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© 2018 Elsevier Inc. The left angular gyrus has long been implicated in semantic processing. Here we tested whether or not transcranial direct current stimulation (tDCS) over the left angular gyrus modulated reading performance. Adult readers (N = 77) (1) read aloud words that varied in degree of imageability, a semantic word property known to activate the angular gyrus, and (2) completed an N-back task (control task). Individuals were randomly assigned to either the anodal, cathodal or sham stimulation conditions. We found that anodal (p = 0.001) and cathodal (p < 0.001) stimulation impacted how imageability facilitates reading times such that readers who showed the largest imageability effects pre-stimulation showed the greatest reduction in these effects post-stimulation. No effects of stimulation were found in the sham group (p > 0.05) or for the control task (i.e., N-back; p > 0.05). These findings indicate that reading pathways can be modulated via brain stimulation (tDCS) to shift individuals’ sensitivity to word-level characteristics, namely imageability.

Neurolinguistic studies have provided important evidence regarding the organization of lexical representations and the structure of underlying conceptual knowledge; in particular, it has been shown that the retrieval of verbs and nouns can be damaged selectively. Dissociated lexical damage is proof of an independent mental organization of lexical representations and/or of the underlying processes, The aim of the present study is to estimate the rate of dissociated impairments for nouns and verbs on a large sample of mild to moderate aphasic patients and to investigate the mechanisms underlying such phenomena. In addition, the authors wished to verify to what degree the impairment for nouns and verbs is related to a specific type of language disorder. A confrontation naming task for verbs and nouns was administered to 58 aphasic patients. The major lexical (word frequency and age of acquisition) and semantic variables (familiarity and imageability of the underlying concept) were considered for cacti noun and verb used in the task. Verbs were distinguished by major functional classes (transitive, intransitive, and ergative verbs). The data collected from this task were analyzed twice: (i) as a group study comparison of major aphasic subgroups and (ii) as a multiple single case study to evaluate the differences on the naming of verbs and nouns and the effect of the lexical variables on each individual patient. The results confirm the existence of dissociated naming impairments of verbs and nouns. Selective impairment of verbs is more frequent (34%) than that of nouns (10%). In many cases, the dissociated pattern of naming impairment disappeared when the effect of the concomitant variables (word frequency and imageability) was removed, but in approximately one-fifth of the cases the noun or verb superiority was preserved. Noun superiority emerged in five of six agrammatic patients. Both the naming of verbs (n = 9) or of nouns (n = 6) could be impaired selectively in fluent aphasic patients, The results lend support to the hypothesis of an independent mental organization of nouns and verbs, but a substantial effect of imageability and word frequency suggests an interaction of the naming impairment With underlying lexical and semantic aspects. (C) 2002 Elevier Science (USA).