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OBJECTIVE Many neurologically constrained models of semantic memory have been informed by two primary temporal lobe pathologies: Alzheimer's disease (AD) and Semantic Dementia (SD). However, controversy persists regarding the nature of the semantic impairment associated with these patient populations. Some argue that AD presents as a disconnection syndrome(More)
UNLABELLED There are many distinct forms of dementia whose pharmacological and behavioral management differ. Differential diagnosis among the dementia variants currently relies upon a weighted combination of genetic and protein biomarkers, neuroanatomical integrity, and behavior. Diagnostic specificity is complicated by a high degree of overlap in the(More)
Semantic dementia is a neurodegenerative disease characterized by progressive loss of conceptual and lexical knowledge. Cortical atrophy remains relatively isolated to anterior and inferior portions of the temporal lobe early in semantic dementia, later affecting more extensive regions of temporal cortex. Throughout much of the disease course, frontal and(More)
Embodied/modality-specific theories of semantic memory propose that sensorimotor representations play an important role in perception and action. A large body of evidence supports the notion that concepts involving human motor action (i.e., semantic-motor representations) are processed in both language and motor regions of the brain. However, most studies(More)
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Words associated with perceptually salient, highly imageable concepts are learned earlier in life, more accurately recalled, and more rapidly named than abstract words (R. W. Brown, 1976; Walker & Hulme, 1999). Theories accounting for this concreteness effect have focused exclusively on semantic properties of word referents. A novel possibility is that word(More)
Background: Listeners make active use of phonological regularities such as word length to facilitate higher-level syntactic and semantic processing. For example, nouns are longer than verbs, and abstract words are longer than concrete words. Patients with semantic dementia (SD) experience conceptual loss with preserved syntax and phonology. The extent to(More)
Semantic memory refers to our long-term knowledge of word and object meaning. There is increasing evidence that rather than being a passive warehouse of knowledge, semantic memory is a dynamic system whose effectiveness relies on the coordination of multiple components distributed across a large network of cortical regions. Damage to one or more of these(More)
Portions of left inferior frontal cortex have been linked to semantic memory both in terms of the content of conceptual representation (e.g., motor aspects in an embodied semantics framework) and the cognitive processes used to access these representations (e.g., response selection). Progressive non-fluent aphasia (PNFA) is a neurodegenerative condition(More)
Age of acquisition (AoA) is a psycholinguistic construct that refers to the chronological age at which a given word is acquired. Contemporary theories of AoA have focused on lexical acquisition with respect to either the developing phonological or semantic systems. One way of testing the relative dominance of phonological or semantic contributions is(More)