Editorial: The Metaphorical Brain

The Metaphorical Brain Long considered a peripheral topic in linguistics, metaphor is increasingly viewed as a central feature of higher cognition and abstract thought. Investigation of the neural substrate of metaphor has, similarly, become more sophisticated, involving increasingly specific suggestions about the processes involved in its comprehension. This Frontiers Research Topic brings together contributions from a diverse array of cognitive neuroscience to offer a snapshot of current research on the neural substrate of figurative language, and present a number of avenues for future research. The result is an interdisciplinary perspective on the differences between literal and figurative language and how the underlying neurobiological processes can be investigated. Indeed, most investigations into the neural substrate of metaphor ultimately concern the relationship between literal and metaphorical meanings. In their excellent review paper, Vulchanova and colleagues outline the arguments for and against the continuity thesis that literal and metaphorical language comprehension recruits essentially the same processing mechanisms. Using autism as a lens through which to consider the issue, they review data that indicate dissociations in the comprehension of literal and figurative language within individuals with ASD. Ultimately, they suggest figurative language deficits in ASD stem from the difficulty these individuals have integrating contextual information to build the situation model. One source of support for the idea that literal and metaphorical comprehension processes recruit distinct neural substrates is the increasingly contentious claim that the right cerebral hemisphere (RH) plays a crucial role in the comprehension of metaphor, but not literal language. Ianni and colleagues note that much of the data supporting this claim comes from the study of brain-injured patients that have employed sub-optimal tasks for assessing metaphor comprehension. They present a novel test with fine-grained sensitivity to participants' ability to understand both literal and metaphorical language. They present data from three patients to demonstrate (i) comparable impairment on literal and metaphorical language, (ii) greater impairment for metaphorical than literal language, and (iii) selective impairment on metaphorical language. Addressing the issue of hemispheric specialization in healthy adults, Lai and colleagues examine functional neuroimaging data as participants read literal and metaphorical sentences with varying degrees of familiarity. They found that decreasing familiarity (i.e., increasing novelty) of both literal and metaphorical language led to greater activation bilaterally, with more extensive recruitment of LH brain regions overall. However, the relative contribution of the RH was greater for novel metaphors, as a result of reduced LH activation for …