Neural Markers of Musical Memory in Young and Older Adults

Memory for music can be preserved in the presence of neurodegenerative disorders even when other memories are forgotten. However, understanding how the brain remembers music has proven difficult despite decades of research. The central goal of this thesis was to elucidate the neural correlates of musical memory by exploring how the presence of language and music information affect the way young and older adults remember music. To that end, I 1) used a controlled training paradigm to familiarize participants with novel stimuli that manipulated the presence of language and music, and 2) collected functional magnetic resonance imaging data to compare brain activity in response to stimuli that were identical except for their level of familiarity. First, I compared differences in neural activation based on familiarity in young adults using general linear model (GLM) and multivariate pattern analyses (Chapter 2). Contrary to the results of previous studies, there were no differences in the areas involved in processing novel and familiar music. Next, I used an intersubject synchrony analysis to assess the effect of familiarity on neural synchrony (Chapters 3 and 5). Synchrony is a new technique in the musical memory literature that correlates neural activation timecourses to a stimulus across individuals. Familiarity reduced synchrony in both young and older adults. Synchrony reduction is associated with increased idiosyncratic processing across participants. This reduction occurred after a single listen suggesting that each participant had a unique experience of the stimuli after only a single exposure. Finally, I used GLM and synchrony analyses together to characterize how musical stimuli with and without language are processed by healthy young and older adults (Chapter 4). Brain areas involved in processing music and language stimuli differed based on age group and stimuli, but in both groups language information induced more synchrony than stimuli without language. Altogether, these results suggest that 1) similarities in stimulus processing across individuals are directly related to the presence of language, and 2) the lack of clearly defined neural correlates of musical memory across previous studies may stem from the idiosyncrasies in processing that arise as individuals become familiar with musical stimuli

The “Narratives” fMRI dataset for evaluating models of naturalistic language comprehension

The “Narratives” collection aggregates a variety of functional MRI datasets collected while human subjects listened to naturalistic spoken stories. The current release includes 345 subjects, 891 functional scans, and 27 diverse stories of varying duration totaling ~4.6 hours of unique stimuli (~43,000 words). This data collection is well-suited for naturalistic neuroimaging analysis, and is intended to serve as a benchmark for models of language and narrative comprehension. We provide standardized MRI data accompanied by rich metadata, preprocessed versions of the data ready for immediate use, and the spoken story stimuli with time-stamped phoneme- and word-level transcripts. All code and data are publicly available with full provenance in keeping with current best practices in transparent and reproducible neuroimaging

Representational dynamics of memories for real-life events

peer reviewedThe continuous flow of experience that characterizes real-life events is not recorded as such in episodic memory but is condensed as a succession of event segments separated by temporal discontinuities. To unravel the neural basis of this representational structure, we recorded real-life events using wearable camera technology and used fMRI to investigate brain activity during their temporal unfolding in memory. We found that, compared to the representation of static scenes in memory, dynamically unfolding memory representations were associated with greater activation of the posterior medial episodic network. Strikingly, by analyzing the autocorrelation of brain activity patterns at successive time points throughout the retrieval period, we found that this network showed higher temporal dynamics when recalling events that included a higher density of event segments. These results reveal the key role of the posterior medial network in representing the dynamic unfolding of the event segments that constitute real-world memories

Release of cognitive and multimodal MRI data including real-world tasks and hippocampal subfield segmentations

We share data from N = 217 healthy adults (mean age 29 years, range 20-41; 109 females, 108 males) who underwent extensive cognitive assessment and neuroimaging to examine the neural basis of individual differences, with a particular focus on a brain structure called the hippocampus. Cognitive data were collected using a wide array of questionnaires, naturalistic tests that examined imagination, autobiographical memory recall and spatial navigation, traditional laboratory-based tests such as recalling word pairs, and comprehensive characterisation of the strategies used to perform the cognitive tests. 3 Tesla MRI data were also acquired and include multi-parameter mapping to examine tissue microstructure, diffusion-weighted MRI, T2-weighted high-resolution partial volume structural MRI scans (with the masks of hippocampal subfields manually segmented from these scans), whole brain resting state functional MRI scans and partial volume high resolution resting state functional MRI scans. This rich dataset will be of value to cognitive and clinical neuroscientists researching individual differences, real-world cognition, brain-behaviour associations, hippocampal subfields and more. All data are freely available on Dryad

Los Argonautas de la Memoria. El trauma social como heterotopía funcional

El siguiente trabajo busca construir una nueva teoría de la memoria y el trauma social resolviendo algunas tensiones teóricas existentes en la literatura especializada. En particular, se propone revisar la relacionada con el debate en torno a la agencia individual o colectiva y la sistematización de la sintomatología traumática. A partir de (re)entender al tiempo y al espacio como fenómenos emergentes argumenta que la memoria por medio del instante hace posible el deseo como potencia y la identidad por medio de la construcción de órdenes simbólicos. En este sentido, se expone una nueva teoría funcional-existencialista afirmando que la memoria es la institución principal de la existencia interpelando a los individuos para volverlos sujetos del existir. Asimismo, se explica como el trauma y la memoria social se unen en un heterotopía que trabaja como un pharmakon, argumentando que el trauma al ser la contracara de la memoria funciona por medio de la lógica del deseo como falta. Por medio de las estructuras clínicas lacanianas se proponen tres psicopatologías sociales traumáticas: la neurosis, la psicosis y la perversión social. Finalmente se realiza un análisis de plausibilidad por medio del estudio del caso de Chile post-pinochetista como ejemplo de una neurosis, el de Rusia post-soviética como el de una psicosis y el de Argentina post- 30’ como el de una perversión socia

Examining the Relationships Between Socio-cognitive Factors and Neural Synchrony During Movie Watching Across Development

While different cognitive abilities mature, the conscious experiences of children likely become richer and more elaborate. A challenge in investigating relationships between cognitive development and real-world experiences is having measures that assess naturalistic processing. Movie watching offers a solution, since following the plot of a film requires cognitive processes that are similar to real-world experiences. When different adults watch the same film, their brain activity begins to align (known as neural synchrony). The strength of this alignment has been shown to reflect the degree to which different individuals are having a similar experience of the movie. While this phenomenon has been established in adults, much less is known about the neural mechanisms supporting naturalistic processing in children and adolescents. The current thesis investigated the neural correlates of movie watching across late childhood and early adolescence. In Chapter 2, I found that autistic children showed more variable brain responses in regions associated with social cognition when watching a movie compared to children without autism. In Chapter 3, I found that adolescents (ages 11-15) with higher cognitive scores showed greater neural synchrony during movie watching in brain regions associated with social processing and executive functions compared to those with below average cognitive scores. This pattern was not evident in children (ages 7-11) who differed in their cognitive scores. In Chapter 4, I found that although the spatial topographies of children’s functional brain networks were nearly indistinguishable during movie watching and rest, these two states differed in the degree of neural synchrony that was present within much of the brain. That is, movies led to significantly more neural synchrony compared to rest, except for in parts of the prefrontal cortex. Taken together, these results suggest that 1) autistic children have more distinct experiences when processing naturalistic stimuli compared to those without autism, 2) adolescents with higher cognitive scores have more similar experiences with each other when watching a movie compared to those with lower scores, and 3) although children’s brain networks during movie watching and rest have a similar functional architecture, processing a film leads to neural synchrony, whereas resting state does not

Learning Naturalistic Temporal Structure in the Posterior Medial Network

The posterior medial network is at the apex of a temporal integration hierarchy in the brain, integrating information over many seconds of viewing intact, but not scrambled, movies. This has been interpreted as an effect of temporal structure. Such structure in movies depends on preexisting event schemas, but temporal structure can also arise de novo from learning. Here, we examined the relative role of schema-consistent temporal structure and arbitrary but consistent temporal structure on the human posterior medial network. We tested whether, with repeated viewing, the network becomes engaged by scrambled movies with temporal structure. Replicating prior studies, activity in posterior medial regions was immediately locked to stimulus structure upon exposure to intact, but not scrambled, movies. However, for temporally structured scrambled movies, functional coupling within the network increased across stimulus repetitions, rising to the level of intact movies. Thus, temporal structure is a key determinant of network dynamics and function in the posterior medial network

Remember the magic? How curiosity elicitation and the availability of extrinsic incentives shape memory formation and its neural mechanisms during encoding and early consolidation

While curiosity – the intrinsic desire to know – is a concept central to the human mind and knowledge acquisition, scientific research targeting the understanding of curiosity is still in its infancy and has only recently begun to unravel it. Studies on information-seeking, a popular way to manipulate and measure curiosity in the lab, found that information shows similar rewarding properties as other, extrinsic rewards/incentives like food or money. Indeed, both can motivate behaviour and elicit a response in the dopaminergic structures of the neural reward circuits. The dopaminergic response further enhances encoding of information that is presented around its release by influencing dopamine-dependent cellular mechanisms of learning in the hippocampus. As such, extrinsic rewards/incentives and curiosity motivate and facilitate learning, illustrating their importance in educational contexts and knowledge acquisition. Taken together, their large overlap in neural response and behavioural effects suggests that both may be supported by common neural processes. However, this implies that their combined use would be associated with sub-additive effects. On the other hand, if both were supported by differential neural effects, they could be used in an additive manner. Importantly, the question of how extrinsic rewards/incentives and curiosity interact in their effects on behaviour and cognition overall and memory in particular can only be answered if both effects are studied in conjunction rather than individually as often done in previous research. Another limitation stems from the way how studies thus far have investigated the effects of curiosity on memory, and in some cases, its interaction with extrinsic rewards/incentives, not only because they nearly exclusively all use the same paradigm, but more so because the paradigm itself has some inherent limitations that might affect how curiosity is conceptualised. The present work tries to address these gaps in the literature. In doing so, a new paradigm – the magic trick paradigm – was developed, in which curiosity and the availability of extrinsic incentives were manipulated to measure their effects on encoding. In the magic trick paradigm, curiosity was elicited using short videos of magic tricks. Participants engaged in an orientation task combined with ratings of the “subjective feelings of curiosity” and performance therein was incentivised using a between-subject design. Unbeknown to the participants, their memory for the magic tricks was tested a week later. Crucially, after behavioural pilots, the paradigm was adopted for usage with functional magnetic resonance imaging (fMRI) to be able to investigate the neural underpinnings of incentive- and/or curiosity-motivated incidental learning during encoding as well as early consolidation. To the best of our knowledge, the associated fMRI dataset – the Magic, Memory, and Curiosity (MMC) Dataset – is the first of its kind, making it highly valuable to the nascent field investigating the effects of curiosity on memory because (1) fMRI data was acquired during the magic trick paradigm, but also before and after, allowing to study neural mechanisms underlying encoding as well as early consolidation, and (2) videos of magic tricks as dynamic stimuli allow for a plethora of analysis approaches to answer myriads of research questions. Chapter 2 describes the methods and procedures used to generate the MMC Dataset (N = 50), presented in a way that allows independent researchers to re-use it according to their needs. Additionally, high data quality comparable to other openly available datasets in the field has been demonstrated by performing data quality assessments and basic validation analysis. This further lays the groundwork for Chapters 3 and 4 where the fMRI data acquired during encoding and consolidation, respectively, will be used. In Chapter 3, a meta-analytical approach was used to analyse the behavioural data from three studies (two behavioural studies and one fMRI study) using the magic trick paradigm to investigate the effects of curiosity, the availability of extrinsic incentives, and their interaction on memory. The main memory outcome was high-confidence recognition, a recollection-based memory measurement, but other indices were also examined to derive a more detailed picture. This revealed positive effects of curiosity and monetary incentives on encoding, in the absence of interaction effects. Exploratory analyses further showed that curiosity and monetary incentives might impact encoding differently, overall suggesting that the effects might be at least partially non-overlapping. Analysing the fMRI data acquired during the presentation of magic tricks using the intersubject synchronisation framework to account for the dynamic nature of the stimuli, we found that while the effects of curiosity on memory were located in the hippocampus and dopaminergic brain areas, neither the effects of curiosity nor incentives themselves were found in the often-implicated reward network, but instead were associated with regions involved in processing uncertainly and attention. Likewise, the effects of curiosity on memory spread further across broad cortical and subcortical networks. Overall, this suggests that the subjective feeling of curiosity and its effects on memory recruits broad brain networks when investigated with dynamic stimuli, caveating a too narrow focus on a small list of regions-of-interest while there is yet so much more to be learned about the effects of curiosity on memory. In Chapter 4, resting-state data acquired before and after learning was used to investigate changes in brain activity at rest following learning. The pre-learning rest data can be used as a baseline, allowing any changes from pre- to post-learning to be attributed to the learning experience itself. Because previous research has repeatedly pointed to similarities between extrinsic rewards/incentives and curiosity, our analysis focused on the change in resting-state functional connectivity between the dopaminergic midbrain and the anterior hippocampus, a dopaminergic consolidation mechanism previously reported in the context of extrinsically motivated learning. Contrary to our hypothesis, we did not find an overall change nor that individual differences therein predicted behavioural measures of learning. However, brain-behaviour correlations differed significantly depending on the availability of extrinsic incentives. In sum, this suggests that curiosity-motivated learning might be supported by different consolidation mechanisms compared to extrinsically motivated learning and that extrinsic motivation could re-configure resting-state networks supporting early consolidation. Overall, this work adds to the literature by replicating the effects of curiosity on encoding. More importantly, however, this work suggests that the systems supporting extrinsically and curiosity-motivated learning might differ more than previously assumed, especially when investigating activity across the whole brain rather than focusing on a priori candidate regions implicated in dopaminergic effects. Indeed, our results allow for the possibility that other neurotransmitter play a role as well in extrinsically and curiosity-motivated learning, further highlighting the need for more research in the area