88 research outputs found

    Linking somatic and symbolic representation in semantic memory: the dynamic multilevel reactivation framework

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    Biological plausibility is an essential constraint for any viable model of semantic memory. Yet, we have only the most rudimentary understanding of how the human brain conducts abstract symbolic transformations that underlie word and object meaning. Neuroscience has evolved a sophisticated arsenal of techniques for elucidating the architecture of conceptual representation. Nevertheless, theoretical convergence remains elusive. Here we describe several contrastive approaches to the organization of semantic knowledge, and in turn we offer our own perspective on two recurring questions in semantic memory research: (1) to what extent are conceptual representations mediated by sensorimotor knowledge (i.e., to what degree is semantic memory embodied)? (2) How might an embodied semantic system represent abstract concepts such as modularity, symbol, or proposition? To address these questions, we review the merits of sensorimotor (i.e., embodied) and amodal (i.e., disembodied) semantic theories and address the neurobiological constraints underlying each. We conclude that the shortcomings of both perspectives in their extreme forms necessitate a hybrid middle ground. We accordingly propose the Dynamic Multilevel Reactivation Framework—an integrative model predicated upon flexible interplay between sensorimotor and amodal symbolic representations mediated by multiple cortical hubs. We discuss applications of the dynamic multilevel reactivation framework to abstract and concrete concept representation and describe how a multidimensional conceptual topography based on emotion, sensation, and magnitude can successfully frame a semantic space containing meanings for both abstract and concrete words. The consideration of ‘abstract conceptual features’ does not diminish the role of logical and/or executive processing in activating, manipulating and using information stored in conceptual representations. Rather, it proposes that the materials upon which these processes operate necessarily combine pure sensorimotor information and higher-order cognitive dimensions involved in symbolic representation

    Spatial relation learning in complementary scenarios with deep neural networks

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    A cognitive agent performing in the real world needs to learn relevant concepts about its environment (e.g., objects, color, and shapes) and react accordingly. In addition to learning the concepts, it needs to learn relations between the concepts, in particular spatial relations between objects. In this paper, we propose three approaches that allow a cognitive agent to learn spatial relations. First, using an embodied model, the agent learns to reach toward an object based on simple instructions involving left-right relations. Since the level of realism and its complexity does not permit large-scale and diverse experiences in this approach, we devise as a second approach a simple visual dataset for geometric feature learning and show that recent reasoning models can learn directional relations in different frames of reference. Yet, embodied and simple simulation approaches together still do not provide sufficient experiences. To close this gap, we thirdly propose utilizing knowledge bases for disembodied spatial relation reasoning. Since the three approaches (i.e., embodied learning, learning from simple visual data, and use of knowledge bases) are complementary, we conceptualize a cognitive architecture that combines these approaches in the context of spatial relation learning

    Learning Actions From Natural Language Instructions Using an ON-World Embodied Cognitive Architecture

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    From Frontiers via Jisc Publications RouterHistory: received 2020-11-05, collection 2021, accepted 2021-04-08, epub 2021-05-13Publication status: PublishedEndowing robots with the ability to view the world the way humans do, to understand natural language and to learn novel semantic meanings when they are deployed in the physical world, is a compelling problem. Another significant aspect is linking language to action, in particular, utterances involving abstract words, in artificial agents. In this work, we propose a novel methodology, using a brain-inspired architecture, to model an appropriate mapping of language with the percept and internal motor representation in humanoid robots. This research presents the first robotic instantiation of a complex architecture based on the Baddeley's Working Memory (WM) model. Our proposed method grants a scalable knowledge representation of verbal and non-verbal signals in the cognitive architecture, which supports incremental open-ended learning. Human spoken utterances about the workspace and the task are combined with the internal knowledge map of the robot to achieve task accomplishment goals. We train the robot to understand instructions involving higher-order (abstract) linguistic concepts of developmental complexity, which cannot be directly hooked in the physical world and are not pre-defined in the robot's static self-representation. Our proposed interactive learning method grants flexible run-time acquisition of novel linguistic forms and real-world information, without training the cognitive model anew. Hence, the robot can adapt to new workspaces that include novel objects and task outcomes. We assess the potential of the proposed methodology in verification experiments with a humanoid robot. The obtained results suggest robust capabilities of the model to link language bi-directionally with the physical environment and solve a variety of manipulation tasks, starting with limited knowledge and gradually learning from the run-time interaction with the tutor, past the pre-trained stage

    Bitter cold, sharp cheese and loud colours : the chromatic cacophony of cross-modal sensory perception

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    This thesis addresses the question of how a consumer's different sensory modalities interact to guide perception and decision-making. Specifically, in three studies, its primary objective is to investigate the cross-modal link between vision (colour) and touch. Colour has a profound influence on human perception. Not only does it cause changes in physiological or emotional states, it can shape what is perceived in other sensory modalities. However, the body of research on these “cross-modal” experiences has predominantly examined colour’s influence on taste and smell. Instead, Study 1 sets out to identify the cross-modal association between vision (colour) and touch (perceived texture of food). Results from Study 1 show colour influences 'perceived' texture of the food during consumption. The extant literature on cross-modal associations involving colour are heavily skewed to situation involving food consumption. To extend existing knowledge, Study 2 applies these cross-modal effects between vision and touch to an advertising setting, where colour is found to influence 'expected' texture. Finally, Study 3 examines the multidirectional nature of the colour-touch relationship, specifically whether touching a product influences perception relating to product colour. Findings from Study 3 demonstrate, under certain conditions, touch does have a cross-modal influence that shapes affective responses to colour cues. Together, the three studies provide further understanding of the cross-modal relationship between vision and touch, and demonstrate the existence of the cross-modal effect in different scenarios and with different products. ACCESS RESTRICTED TO ABSTRACT ONLY UNTIL 12/06/2020

    Applauding with Closed Hands: Neural Signature of Action-Sentence Compatibility Effects

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    BACKGROUND: Behavioral studies have provided evidence for an action-sentence compatibility effect (ACE) that suggests a coupling of motor mechanisms and action-sentence comprehension. When both processes are concurrent, the action sentence primes the actual movement, and simultaneously, the action affects comprehension. The aim of the present study was to investigate brain markers of bidirectional impact of language comprehension and motor processes. METHODOLOGY/PRINCIPAL FINDINGS: Participants listened to sentences describing an action that involved an open hand, a closed hand, or no manual action. Each participant was asked to press a button to indicate his/her understanding of the sentence. Each participant was assigned a hand-shape, either closed or open, which had to be used to activate the button. There were two groups (depending on the assigned hand-shape) and three categories (compatible, incompatible and neutral) defined according to the compatibility between the response and the sentence. ACEs were found in both groups. Brain markers of semantic processing exhibited an N400-like component around the Cz electrode position. This component distinguishes between compatible and incompatible, with a greater negative deflection for incompatible. Motor response elicited a motor potential (MP) and a re-afferent potential (RAP), which are both enhanced in the compatible condition. CONCLUSIONS/SIGNIFICANCE: The present findings provide the first ACE cortical measurements of semantic processing and the motor response. N400-like effects suggest that incompatibility with motor processes interferes in sentence comprehension in a semantic fashion. Modulation of motor potentials (MP and RAP) revealed a multimodal semantic facilitation of the motor response. Both results provide neural evidence of an action-sentence bidirectional relationship. Our results suggest that ACE is not an epiphenomenal post-sentence comprehension process. In contrast, motor-language integration occurring during the verb onset supports a genuine and ongoing brain motor-language interaction

    Practicing phonomimetic (conducting-like) gestures facilitates vocal performance of typically developing children and children with autism: an experimental study

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    Every music teacher is likely to teach one or more children with autism, given that an average of one in 54 persons in the United States receives a diagnosis of Autism Spectrum Disorder (ASD). ASD persons often show tremendous interest in music, and some even become masterful performers; however, the combination of deficits and abilities associated with ASD can pose unique challenges for music teachers. This experimental study shows that phonomimetic (conducting-like) gestures can be used to teach the expressive qualities of music. Children were asked to watch video recordings of conducting-like gestures and produce vocal sounds to match the gestures. The empirical findings indicate that motor training can strengthen the visual to vocomotor couplings in both populations, suggesting that phonomimetic gesture may be a suitable approach for teaching musical expression in inclusive classrooms

    Inner speech and the body error theory

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    Inner speech is commonly understood as the conscious experience of a voice within the mind. One recurrent theme in the scientific literature is that the phenomenon involves a representation of overt speech, for example, a representation of phonetic properties that result from a copy of speech instructions that were ultimately suppressed. I propose a larger picture that involves some embodied objects and their misperception. I call it “the Body Error Theory,” or BET for short. BET is a form of illusionism, but the particular version I favor is a cross-modal illusion. Newly described here, my hypothesis is that the experience of inner speech arises from a mix of interoception and audition. Specifically, there is the detection of slight but well-confirmed activities in the speech musculature that occur during inner speech, which helps to transform representations of normal but quiet nonverbal sounds that inevitably occur during inner speech, from breathing to background noise, into a mistaken perception of inner speech. Simply put, activities in the speech musculature mix with sounds to create the appearance of speech sounds, which thus explains the “voice within the mind.” I also show how BET’s cross-modal system fits with standard information processing accounts for speech monitoring and how it accommodates the central insights of leading theories of inner speech. In addition, I show how BET is supported by data from experience-sampling surveys and how it can be empirically tested against its rivals

    Oscillatory neuronal dynamics during lexical-semantic retrieval and integration

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    Current models of language processing advocate that word meaning is partially stored in distributed modality-specific cortical networks. However, while much has been done to investigate where information is represented in the brain, the neuronal dynamics underlying how these networks communicate internally, and with each other are still poorly understood. For example, it is not clear how spatially distributed semantic content is integrated into a coherent conceptual representation. The current thesis investigates how perceptual semantic features are selected and integrated, using oscillatory neuronal dynamics. Cortical oscillations reflect synchronized activity in large neuronal populations that are associated with specific classes of network interactions. The first part of the present thesis addresses how perceptual semantic features are selected in long-term memory. Using electroencephalographic (EEG) recordings, it is demonstrated that retrieving perceptually more complex information is associated with a reduction in oscillatory power, which is in line with the information via desynchronization hypothesis, a recent neurophysiological model for long-term memory retrieval. The second, and third part address how distributed semantic content is integrated and coordinated in the brain. Behavioral evidence suggests that integrating two features of a target word (e.g., Whistle) during a dual property verification task, incurs an additional processing cost if features are from different (visual: tiny, audio: loud), rather than the same modality (visual: tiny, silver). Furthermore, EEG recordings reveal that integrating cross-modal feature pairs is associated with a more sustained low-frequency theta power increase in the left anterior temporal lobe (ATL). The ATL is thought to converge semantic content from different modalities. In line with this notion, ATL is shown to communicate with a widely distributed cortical network at the theta frequency. The fourth part of the thesis uses magnetoencephalographic (MEG) recordings to show that, while low frequency theta oscillations in left ATL are more sensitive to integrating features from different modalities, integrating two features from the same modality induces an early increase in high frequency gamma power in left ATL and modality-specific regions. These results are in line with a recent framework suggesting that local, and long-range network dynamics are reflected in different oscillatory frequencies. The fifth part demonstrates that the connection weights between left ATL and modality-specific regions at the theta frequency are modulated consistently with the content of the word (e.g., visual features enhance connectivity between left ATL and left inferior occipital cortex). The thesis concludes by embedding these results in the context of current neurocognitive models of semantic processing
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