Differences in grammatical or lexical class may not, however, be the principle factor in the neural differentiation between nouns and verbs. As one variable of interest, word meaning, or semantics, has frequently been discussed as an underlying determinant of noun/verb dissociations (Pulvermüller, Lutzenberger et al., 1999, Shallice, 1988, Vigliocco et al., 2011 and Warrington and Shallice, 1984). An essential confound exists in the literature as most verbs are undeniably words used to speak about actions whereas most nouns refer to objects, so it is hardly possible to match and control for relevant semantic differences between check details the lexical classes; furthermore, were one to succeed in precisely

matching sets of nouns and verbs for factors such as the concreteness of their object reference and intensity of their action relationship, one might, from a linguistic perspective, still argue that such selections would certainly be far from representing typical specimens from the lexical groups.

Given this seemingly hopeless confound of lexical Cilengitide order class with semantics, it is therefore unsurprising that many scholars have tried to trace the “lexical” differences to their semantic origins, at least as far as putative word class specific brain activation patterns are concerned. Ingenious attempts have been made to clarify this issue by varying semantic properties within the lexical classes so that consistent noun/verb differences in brain activation – for example in the middle-temporal cortex (Bedny et al. 2008) – reveal more genuine lexical class differences. In addition, many authors have attempted to strip words of their semantics by contrasting homophonous pseudowords in noun and verb context (to wug vs. the wug), thus providing a tool for ascertaining differential representation

of lexical categories (Cappelletti et al., 2008, Laiacona and Caramazza, 2004, Shapiro and Caramazza, 2003, Shapiro et al., 2006 and Shapiro et al., 2001). However, taking on the role of an advocatus diaboli, one might still argue that the phrase “to wug” suggests an action (e.g., whacking) whereas the context “the wug” is more compatible with an object (a rug) interpretation and, therefore, these pseudowords were not truly stripped of semantic associations, but were, in fact, semantically biased by Pyruvate dehydrogenase lipoamide kinase isozyme 1 the contexts in which they were presented: as the authors did not explore this possibility empirically, this interpretation (which has earlier been suggested and supported by Pulvermüller, Kherif, Hauk, Mohr, and Nimmo-Smith (2009) and Vigliocco et al. (2011)) cannot be ruled out at this point. Further evidence for representation of lexical categories in the brain comes from differential brain activity in response to homophonous noun and verb affixes presented in noun and verb contexts ( Pulvermüller & Shtyrov, 2009), which persist even after the contributions of the noun/verb stems are subtracted.