12,640 research outputs found

    Neuronal bases of structural coherence in contemporary dance observation

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    The neuronal processes underlying dance observation have been the focus of an increasing number of brain imaging studies over the past decade. However, the existing literature mainly dealt with effects of motor and visual expertise, whereas the neural and cognitive mechanisms that underlie the interpretation of dance choreographies remained unexplored. Hence, much attention has been given to the Action Observation Network (AON) whereas the role of other potentially relevant neuro-cognitive mechanisms such as mentalizing (theory of mind) or language (narrative comprehension) in dance understanding is yet to be elucidated. We report the results of an fMRI study where the structural coherence of short contemporary dance choreographies was manipulated parametrically using the same taped movement material. Our participants were all trained dancers. The whole-brain analysis argues that the interpretation of structurally coherent dance phrases involves a subpart (Superior Parietal) of the AON as well as mentalizing regions in the dorsomedial Prefrontal Cortex. An ROI analysis based on a similar study using linguistic materials (Pallier et al. 2011) suggests that structural processing in language and dance might share certain neural mechanisms

    The neural bases of event monitoring across domains: a simultaneous ERP-fMRI study.

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    The ability to check and evaluate the environment over time with the aim to detect the occurrence of target stimuli is supported by sustained/tonic as well as transient/phasic control processes, which overall might be referred to as event monitoring. The neural underpinning of sustained control processes involves a fronto-parietal network. However, it has not been well-defined yet whether this cortical circuit acts irrespective of the specific material to be monitored and whether this mediates sustained as well as transient monitoring processes. In the current study, the functional activity of brain during an event monitoring task was investigated and compared between two cognitive domains, whose processing is mediated by differently lateralized areas. Namely, participants were asked to monitor sequences of either faces (supported by right-hemisphere regions) or tools (left-hemisphere). In order to disentangle sustained from transient components of monitoring, a simultaneous EEG-fMRI technique was adopted within a block design. When contrasting monitoring versus control blocks, the conventional fMRI analysis revealed the sustained involvement of bilateral fronto-parietal regions, in both task domains. Event-related potentials (ERPs) showed a more positive amplitude over frontal sites in monitoring compared to control blocks, providing evidence of a transient monitoring component. The joint ERP-fMRI analysis showed that, in the case of face monitoring, these transient processes rely on right-lateralized areas, including the inferior parietal lobule and the middle frontal gyrus. In the case of tools, no fronto-parietal areas correlated with the transient ERP activity, suggesting that in this domain phasic monitoring processes were masked by tonic ones. Overall, the present findings highlight the role of bilateral fronto-parietal regions in sustained monitoring, independently of the specific task requirements, and suggest that right-lateralized areas subtend transient monitoring processes, at least in some task contexts

    The time-course of perceptual decision-making: temporal and spatial dynamics of scalp-recorded oscillatory phase and amplitude

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    Thesis (Ph.D.) - Indiana University, Psychological & Brain Sciences, 2014In natural conditions the brain has to actively integrate information about the current percept with information about past/present behavioral demands and cognitive states of the observer along with future outcomes related to a decision. Despite of somewhat extensive research, we still know little about the neuro-cognitive mechanisms and temporal dynamics allowing an observer to perceive an object and rapidly make a decision about it. This dissertation is based on previous research suggesting that there must be at least two cognitive processes underlying a task such as perceptual decision-making. An early mechanism related to the perception of information and a later one related to the subsequent decision-making process. Evidence has led to the proposal of the match-and-utilization model, stating that early synchronization in the gamma band is the result of a match between the current percept and memory/attentional processes. In contrast, later synchronization would reflect the utilization/readout of the early matching process; updating or influencing future processes. Evidence for this two-stage process, comes mainly from the classic event-related potential literature and, in lesser degree, from newer measures such as oscillatory amplitude. Moreover, the exploration of multivariate nonlinear techniques derived from the study of synchronization between and within neural systems, has been largely neglected in the literature. Thus, explorations of a more complete electrophysiological picture than the one provided by ERP or ERSP analyses alone, can provide us more information about the relation between neural oscillations and ERP components as electrophysiological markers of cognitive events. This is important because differential roles for frequency, phase, and amplitude as different information coding strategies in neural systems have been theoretically suggested and empirically shown. The present work presents for the first time, concomitant analyses of phase and amplitude dynamics in the context of perceptual decision-making. In this dissertation I present a parametrical task that can effectively separate the visual properties of the stimuli from the decision regarding the task at hand. Results indicate that the experimental design effectively separated stimulus properties from task demands. Additionally, I suggest distinct roles for the temporal dynamics of gamma-band oscillations. Finally, a central role for alpha oscillations is suggested

    Idiomatic expressions evoke stronger emotional responses in the brain than literal sentences

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    Recent neuroscientific research shows that metaphors engage readers at the emotional level more strongly than literal expressions. What still remains unclear is what makes metaphors more engaging, and whether this generalises to all figurative expressions, no matter how conventionalised they are. This fMRI study aimed to investigate whether idiomatic expressions - the least creative part of figurative language - indeed trigger a higher affective resonance than literal expressions, and to explore possible interactions between activation in emotion-relevant neural structures and regions associated with figurative language processing. Participants silently read for comprehension a set of emotionally positive, negative and neutral idioms embedded in short sentences, and similarly valenced literal sentences. As in studies on metaphors, we found enhanced activation of the left inferior frontal gyrus and left amygdala in response to idioms, indexing stronger recruitment of executive control functions and enhanced emotional engagement, respectively. This suggests that the comprehension of even highly conventionalised and familiar figurative expressions, namely idioms, recruits regions involved in emotional processing. Furthermore, increased activation of the IFG interacted positively with activation in the amygdala, suggesting that the stronger cognitive engagement driven by idioms may in turn be coupled with stronger involvement at the emotional level

    The emotion potential of words and passages in reading Harry Potter:an fMRI study

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    Previous studies suggested that the emotional connotation of single words automatically recruits attention. We investigated the potential of words to induce emotional engagement when reading texts. In an fMRI experiment, we presented 120 text passages from the Harry Potter book series. Results showed significant correlations between affective word (lexical) ratings and passage ratings. Furthermore, affective lexical ratings correlated with activity in regions associated with emotion, situation model building, multi-modal semantic integration, and Theory of Mind. We distinguished differential influences of affective lexical, inter-lexical, and supra-lexical variables: differential effects of lexical valence were significant in the left amygdala, while effects of arousal-span (the dynamic range of arousal across a passage) were significant in the left amygdala and insula. However, we found no differential effect of passage ratings in emotion-associated regions. Our results support the hypothesis that the emotion potential of short texts can be predicted by lexical and inter-lexical affective variables

    Food knowledge depends upon the integrity of both sensory and functional properties: a VBM, TBSS and DTI tractography study

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    Food constitutes a fuel of life for human beings. It is therefore of chief importance that their recognition system readily identifies the most relevant properties of food by drawing on semantic memory. One of the most relevant properties to be considered is the level of processing impressed by humans on food. We hypothesized that recognition of raw food capitalizes on sensory properties and that of transformed food on functional properties, consistently with the hypothesis of a sensory-functional organization of semantic knowledge. To test this hypothesis, patients with Alzheimer's disease, frontotemporal dementia, primary progressive aphasia, and healthy controls performed lexical-semantic tasks with food (raw and transformed) and non-food (living and nonliving) stimuli. Correlations between task performance and local grey matter concentration (VBM) and white matter fractional anisotropy (TBSS) led to two main findings. First, recognition of raw food and living things implicated occipital cortices, typically involved in processing sensory information and, second, recognition of processed food and nonliving things implicated the middle temporal gyrus and surrounding white matter tracts, regions that have been associated with functional properties. In conclusion, the present study confirms and extends the hypothesis of a sensory and a functional organization of semantic knowledge

    Population Parameters of Intermediate-Age Star Clusters in the Large Magellanic Cloud. I. NGC 1846 and its Wide Main Sequence Turnoff

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    The Advanced Camera for Surveys on board the Hubble Space Telescope has been used to obtain deep, high-resolution images of the intermediate-age star cluster NGC 1846 in the Large Magellanic Cloud. We present new color-magnitude diagrams (CMDs) based on F435W, F555W, and F814W imaging. We test the previously observed broad main sequence turnoff region for "contamination" by field stars and (evolved) binary star systems. We find that while these impact the number of objects in this region, none can fully account for the large color spread. Our results therefore solidify the recent finding that stars in the main sequence turnoff region of this cluster have a large spread in color which is unrelated to measurement errors or contamination by field stars, and likely due to a ~300 Myr range in the ages of cluster stars. An unbiased estimate of the stellar density distribution across the main sequence turnoff region shows that the spread is fairly continuous rather than strongly bimodal as suggested previously. We fit the CMDs with several different sets of theoretical isochrones, and determine systematic uncertainties for population parameters when derived using any one set of isochrones. We note a degeneracy between age and [alpha/Fe], which can be lifted by matching the shape (curvature) of the full red giant branch in the CMD. We find that stars in the upper part of the main sequence turnoff region are more centrally concentrated than those in any other region of the CMD, including more massive red giant branch and asymptotic giant branch stars. We consider several possible formation scenarios which account for the unusual features observed in the CMD of NGC 1846.Comment: 17 pages, 17 figures, in emulateapj format. Figures 1 and 2 have been downgraded in resolution in this version. Accepted for publication in The Astronomical Journa

    A Free-Form Lensing Grid Solution for A1689 with New Mutiple Images

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    Hubble Space Telescope imaging of the galaxy cluster Abell 1689 has revealed an exceptional number of strongly lensed multiply-imaged galaxies, including high-redshift candidates. Previous studies have used this data to obtain the most detailed dark matter reconstructions of any galaxy cluster to date, resolving substructures ~25 kpc across. We examine Abell 1689 (hereafter, A1689) non-parametrically, combining strongly lensed images and weak distortions from wider field Subaru imaging, and we incorporate member galaxies to improve the lens solution. Strongly lensed galaxies are often locally affected by member galaxies, however, these perturbations cannot be recovered in grid based reconstructions because the lensing information is too sparse to resolve member galaxies. By adding luminosity-scaled member galaxy deflections to our smooth grid we can derive meaningful solutions with sufficient accuracy to permit the identification of our own strongly lensed images, so our model becomes self consistent. We identify 11 new multiply lensed system candidates and clarify previously ambiguous cases, in the deepest optical and NIR data to date from Hubble and Subaru. Our improved spatial resolution brings up new features not seen when the weak and strong lensing effects are used separately, including clumps and filamentary dark matter around the main halo. Our treatment means we can obtain an objective mass ratio between the cluster and galaxy components, for examining the extent of tidal stripping of the luminous member galaxies. We find a typical mass-to-light ratios of M/L_B = 21 inside the r<1 arcminute region that drops to M/L_B = 17 inside the r<40 arcsecond region. Our model independence means we can objectively evaluate the competitiveness of stacking cluster lenses for defining the geometric lensing-distance-redshift relation in a model independent way.Comment: 23 pages with 25 figures Replced with MNRAS submitted version. Some figures have been corrected and minor text edit

    Shades Of Meaning: Capturing Meaningful Context-Based Variations In Neural Patterns

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    When cognitive psychologists and psycholinguists consider the variability that arises during the retrieval of conceptual information, this variability it is often understood to arise from the dynamic interactions between concepts and contexts. �When cognitive neuroscientists and neurolinguists think about this variability, it is typically treated as noise and discarded from the analyses. In this dissertation, we bridge these two traditions by asking: can the variability in neural patterns evoked by word meanings reflect the contextual variation that occurs during conceptual processing? We employ functional magnetic resonance imaging (fMRI) to measure, quantify, and predict brain activity during context-dependent retrieval of word meanings. Across three experiments, we test the ways in which word-evoked neural variability is influenced by the sentence context in which the word appears (Chapter 2); the current set of task demands (Chapter 3); or even undirected thoughts about other concepts (Chapter 4). Our findings indicate that not only do the neural patterns evoked by the same stimulus word vary over time, but we can predict the degree to which these patterns vary using meaningful, theoretically motivated variables. These results demonstrate that cross-context, within-concept variations in neural responses are not exclusively due to statistical noise or measurement error. Rather, the degree of a concept’s neural variability varies in a manner that accords with a context-dependent view of semantic representation. In addition, we present preliminary evidence that prefrontally-mediated cognitive control processes are involved in expression of context-appropriate neural patterns. In sum, these studies provide a novel perspective on the flexibility of word meanings and the variable brain activity patterns associated with them
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