32 research outputs found

    Sensory contribution to vocal emotion deficit in patients with cerebellar stroke

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    In recent years, there has been increasing evidence of cerebellar involvement in emotion processing. Difficulties in the recognition of emotion from voices (i.e., emotional prosody) have been observed following cerebellar stroke. However, the interplay between sensory and higher-order cognitive dysfunction in these deficits, as well as possible hemispheric specialization for emotional prosody processing, has yet to be elucidated. We investigated the emotional prosody recognition performances of patients with right versus left cerebellar lesions, as well as of matched controls, entering the acoustic features of the stimuli in our statistical model. We also explored the cerebellar lesion-behavior relationship, using voxel-based lesion-symptom mapping. Results revealed impairment of vocal emotion recognition in both patient subgroups, particularly for neutral or negative prosody, with a higher number of misattributions in patients with right-hemispheric stroke. Voxel-based lesion-symptom mapping showed that some emotional misattributions correlated with lesions in the right Lobules VIIb and VIII and right Crus I and II. Furthermore, a significant proportion of the variance in this misattribution was explained by acoustic features such as pitch, loudness, and spectral aspects. These results point to bilateral posterior cerebellar involvement in both the sensory and cognitive processing of emotions

    Mapping the Spatiotemporal Evolution of Emotional Processing: An MEG Study Across Arousal and Valence Dimensions

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    Electrophysiological and functional neuroimaging findings indicate that the neural mechanisms underlying the processing of emotional dimensions (i.e., valence, arousal) constitute a spatially and temporally distributed emotional network, modulated by the arousal and/or valence of the emotional stimuli. We examined the time course and source distribution of gamma time-locked magnetoencephalographic activity in response to a series of emotional stimuli viewed by healthy adults. We used a beamformer and a sliding window analysis to generate a succession of spatial maps of event-related brain responses across distinct levels of valence (pleasant/unpleasant) and arousal (high/low) in 30–100 Hz. Our results show parallel emotion-related responses along specific temporal windows involving mainly dissociable neural pathways for valence and arousal during emotional picture processing. Pleasant valence was localized in the left inferior frontal gyrus, while unpleasant valence in the right occipital gyrus, the precuneus, and the left caudate nucleus. High arousal was processed by the left orbitofrontal cortex, amygdala, and inferior frontal gyrus, as well as the right middle temporal gyrus, inferior parietal lobule, and occipital gyrus. Pleasant by high arousal interaction was localized in the left inferior and superior frontal gyrus, as well as the right caudate nucleus, putamen, and gyrus rectus. Unpleasant by high arousal interaction was processed by the right superior parietal gyrus. Valence was prioritized (onset at ∼60 ms) to all other effects, while pleasant valence was short lived in comparison to unpleasant valence (offsets at ∼110 and ∼320 ms, respectively). Both arousal and valence × arousal interactions emerged relatively early (onset at ∼150 ms, and ∼170 ms, respectively). Our findings support the notion that brain regions differentiate between valence and arousal, and demonstrate, for the first time, that these brain regions may also respond to distinct combinations of these two dimensions within specific time windows

    Resting-State Functional Connectivity and Network Analysis of Cerebellum with Respect to Crystallized IQ and Gender

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    During the last years, it has been established that the prefrontal and posterior parietal brain lobes, which are mostly related to intelligence, have many connections to cerebellum. However, there is a limited research investigating cerebellum's relationship with cognitive processes. In this study, the network of cerebellum was analyzed in order to investigate its overall organization in individuals with low and high crystallized Intelligence Quotient (IQ). Functional magnetic resonance imaging (fMRI) data were selected from 136 subjects in resting-state from the Human Connectome Project (HCP) database and were further separated into two IQ groups composed of 69 low-IQ and 67 high-IQ subjects. Cerebellum was parcellated into 28 lobules/ROIs (per subject) using a standard cerebellum anatomical atlas. Thereafter, correlation matrices were constructed by computing Pearson's correlation coefficients between the average BOLD time-series for each pair of ROIs inside the cerebellum. By computing conventional graph metrics, small-world network properties were verified using the weighted clustering coefficient and the characteristic path length for estimating the trade-off between segregation and integration. In addition, a connectivity metric was computed for extracting the average cost per network. The concept of the Minimum Spanning Tree (MST) was adopted and implemented in order to avoid methodological biases in graph comparisons and retain only the strongest connections per network. Subsequently, six global and three local metrics were calculated in order to retrieve useful features concerning the characteristics of each MST. Moreover, the local metrics of degree and betweenness centrality were used to detect hubs, i.e., nodes with high importance. The computed set of metrics gave rise to extensive statistical analysis in order to examine differences between low and high-IQ groups, as well as between all possible gender-based group combinations. Our results reveal that both male and female networks have small-world properties with differences in females (especially in higher IQ females) indicative of higher neural efficiency in cerebellum. There is a trend toward the same direction in men, but without significant differences. Finally, three lobules showed maximum correlation with the median response time in low-IQ individuals, implying that there is an increased effort dedicated locally by this population in cognitive tasks

    The Neuroscience of Positive Emotions and Affect:Implications for Cultivating Happiness and Wellbeing

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    This review paper provides an integrative account regarding neurophysiological correlates of positive emotions and affect that cumulatively contribute to the scaffolding for happiness and wellbeing in humans and other animals. This paper reviews the associations among neurotransmitters, hormones, brain networks, and cognitive functions in the context of positive emotions and affect. Consideration of lifespan developmental perspectives are incorporated, and we also examine the impact of healthy social relationships and environmental contexts on the modulation of positive emotions and affect. The neurophysiological processes that implement positive emotions are dynamic and modifiable, and meditative practices as well as flow states that change patterns of brain function and ultimately support wellbeing are also discussed. This review is part of "The Human Affectome Project" (http://neuroqualia.org/background.php), and in order to advance a primary aim of the Human Affectome Project, we also reviewed relevant linguistic dimensions and terminology that characterizes positive emotions and wellbeing. These linguistic dimensions are discussed within the context of the neuroscience literature with the overarching goal of generating novel recommendations for advancing neuroscience research on positive emotions and wellbeing

    Physiology and neuroanatomy of emotional reactivity in frontotemporal dementia

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    ABSTRACT AND SUMMARY OF EXPERIMENTAL FINDINGS The frontotemporal dementias (FTD) are a heterogeneous group of neurodegenerative diseases that cause variable profiles of fronto-insulo-temporal network disintegration. Loss of empathy and dysfunctional social interaction are a leading features of FTD and major determinants of care burden, but remain poorly understood and difficult to measure with conventional neuropsychological instruments. Building on a large body of work in the healthy brain showing that embodied responses are important components of emotional responses and empathy, I performed a series of experiments to examine the extent to which the induction and decoding of somatic physiological responses to the emotions of others are degraded in FTD, and to define the underlying neuroanatomical changes responsible for these deficits. I systematically studied a range of modalities across the entire syndromic spectrum of FTD, including daily life emotional sensitivity, the cognitive categorisation of emotions, interoceptive accuracy, automatic facial mimicry, autonomic responses, and structural and functional neuroanatomy to deconstruct aberrant emotional reactivity in these diseases. My results provide proof of principle for the utility of physiological measures in deconstructing complex socioemotional symptoms and suggest that these warrant further investigation as clinical biomarkers in FTD. Chapter 3: Using a heartbeat counting task, I found that interoceptive accuracy is impaired in semantic variant primary progressive aphasia, but correlates with sensitivity to the emotions of others across FTD syndromes. Voxel based morphometry demonstrated that impaired interoceptive accuracy correlates with grey matter volume in anterior cingulate, insula and amygdala. Chapter 4: Using facial electromyography to index automatic imitation, I showed that mimicry of emotional facial expressions is impaired in the behavioural and right temporal variants of FTD. Automatic imitation predicted correct identification of facial emotions in healthy controls and syndromes focussed on the frontal lobes and insula, but not in syndromes focussed on the temporal lobes, suggesting that automatic imitation aids emotion recognition only when social concepts and semantic stores are intact. Voxel based morphometry replicated previously identified neuroanatomical correlates of emotion identification ability, while automatic imitation was associated with grey matter volume in a visuomotor network including primary visual and motor cortices, visual motion area (MT/V5) and supplementary motor cortex. Chapter 5: By recording heart rate during viewing of facial emotions, I showed that the normal cardiac reactivity to emotion is impaired in FTD syndromes with fronto-insular atrophy (behavioural variant FTD and nonfluent variant primary progressive aphasia) but not in syndromes focussed on the temporal lobes (right temporal variant FTD and semantic variant primary progressive aphasia). Unlike automatic imitation, cardiac reactivity dissociated from emotion identification ability. Voxel based morphometry revealed grey matter correlates of cardiac reactivity in anterior cingulate, insula and orbitofrontal cortex. Chapter 6: Subjects viewed videos of facial emotions during fMRI scanning, with concomitant recording of heart rate and pupil size. I identified syndromic profiles of reduced activity in posterior face responsive regions including posterior superior temporal sulcus and fusiform face area. Emotion identification ability was predicted by activity in more anterior areas including anterior cingulate, insula, inferior frontal gyrus and temporal pole. Autonomic reactivity related to activity in both components of the central autonomic control network and regions responsible for processing the sensory properties of the stimuli

    Time Distortions in Mind

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    Time Distortions in Mind brings together current research on temporal processing in clinical populations to elucidate the interdependence between perturbations in timing and disturbances in the mind and brain. For the student, the scientist, and the stepping-stone for further research

    Time Distortions in Mind

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    Time Distortions in Mind brings together current research on temporal processing in clinical populations to elucidate the interdependence between perturbations in timing and disturbances in the mind and brain. For the student, the scientist, and the stepping-stone for further research. Readership: An excellent reference for the student and the scientist interested in aspects of temporal processing and abnormal psychology

    The neural basis of semantic processing across comprehension contexts

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    Current neurobiological models of semantic cognition have been predominately derived from studies of single-words or sentences which may provide an impoverished estimate of how semantic processing occurs in real-world contexts. Studies that make use of more ecologically valid stimuli such as natural language or narratives suggest that, counter to the hub-and-spoke framework in which the anterior temporal lobe (ATL) serves as a graded hub integrating information from proximal sensorimotor spokes, the semantic system displays voxel-wise category specialization tiled across a large, distributed network. A complicating factor in reconciling these seemingly conflicting claims is the over-reliance on concrete conceptual knowledge in describing the organization of the semantic system. A recent theoretical account argues that social knowledge, like other types of semantic knowledge, is processed within the ventrolateral ATL, but this claim has not been tested using naturalistic stimuli, which better sample abstract social knowledge, including pragmatic inference. This thesis investigates the organization of the semantic system across multiple scales, from isolated words to multimodal narratives, and across multiple types of semantic conceptual knowledge, from concrete to abstract. Using comprehension of concrete words as a starting point, the first study describes a critical examination of specialization within the semantic system for taxonomic (dog – bear) and thematic (dog – leash) relations using intracranial EEG recordings from an array of depth electrodes within ATL, inferior parietal lobule (IPL), and two regions within the semantic control network, inferior frontal gyrus (IFG) and posterior middle temporal gyrus (pMTG). Moving across the context and conceptual scale to build upon this work, the second study investigated how the concrete and abstract lexical and semantic properties of single-words, akin to those that informed the hub-and-spoke model, are processed in a complex, complete narrative presented to participants during fMRI scanning. In doing so, this study enabled comparisons between prior studies of isolated words and naturalistic work, thus moving toward an integrated cross-scale account of semantic cognition. Using the same neuroimaging data, the third study extended this work to investigate how context contributes to the construction of meaning by studying how the semantic and social cognitive systems are engaged by social and pragmatic sentence-level content. This enabled a direct, naturalistic test of the claim that social knowledge is housed within the semantic system. The fourth study investigated shared processing between social and semantic systems using fMRI data collected during movie-viewing, which captures the multimodal environment in which social knowledge is exchanged. The results of these studies collectively demonstrate that the semantic and social systems are differentially engaged across the scales investigated here. Concrete conceptual relations engage one (or more) specialized hubs within the semantic system, whereas processing of naturalistic verbal and event content co-varies with activation in large brain networks. There is evidence of functional gradations within ATL that are differentially sensitive to the demands of narrative comprehension – the anterior superior temporal gyrus (i.e., dorsolateral subregion) and anterior fusiform (i.e., ventral subregion) appear to be particularly sensitive to the quantity and informativeness of external input whereas the anterior middle and inferior temporal gyri (i.e., ventrolateral subregion) appear to be engaged by internal, or endogenous, semantic processing during narrative comprehension. Engagement of this same ventrolateral subregion is observed in response to social word and sentence content, providing support for the claim that social processing is subsumed within the semantic system. Taken together, the results suggest an extension to the current neurobiological model of semantic cognition that accommodates comprehension contexts. The studies undertaken as part of this thesis build upon the existing concept-level frameworks towards a narrative-level framework of semantic cognition
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