About this Research Topic
A central question of cognitive neuroscience concerns the role of sensory and motor information in representing conceptual knowledge in the brain. The extent to which conceptual representations are held to be grounded in sensory and motor systems has yielded different hypotheses as to how conceptual knowledge is organized. On the one hand, the embodied hypothesis promotes the idea of conceptual representations that are modality-dependent and built from sensory and motor experiences, i.e. by re-enacting sensorimotor memories acquired through experience (Barsalou, 1999; Pulvermueller, 1999; Barsalou et al., 2003; Gallese & Lakoff, 2005). Thus, recognizing objects, actions and words is accomplished via simulation, i.e. by re-enacting sensorimotor memories acquired through experience. On the opposite extreme, the disembodied hypothesis holds that conceptual representations are abstract (symbolic), modality-independent (amodal), that is to say separated from sensorimotor information (e.g., Fodor, 1983; Caramazza et al., 1990; Tyler & Moss, 2001). To reconcile these two extreme views, the grounding by interaction hypothesis proposes that what we know about the word, for instance, is meant to benefit from the contribution of both abstract content and sensory and motor systems (Mahon & Caramazza, 2008; Bedny & Caramazza, 2011).
From the start, neuropsychological and neuroimaging studies contributed to this debate with the necessary evidence to constrain hypotheses about the role of sensory and motor processes in understanding objects, actions and words. The three theoretical accounts reviewed above generate different predictions as to the involvement of mental simulation in these operations. For the embodied hypothesis, mental simulation appears necessary, however how the brain implements abstract concepts and symbolic operations is still not easily explained within the embodied account. According to the disembodied hypothesis mental simulation is ancillary, whereas the grounding by interaction hypothesis specifies its dependency upon the contextual factors. Even though both the disembodied hypothesis and grounding by interaction hypothesis agree that concepts are stored in an abstract way, a direct demonstration that this actually is the case is seldom documented.
A related aspect that still requires more theoretical and empirical effort concerns the role of implicit motor imagery in understanding words. In fact, despite the growing evidence, results are contradictory: motor activity has been observed not only for bodily actions related verbs but also for imaginable concrete words that are not grounded in sensorimotor experience.
In order to promote the development of the neuroscientific investigation and discussion on how conceptual knowledge is represented, this Frontiers Research Topic aims at bringing together contributions from researchers whose interests focus on the action-related and abstract concepts processing. We are particularly interested in collecting contributions addressing this issue from a neuropsychological perspective. For this Research Topic, we solicit reviews, original research articles, opinion and method papers. Cognitive and behavioral effects of acquired vascular or tumor lesions, of primary dementias, and other neurological diseases impairing cognitive processing will be privileged. In addition, we welcome contributions in which the effects of reversible virtual lesions are studied based on neuropsychological evidence, fMRI experiments on patients, and computational modeling aimed at explaining neuropsychological syndromes.