The Role of Consolidation in Conceptual Memory

Concepts allow us to bring meaning to the world; they require the integration of information from across multiple episodes and events, and the abstraction of statistical patterns and regularities from both new and existing knowledge. Processes during consolidation have been shown to benefit the extraction of gist, the detection of hidden rules and the integration of memory elements into coherent representations. Consolidation may therefore play an important role in the development of conceptual memory. To explore this, we used a range of consolidation delay manipulations and two paradigms that assessed the development of concept-based representations. In Chapter 2 and 3 we used an abstract cross-modal information-integration categorisation task, which allowed us to investigate the integration of information from across modalities (visual and auditory) and the extraction of an underlying category structure. In these experiments we did not find any immediate consolidation benefits on categorisation performance. However, post-consolidation improvements in category learning were observed, if participants had a sleep-filled delay; suggesting that processes during sleep may enhance the effectiveness of future concept-based learning. In Chapters 4 and 5, we used an associative memory task that allowed us to dissociate the impact of consolidation on generalised concept-based representations from trained item knowledge. In this task we found sleep-associated improvements in memory; however, these were specific to trained-item knowledge, with no sleep-associated benefits in measures of memory generalisation. An investigation into intrinsic brain connectivity in Chapter 5 suggests that general variations in functional connectivity can in part explain individual differences in long-term memory performance; with decoupling between heteromodal and sensory-motor brain regions supporting memory generalisation and the formation of concepts. Our results provide new insights into the role of consolidation in the development of conceptual memory and highlight important directions for future research

TheRelationship between brain network organization and variability in episodic memory outcomes and abilities:

Thesis advisor: Maureen RitcheyThesis advisor: Elizabeth KensingerOur brains afford us the remarkable ability to remember past events from our lives, to travel back in time in our minds' eye and relive our memories anew. What are the brain processes that support this ability? In this thesis I investigated this question across three experiments. In Chapter 1, I examined how the brain regions previously linked to episodic cognition (i.e., the hippocampus, parahippocampal cortex, retrosplenial cortex, posterior cingulate cortex, precuneus, angular gyrus, and medial prefrontal cortex) support recollection by building a model that incorporates both region-specific and network-level contributions. I found that these brain regions form ventral and dorsal subnetworks and that their contributions to recollection outcomes are largely explained by subnetwork-level rather than region-specific engagement. In Chapter 2, I used an openly available MRI dataset to test whether individual differences in functional connectivity were related to individual differences in memory ability, finding that network connectivity outside of the classic episodic networks supports individual differences in our ability to remember. In Chapter 3, I tested a neuroscience inspired hypothesis that individuals would have different capacities to bind their memories around social-emotional and visual-spatial content, ultimately finding inconclusive evidence for or against my hypothesis. Together, these results help to solidify our understanding of the brain as an interconnected network of brain regions and shed new light on how these networks support individual differences in memory.Thesis (PhD) — Boston College, 2023.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Psychology

On the Endogenous Generation of Emotion

The thesis investigates the endogenous generation of emotion (EnGE). Two main questions were pursued: 1) How is the volitional generation of emotion neurally and behaviourally implemented? and 2) How can this ability be used for emotional self- regulation? This was investigated in two projects: In the first project, neural, psychophysiological, and behavioural indices of EnGE were investigated in a large, representative sample. The second project investigated the behavioural, functional and structural correlates of meditation practices involving endogenous generation of positive emotion, in a sample of expert meditators. Answering the first question, the first project indicated that EnGE is neurally supported by the cooperation of nodes of the Default Mode (DMN), extended Salience (SN), and left Frontoparietal Control (FPCN) Networks. Results suggest dissociable functional component processes were implemented by these networks, with DMN supporting the generation of simulated representations, while SN supported the generation of core affective qualities of self-generated emotional experiences. FPCN co-activation patterns suggested it supports the coordination of the generation process. The second project showed similar activations during loving-kindness and compassion meditation. Moreover, expert meditators showed increased cortical thickness in, primarily, the left FPCN. This suggests endogenous emotion generation is neurally effected by left FPCN, entraining core affective processes supported by SN and simulation construction supported by DMN. EnGE-based emotional self-regulation was investigated in a second set of studies. Neural and behavioural measures indicated that expert meditators could successfully regulate their emotional reactions to negative external stressors. Comparing compassion with reappraisal-based emotion regulation, regulatory effects differed, with compassion-based regulation primarily increasing positive emotion while reappraisal primarily decreased negative emotion. Moreover, in the large, representative sample, EnGE-abilities were associated with trait affect and emotion management styles. Moreover, evidence was found that EnGE-abilities partially mediate the relationship between positive trait affect and adaptive, instrumental emotion management styles. These results suggest that EnGE can be used in a reactive fashion to regulate emotional reactions to negative stressors, and that EnGE-abilities support emotion management in the normal population.Die vorliegende Arbeit untersucht die endogene Generation von Emotionen (EnGE). Zwei Hauptfragen wurde verfolgt: 1) Wie die willentliche Erzeugung von Emotionen neuronal oder im Verhalten implementiert ist, und 2) wie diese Fähigkeit für die emotionale Selbstregulation verwendet werden kann. Dies wurde in zwei Projekten genauer untersucht: Im ersten Projekt wurden neuronale und psychophysiologische Mechanismen sowie Verhaltensweisen in Bezug auf EnGE in einer großen und repräsentativen Stichprobe untersucht. Das zweite Projekt untersuchte die verhaltensbedingten, funktionellen, und strukturellen Korrelate von bestimmten Meditationsübungen, die die endogene Erzeugung von positiven Emotionen beinhalten, in einer Stichprobe von Meditationsexperten. In Bezug auf die erste Forschungsfrage, haben wir im ersten Projekt Daten erhoben, die nahelegen, dass EnGE auf neuronaler Ebene durch die Kooperation von wichtigen Arealen des Default Mode Netzwerks (DMN), sowie des erweiterten Salience (SN) und des linken Frontoparietal Control (FPCN) Netzwerks unterstützt wird. Ergebnisse legen nahe, dass unterscheidbare funktionelle Komponenten-Prozesse durch diese Netzwerke implementiert werden. Das DMN unterstützt dabei die Erzeugung von simulierten Repräsentationen, während das SN die Generation der „core“ affektive Qualitäten von selbstgenerierten emotionalen Erfahrungen unterstützt. Das FPCN Ko-Aktivierungsmuster legt eine Rolle bei der Koordination von Erzeugungsprozessen nahe. Das zweite Projekt zeigte ähnliche Aktivierungen durch Loving-kindness und Mitgefühls-Meditation. Weiterhin zeigten Meditationsexperten eine erhöhte kortikale Dicke vor allem im linken FPCN. Diese Ergebnisse lassen vermuten, dass eine endogene Emotionsgeneration neuronal vom linken FPCN beeinflusst wird, dass eine SN Aktivierung „core“ affektive Prozesse unterstützt, und dass die Simulationskonstruktion vom DMN gesteuert wird. EnGE-basierte emotionale Selbstregulation wurde mittels dem zweiten Set von Experimenten genauer untersucht. Neuronale- und Verhaltensmaße weisen darauf hin, dass Meditationsexperten ihre eigenen emotionalen Reaktionen auf negative externe Stressoren erfolgreich regulieren konnten. Ein Vergleich von Mitgefühlsmeditation und Neubewertungs- basierter (reappraisal) Emotionsregulation zeigte, dass die Regulationseffekte insofern unterschiedlich sind, dass Mitgefühl-basierte Regulation zunächst positive Emotionen erhöht, während eine Neubewertungsstrategie hauptsächlich negative Emotionen reduziert. Außerdem wurden in der großen und repräsentativen Stichprobe EnGE-Fähigkeiten mit habituellem Affekt (trait affect) und Emotionsmanagement-Stilen assoziiert. EnGE- Fähigkeiten wurden teilweise durch die Beziehung zwischen positiven habituellem Affekt und adaptiven instrumentellen Emotionsmanagement-Stilen vermittelt. Diese Ergebnisse legen nahe, dass EnGE in einer reaktiven Weise für eine Regulation von Emotionsreaktionen auf negative Stressoren verwendet werden kann und das EnGE Fähigkeiten das Emotionsmanagement in einer normalen Population unterstützen

Understanding the behavioral and neurocognitive relation between mind wandering and learning

In the last decade, tremendous advances have been made in the effort to understand mind wandering, yet many questions remain unanswered. Chief among them is how mind wandering relates to learning. Insofar as mind wandering has been linked to poor learning, finding ways to reduce the propensity to mind wander could potentially improve learning. Two experiments were conducted to examine this. The first experiment evaluated how difficulty of the to-be-learned materials affected one’s tendency to mind wander and revealed that people mind wandered when there was a mismatch between their level of expertise and the difficulty of materials studied. The second experiment compared whether participants were more likely to mind wander in blocked or interleaved conditions and showed that participants were more likely to mind wander when materials were presented in a blocked fashion. Together, these results indicate that techniques such as studying materials specific to one’s own level of mastery or changing the way in which one studies might reduce mind wandering and improve learning. Of equal importance is the question of what happens on in the brain when a person mind wanders. While the effect of mind wandering on early sensory processing is known, the impact it has on learning-related processing is not. In two event-related potential (ERP) experiments, participants were asked to report whether they were mind wandering or not while studying materials they were later tested on. Analyses revealed that elaborative semantic processing – indexed by a late, sustained slow wave that was maximal at posterior parietal electrode sites – was attenuated when participants mind wandered. Crucially, the pattern when people were on task rather than mind wandering was similar to the subsequent memory effect previously reported by other memory researchers, suggesting that mind wandering disrupts the deep level of processing required for learning

Oscillations cérébrales et performances cognitives : études à l'état de repos en MEG chez des sujets contrôles et des survivants de cancer pédiatrique

Cette étude s’intéresse au lien entre les dynamiques cérébrales et les capacités cognitives, cette problématique a déjà été explorée auparavant en imagerie cérébrale, notamment à l’aide de tâches effectuées pendant l’imagerie. Cependant la caractérisation de l’activité spontanée a principalement été faite soit avec une faible précision spatiale (capteur EEG/MEG), soit en IRMf qui a une faible résolution temporelle. L’objectif de cette thèse est de caractériser l’activité spontanée au repos au niveau cortical associée à différents processus cognitifs et leur performance. Le second chapitre cherche à établir les corrélats neuronaux de la performance de la mémoire au repos à l’aide des puissances spectrales localisées au niveau des sources corticales. Le troisième chapitre cherche à répliquer les méthodes utilisées dans l’article 1 avec les mêmes participants, mais dans un autre domaine cognitif afin d’établir les corrélats neuronaux de la fluence verbale ainsi que de discriminer une composante verbale et exécutive. Ces deux composantes ont été mises en évidence en utilisant une factorisation avec un test purement exécutif (Trail making test- condition 4) et un autre purement verbal (richesse du vocabulaire). Dans le quatrième chapitre, nous répliquons encore la méthode de l’article 1 avec les mêmes sujets, mais sur un test d’apprentissage verbal. Lors de l’apprentissage verbal, deux stratégies d’apprentissage (sériel et sémantique) possibles sont utilisées de manière concurrente, nous avons cherché à établir si des différences comportementales se traduisaient par des patrons d’activation différents. Dans le cinquième chapitre, nous avons cherché à établir des différences fonctionnelles entre les survivants de la leucémie et des sujets contrôles, puis à établir un lien entre la neurotoxicité et le déficit cognitif rencontré chez cette population, finalement nous avons établi un modèle intégrant neurotoxicité, performance cognitive et marqueur neurophysiologique fonctionnel cérébral. Cette recherche aura approfondi les connaissances sur l’état de repos et principalement fourni les premiers travaux qui mettent en lien l’activité cérébrale spontanée au repos au niveau des sources corticales avec plusieurs tests neuropsychologiques comportementaux. Les résultats ont amené des patrons d’activation spatio-fréquentielle différents, démontrant des spécificités reliées à certains tests comportementaux ou des traitements de l’information (sériel ou sémantique). Finalement les travaux sur les survivants de la leucémie ont montré que l’état de repos pouvait caractériser le fonctionnement des déficits cognitifs à long terme et être un marqueur de remédiation pour de futurs traitements.This study is interested in the link between brain dynamics and cognitive abilities. This problem has already been explored before in brain imaging, notably with the help of task performed during imaging. However, the characterization of spontaneous activity has mainly been done either with weak spatial resolution (EEG/MEG sensor) or in fMRI which has a low temporal resolution. The objective of this thesis is to characterize the spontaneous activity at rest at the cortical level associated with different cognitive processes and their performance. The second chapter seeks to establish the neural correlates of resting memory performance using spectral powers localized at cortical sources. The third chapter seeks to replicate the methods used in article 1 with the same participants but in another cognitive domain in order to establish the neural correlates of verbal fluency as well as to discriminate a verbal and an executive component. These two components were highlighted using a factorization with a purely executive test (Trail making test-condition 4) and another purely verbal one (vocabulary richness). In the fourth chapter, we replicate the method of article 1 with the same subjects, but on a verbal learning test. During verbal learning, two possible learning strategies (serial and semantic) are used concurrently, we sought to establish whether behavioural differences translate into different activation patterns. In the fifth chapter, we sought to establish functional differences between leukemia survivors and control subjects, then to search for a link between neurotoxicity and the cognitive deficit encountered in this population; finally we established a model integrating neurotoxicity, cognitive performance and functional neurophysiological brain markers. This research will have deepened the knowledge on the resting state and mainly provided the first works that link the spontaneous brain activity at rest at the level of cortical sources with several behavioural neuropsychological tests. The results led to different spatio-frequential activation patterns, showing specificities related to certain behavioural tests or information processing (serial or semantic). Finally, work on leukemia survivors has shown that resting states could characterize the functioning of long-term cognitive deficits and be a remediation marker for future treatments

"When We Came There Was Nothing": Land, Work, and Value among Transnational Soybean Farmers in the Brazilian Cerrado

This dissertation is a comparative ethnography of two groups of transnational soybean farmers in the Brazilian Cerrado. In this exploration of migration and industrial crop production for global markets, the new capacity for highly flexible farming is examined in relation to the fixity of family tradition, religious practices, landscapes, and expertise born of working the land. In 1968, Holdeman Mennonites embarked on a tour of rural Brazil. In search of autonomy from an encroaching cultural crisis, they found cheap farm land in Rio Verde, Goiás and encountered a government eager for their migration. Decades later, a group of Midwestern family farmers toured rural Brazil and found cheap, expansive land to occupy. They courted investors (mostly neighboring farmers), bought massive tracts of land, and settled in Luis Eduardo Magalhães, Bahia. The two groups’ migrations began with experiences of crisis: for the Mennonites a cultural crisis in the United States that threatened their family and community reproduction and for the Midwestern family farmers a farm crisis which threatened their livelihoods. In Brazil they adopted common farming techniques related to soil fertilization and tillage, yet differed in crop rotations, use of technology, and most starkly in their perceptions of what counted as “good farming.” Each community internally contested identity and value as they made meaning out of transnational lives and industrial farming. These cases problematize how we understand large-scale processes of the South American soy boom, the massive expansion of soy production in South America, the global land grab, and the proliferation of global land deals. This dissertation identifies difference and generativity of farming in two communities of transnational soybean farmers while also recognizing the power and domination behind such massive economic processes. The Holdeman Mennonite community pursues an alternative to soybean development in their use of family labor, avoidance of capital and technology, and diversified farming practices. The community of Midwestern family farmers adopts capitalist managerial and farming practices, yet reconcile this with their values of good farming. Together they reveal areas of convergence and divergence that make industrial, transnational soybean production possible.Doctor of Philosoph