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The neurobiology of semantic memory

2011; Elsevier BV; Volume: 15; Issue: 11 Linguagem: Inglês

10.1016/j.tics.2011.10.001

1879-307X

Jeffrey R. Binder, Rutvik H. Desai,

Child and Animal Learning Development

Semantic memory includes all acquired knowledge about the world and is the basis for nearly all human activity, yet its neurobiological foundation is only now becoming clear. Recent neuroimaging studies demonstrate two striking results: the participation of modality-specific sensory, motor, and emotion systems in language comprehension, and the existence of large brain regions that participate in comprehension tasks but are not modality-specific. These latter regions, which include the inferior parietal lobe and much of the temporal lobe, lie at convergences of multiple perceptual processing streams. These convergences enable increasingly abstract, supramodal representations of perceptual experience that support a variety of conceptual functions including object recognition, social cognition, language, and the remarkable human capacity to remember the past and imagine the future. Semantic memory includes all acquired knowledge about the world and is the basis for nearly all human activity, yet its neurobiological foundation is only now becoming clear. Recent neuroimaging studies demonstrate two striking results: the participation of modality-specific sensory, motor, and emotion systems in language comprehension, and the existence of large brain regions that participate in comprehension tasks but are not modality-specific. These latter regions, which include the inferior parietal lobe and much of the temporal lobe, lie at convergences of multiple perceptual processing streams. These convergences enable increasingly abstract, supramodal representations of perceptual experience that support a variety of conceptual functions including object recognition, social cognition, language, and the remarkable human capacity to remember the past and imagine the future. in cognitive neuroscience, the general theory that perceptual and motor systems support conceptual knowledge, that is, that understanding or retrieving a concept involves some degree of sensory or motor simulation of the concept. A related term, situated cognition, refers to a more general perspective that emphasizes a central role of perception and action in cognition, rather than memory and memory retrieval. cortex that receives highly processed, multimodal input not dominated by any single modality; also called supramodal, multimodal, or polymodal. information pertaining to a specific modality of experience and processed within the corresponding sensory, motor, or affective system. Modality-specific representations can include primary perceptual or motor information, as well as more complex or abstract representations that are nonetheless modal (e.g., extrastriate visual cortex, parabelt auditory cortex). Modal specificity refers to the representational format of the information. For example, knowledge about the sound a piano makes is modally auditory, whereas knowledge about the appearance of a piano is modally visual, and knowledge of the feeling of playing a piano is modally kinesthetic. Modal representations reflect relevant perceptual dimensions of the input, that is, they are analogs of the input. An auditory representation, for example, captures the spectrotemporal form and loudness of an input, whereas a visual representation codes visual dimensions such as visual form, size and color. an individual's store of knowledge about the world. The content of semantic memory is abstracted from actual experience and is therefore said to be conceptual, that is, generalized and without reference to any specific experience. Memory for specific experiences is called episodic memory, although the content of episodic memory depends heavily on retrieval of conceptual knowledge. Remembering, for example, that one had coffee and eggs for breakfast requires retrieval of the concepts of coffee, eggs and breakfast. Episodic memory might be more properly seen as a particular kind of knowledge manipulation that creates spatial-temporal configurations of object and event concepts. in cognitive neuroscience, the partial re-creation of a perceptual/motor/affective experience or concept through partial reactivation of the neural ensembles originally activated by the experience or concept. Explicit mental imagery may require relatively detailed simulation of a particular experience, whereas tasks such as word comprehension may require only schematic simulations. information that does not pertain to a single modality of experience. Supramodal representations store information about cross-modal conjunctions, such as a particular combination of auditory and visual object attributes. Their existence is sometimes disputed, yet they provide a simple mechanism for a wide range of inferential capacities, such as knowing the visual appearance of a piano given only its sound and knowing about the conceptual similarity structures that define categories. Supramodal representations may also enable the rapid, schematic retrieval of semantic knowledge that characterizes natural language.