mind process ongoing activity?

The human mind decodes, processes, and makes sense of a continual flow of dynamic information, taken from an array of sensory inputs. Compelling behavioural and neuroimaging evidence reveals that humans segment activities into meaningful chunks for processing, and this phenomenon has profound implications for learning, memory and understanding the world around us (Newtson, 1973; Zacks and Tversky, 2001; Zacks et al., 2001). Whilst the existence of event segmentation is widely accepted, it remains unclear what cognitive mechanisms drive this ability.This thesis constitutes a series of behavioural and neuroimaging experiments that investigate top-down and bottom-up influences on event segmentation. The neuroimaging studies presented here are novel; they extend the field by investigating event segmentation using scalp-recorded electroencephalography (EEG). Event Related Potentials (ERPs, derived from EEG using signal-averaging procedures) showed that the perceptual processing of event boundaries is differentially sensitive to the segmentation of activities into small or large chunks, consistent with findings from previous neuroimaging research (Zacks et al., 2001). In contrast with previous findings, the electrophysiological investigations elicited responses that were clearly affected by manipulating top-down information (e.g., participant's knowledge about the activity being segmented). The results from the studies reported in the thesis support an account of the perceptual processing of event boundaries, which incorporates both top-down and bottom-up influences

Biologically Inspired Visual System Architecture for Object Recognition in Autonomous Systems

Findings in recent years on the sensitivity of convolutional neural networks to additive noise, light conditions and to the wholeness of the training dataset, indicate that this technology still lacks the robustness needed for the autonomous robotic industry. In an attempt to bring computer vision algorithms closer to the capabilities of a human operator, the mechanisms of the human visual system was analyzed in this work. Recent studies show that the mechanisms behind the recognition process in the human brain include continuous generation of predictions based on prior knowledge of the world. These predictions enable rapid generation of contextual hypotheses that bias the outcome of the recognition process. This mechanism is especially advantageous in situations of uncertainty, when visual input is ambiguous. In addition, the human visual system continuously updates its knowledge about the world based on the gaps between its prediction and the visual feedback. Convolutional neural networks are feed forward in nature and lack such top-down contextual attenuation mechanisms. As a result, although they process massive amounts of visual information during their operation, the information is not transformed into knowledge that can be used to generate contextual predictions and improve their performance. In this work, an architecture was designed that aims to integrate the concepts behind the top-down prediction and learning processes of the human visual system with the state of the art bottom-up object recognition models, e.g., deep convolutional neural networks. The work focuses on two mechanisms of the human visual system: anticipation-driven perception and reinforcement-driven learning. Imitating these top-down mechanisms, together with the state of the art bottom-up feed-forward algorithms, resulted in an accurate, robust, and continuously improving target recognition model