Thesis (Ph.D.)--Indiana University, Dept. of Psychological and Brain Sciences, 2009. / Title from PDF t.p. (viewed on Feb. 10, 2010). Source: Dissertation Abstracts International, Volume: 70-05, Section: B, page: 3196. Adviser: Luiz Pessoa.

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Thesis (Ph.D.)--Indiana University, Dept. of Psychological and Brain Sciences, 2009. / Title from PDF t.p. (viewed on Jul 22, 2010). Source: Dissertation Abstracts International, Volume: 70-12, Section: B, page: 7873. Adviser: Sharlene Denis Newman.

Thesis (Ph.D.)--York University, 2002. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 63-76). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ99177

Thesis (Ph. D.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 152-163). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

It is now widely accepted that the experience of pain is subject to cognitive influences that may determine the severity of subjectively perceived pain. Many of these top-down factors rely on memory-based processes, which in turn are related to prior experience, learned beliefs and behaviours about pain. As such, memory for pain heavily contributes to the physical pain experience. We posit that pain memory is bidirectional in that following each painful event a trace is stored and that these traces in turn may modify future pain perception prospectively. The following body of work explores aspects of what we have termed a memory template for pain. The results of these chapters taken together, examine these bidirectional aspects of short-term memory for pain employing a recall pain task. Specifically, we explore how, after an acute pain event, a short-term mental representation of the initial event persists. We show that during this time, sensory re-experiencing of the painful event is possible. Furthermore, we investigate aspects of recalled pain, namely intensity and vividness. Data suggests that the intensity and the vividness of this mental representation are determined by the intensity of the initial stimulus, as well as the time-to-test delay. We identify regions that characterise short-term memory for pain. Following on from studies in motor and visual imagery, we explore how pain imagery in the form of recall may affect subsequent pain perception. Our results demonstrate that the inclusion of pain-related imagery preceding physical pain events reduces affective qualities of pain. Testing healthy, naïve subjects, we replicate the effect observed in studies using attention management and imagery strategies, which normally require extensive training. Finally, in a cohort of neuropathic pain patients we show significant reductions in white matter connectivity between areas responsible for working and prospective memory. Collectively, these studies emphasise and elucidate the role of short-term memory of pain in physical pain perception. Acting both retrospectively and prospectively, cognitive reinforcement can increase or decrease the subjective feeling of pain, and therefore manipulating how pain is recalled may have therapeutic potential.

Behaviour is guided by accumulated experience, valuation and comparison. While many aspects associated with these functions are mediated by the frontal lobes, the precise contribution from particular regions remains debated. This thesis will deal with how an organism comes to select an option and will specifically focus on the role of the orbitofrontal cortex (OFC) in two mechanisms in this process: learning of outcome specificities and selecting between multiple options based on their expected values. Despite evidence emphasizing anatomical and connective heterogeneity within this structure, the OFC is often regarded as a uniform region. This thesis aims to resolve some of this uncertainty by assuming that the medial and lateral regions of the OFC contribute differentially to learning and decision-making. Two distinct methodologies were used in these investigations. First, the contribution of the medial OFC to social and emotional processing was examined. The findings from this study disprove previously held beliefs that the medial regions of the OFC guide social and emotional behaviours, but indicted a role for this region in value-guided decision-making. The second study examined functional differences between the lateral and medial OFC by making circumscribed lesions to either region in macaque monkeys. The animals performed a number of 3-armed bandit tasks which were designed to investigate different aspects of value assignment and comparison. The results show that while lateral OFC was required for "credit assignment" – the correct assignment of values to visual cues – medial OFC was critical for comparison of the cues' values during decision-making. In unchanging probabilistic environments, mOFC lesions induced decision-making impairments when value comparison was difficult without affecting credit assignment and associative learning. By contrast, lateral OFC lesions caused the opposite pattern of impairment. The final study used human-neuroimaging techniques to investigate the differential representation of outcome-specific contingency learning and found not only that the expectation of a unique outcome facilitated learning and memory recall but that this was supported by a neural network which included the lateral regions of the OFC and the anterior cingulate cortex. Activity in the mOFC did not correlate with outcome-specific contingency learning but instead reflected both the value associated with the receipt and expectation of a reward. Taken together, the results from this thesis suggest that specific parts of the OFC make markedly different contributions to these very different cognitive functions.

Cette thèse décrit l'intégration multimodale voix-visage pour la perception du genre à l'aide de méthodes comportementales et d'imagerie cérébrale. Dans une première étude psychophysique, les observateurs ont départagé des paires de stimuli voix-visage selon le genre du visage, de la voix ou du stimulus (sans instruction particulière). Une seconde étude a reproduit ce paradigme en ajoutant du bruit visuel et/ou auditif. Conformément à nos résultats théoriques, tâche et bruit peuvent tous deux être modélisés comme des facteurs de pondération. Les deux effets pourraient refléter des changements similaires de hiérarchie fonctionnelle avec la communication par cohérence comme implémentation potentielle de ce mécanisme en termes de modulation sélective de l'information par synchronisation des rythmes d'oscillation neuronaux. Une asymétrie en faveur de la modalité auditive a été trouvée dans les deux études comportementales ainsi que deux interactions : un effet multiplicatif du genre significatif lorsqu'on juge le visage et le stimulus ; un effet de cohérence significatif lorsqu'on juge le visage ou la voix. Une troisième étude en IRMf s'est intéressée aux modulations de connectivité effective entre l'aire fusiforme du visage et l'aire temporale de la voix durant la présentation de stimuli voix-visage en prêtant attention au genre du visage, de la voix ou du stimulus. Une telle modulation a été trouvée dans les tâches du visage et du stimulus en réponse au genre, et dans les tâches du visage et du stimulus en réponse à l'incohérence, deux modulations indépendantes qui pourraient être supportées par l’architecture anatomique en double contre-courant / This thesis describes face-voice multimodal gender integration using complementary behavioral and brain imaging techniques. In a first psychophysical study, observers judged pairs of face-voice stimuli according to face, voice or stimulus (no specific instruction given) gender. A second study tested the bottom-up effect of adding visual and/or auditory noise in the same paradigm. Top-down task and bottom-up noise could both be modeled as weighting effects, as predicted by our theoretical results. Both effects might reflect similar shifts in functional hierarchy. Communication through coherence offers a potential explanation for the neural basis of such a mechanism in terms of selective modulation of segregated cortical streams by oscillatory rhythm synchronization. An asymmetry in favor of the auditory modality was found in both behavioral experiments as well as two interaction effects, first a multiplicative gender effect in the face and stimulus tasks, second an effect of gender coherence in the face and voice tasks. In a third experiment we used fMRI to investigate effective connectivity modulations between the Fusiform Face Area and Temporal Voice Area during the presentation of face-voice stimuli while attending to either face, voice or any gender information. We found a change in effective connectivity for stimulus and face tasks in response to gender information, and for face and voice tasks in response to gender incoherence. These two independent modulations could be supported by the anatomical dual counterstream architecture

L'arithmétique est une des inventions majeures de l'humanité, mais il nous manque encore une compréhension globale de la façon dont le cerveau calcule les additions et soustractions. J'ai utilisé une nouvelle méthode comportementale basée sur un suivi de trajectoire capable de disséquer la succession des étapes de traitement impliquées dans les calculs arithmétiques. Les résultats sont compatibles avec un modèle de déplacement pas à pas sur une ligne numérique mentale, en commençant par l'opérande le plus grand et en ajoutant ou soustrayant de manière incrémentielle l'opérande le plus petit. Ensuite, j'ai analysé les signaux électrophysiologiques enregistrés à partir du cortex humain pendant que les sujets résolvaient des additions. L'activité globale dans le sillon intrapariétal augmentait au fur et à mesure que les opérandes grossissaient, prouvant son implication dans le calcul et la prise de décision. Étonnamment, les sites dans le gyrus temporal inférieur postérieur ont montré que l’activation initiale diminuait en fonction de la taille du problème, suggérant un engagement dans l'identification précoce de la difficulté de calcul. Enfin, j'ai enregistré des signaux de magnétoencéphalographie pendant que les sujets vérifiaient les additions et soustractions. En appliquant des techniques d'apprentissage automatique, j'ai étudié l'évolution temporelle des codes de représentation des opérandes et fourni une première image complète d'une cascade d'étapes de traitement en cours sous-jacentes au calcul arithmétique. Ainsi, cette dissertation fournit-elle plusieurs contributions sur la façon dont les concepts mathématiques élémentaires sont mis en œuvre dans le cerveau. / Arithmetic is one of the most important cultural inventions of humanity, however we still lack a comprehensive understanding of how the brain computes additions and subtractions. In the first study, I used a novel behavioral method based on trajectory tracking capable of dissecting the succession of processing stages involved in arithmetic computations. Results supported a model whereby single-digit arithmetic is computed by a stepwise displacement on a spatially organized mental number line, starting with the larger operand and incrementally adding or subtracting the smaller operand. In a second study, I analyzed electrophysiological signals recorded from the human cortex while subjects solved addition problems. I found that the overall activity in the intraparietal sulcus increased as the operands got larger, providing evidence for its involvement in arithmetic computation and decision-making. Surprisingly, sites within the posterior inferior temporal gyrus showed an initial burst of activity that decreased as a function of problem-size, suggesting an engagement in the early identification of the calculation difficulty. Lastly, I recorded magnetoencephalography signals while subjects verified additions and subtractions. By applying machine learning techniques, I investigated the temporal evolution of the representational codes of the operands and provided a first comprehensive picture of a cascade of unfolding processing stages underlying arithmetic calculation. Overall, this dissertation provides several contributions to our knowledge about how elementary mathematical concepts are implemented in the brain.

Overexpression of the NR2B subunit of the NMDA receptor in the forebrain has been shown to improve learning and memory in mice (Tang et al 1999), which provides exciting implications for the enhancement of human cognition. However, it was first essential to establish replicability, and since the Tang et al (1999) study used only male mice we wished to investigate possible sex differences. On the hidden platform watermaze, we found a trend for male NR2BOE mice to learn the task more quickly than male wildtype mice (as observed by Tang et al. 1999), but the opposite trend in female mice; female NR2BOE mice were slower to reach the hidden platform than female wildtype mice. This pattern of results was also observed on the spatial reference Y memory task and open field task (for anxiety), although not on the spatial working memory T maze task (despite a sex difference). However, wildtype and NR2BOE mice performed at similar levels on the novel object recognition task, the spatial novelty preference task, visible platform watermaze and visual discrimination task. A battery of tests considering some species typical behaviours of mice demonstrated that wildtype and NR2BOE mice were comparable on tests of motor ability, strength, co-ordination, anxiety, burrowing and nesting. This suggests that our behavioural results are not due to a general impairment or enhancement of species typical behaviours. We considered the possibility that the difference between the results of Tang et al (1999) and those we observed may be caused by age differences; hence we attempted to replicate our results on the hidden platform watermaze, spatial reference Y maze and open field test in age matched mice. However, the second cohort of NR2BOE mice performed at similar levels to wildtype mice, and at significantly improved levels compared to the mice of the first cohort. We also considered the effects of knocking out the NR2B subunit on learning and memory, and NR1 subunit deletion within the hippocampus. On the spatial working memory T maze, these mouse strains performed similarly to their respective wildtype strains. Similarly, on a two beacon watermaze (with one indicating the platform position), mice lacking the NR2B subunit were able to locate the platform in a similar length of time. To ensure that the null results we had observed in the second cohort were not due to loss of the NR2B protein overexpression in the forebrain, we performed polymerase chain reactions (PCR), quantitative real-time PCR, and Western blots. We ascertained that the transgene was indeed present and that NR2B mRNA and protein levels were elevated in the hippocampi of the NR2BOE mice. In conclusion, it is unclear why the behaviours we observed in the NR2BOE mice are different to those published in the literature. It is possible that they may be due to differences in environmental enrichment, but the cause of the genotype by sex differences observed in the mice of cohort 1 is unclear. Nonetheless, we have advanced our knowledge of the effects of modifications in the levels of the NR2B subunit of the NMDA receptor on learning and behaviour.