To produce a word, the intended word must be selected from a competing set of other words. In other domains where competition affects the selection process, the left inferior frontal gyrus (LIFG) responds to competition among incompatible representations. The aim of this study was to test whether the LIFG is necessary for resolution of competition in word production. Using a methodological approach applying the same rigorous analytic methods to neuropsychological data as is done with neuroimaging data, we compared brain activation patterns in normal speakers (using fMRI) with the results of lesion-deficit correlations in aphasic speakers who performed the same word production task designed to elicit competition during lexical selection. The degree of activation of the LIFG in normal speakers and damage to the LIFG in aphasic speakers was associated with performance on the production task. These convergent findings provide strong support for the hypothesis that the region of cortex commonly known as Broca's area (i.e., the posterior LIFG) serves to bias competitive interactions during language production. aphasia ͉ language production ͉ left inferior frontal gyrus ͉ lexical competition I n 1861, Paul Broca wrote ''somewhere in these [frontal] lobes, one or several convolutions holds under their dependence one of the elements essential to the complex phenomenon of speech.'' In the ensuing century and a half, investigations of the psychological and neural characterization of the ''phenomenon of speech'' have flourished. Here, we unite the principal method of Broca's day, the assessment of the relation between lesion location and cognitive impairments, with the primary human neuroscientific tool of the modern era, functional magnetic resonance imaging (fMRI), in a rigorous evaluation of one putative element of speech: conflict resolution.The need to resolve conflict during speech production is not self-evident; producing speech can feel spontaneous and easy. However, every word produced is susceptible to error. The analysis of speech errors, both the relatively infrequent ones that are made by normal speakers and those that occur with much greater frequency in patients with acquired language disorders, has been a rich source of information about the speech production process. Such analyses have revealed that word selection during production is a naturally competitive process, determined by the relative degree of support for (i.e., activation of) a set of candidate words (1-3). The question addressed in this article is whether a region of the frontal lobes commonly referred to as Broca's area [i.e., the posterior portion of the left inferior frontal gyrus (LIFG)], an area implicated in controlled memory retrieval (4), multiple aspects of language processing (5-8), and competition among linguistic and nonlinguistic representations (9, 10), is necessary for the resolution of conflict among competing lexical representations during word production. We posed this question of both normal and impaired speakers, using a word...

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The nature of the visual representation for words has been fiercely debated for over 150 y. We used direct brain stimulation, pre-and postsurgical behavioral measures, and intracranial electroencephalography to provide support for, and elaborate upon, the visual word form hypothesis. This hypothesis states that activity in the left midfusiform gyrus (lmFG) reflects visually organized information about words and word parts. In patients with electrodes placed directly in their lmFG, we found that disrupting lmFG activity through stimulation, and later surgical resection in one of the patients, led to impaired perception of whole words and letters. Furthermore, using machine-learning methods to analyze the electrophysiological data from these electrodes, we found that information contained in early lmFG activity was consistent with an orthographic similarity space. Finally, the lmFG contributed to at least two distinguishable stages of word processing, an early stage that reflects gist-level visual representation sensitive to orthographic statistics, and a later stage that reflects more precise representation sufficient for the individuation of orthographic word forms. These results provide strong support for the visual word form hypothesis and demonstrate that across time the lmFG is involved in multiple stages of orthographic representation. (1), whereas Wernicke firmly rejected that notion, proposing that reading only necessitates representations of visual letters that feed forward into the language system (2). Similarly, the modern debate revolves around whether there is a visual word form system that becomes specialized for the representation of orthographic knowledge (e.g., the visual forms of letter combinations, morphemes, and whole words) (1, 3, 4). One side of the debate is characterized by the view that the brain possesses a visual word form area that is "a major, reproducible site of orthographic knowledge" (5), whereas the other side disavows any need for reading-specific visual specialization, arguing instead for neurons that are "general purpose analyzers of visual forms" (6).The visual word form hypothesis has attracted great scrutiny because the historical novelty of reading makes it highly unlikely that evolution has created a brain system specialized for reading; this places the analysis of visual word forms in stark contrast to other processes that are thought to have specialized neural systems, such as social, verbal language, or emotional processes, which can be seen in our evolutionary ancestors. Thus, testing the word form hypothesis is critical not only for understanding the neural basis of reading, but also for understanding how the brain organizes information that must be learned through extensive experience and for which we have no evolutionary bias.Advances in neuroimaging and lesion mapping have focused the modern debate surrounding the visual word form hypothesis on the left midfusiform gyrus (lmFG). This focus reflects widespread agreement that the lmFG region plays a critical role ...

While reading is challenging for many deaf individuals, some become proficient readers. Little is known about the component processes that support reading comprehension in these individuals. Speech-based phonological knowledge is one of the strongest predictors of reading comprehension in hearing individuals, yet its role in deaf readers is controversial. This could reflect the highly varied language backgrounds among deaf readers as well as the difficulty of disentangling the relative contribution of phonological versus orthographic knowledge of spoken language, in our case ‘English,’ in this population. Here we assessed the impact of language experience on reading comprehension in deaf readers by recruiting oral deaf individuals, who use spoken English as their primary mode of communication, and deaf native signers of American Sign Language. First, to address the contribution of spoken English phonological knowledge in deaf readers, we present novel tasks that evaluate phonological versus orthographic knowledge. Second, the impact of this knowledge, as well as memory measures that rely differentially on phonological (serial recall) and semantic (free recall) processing, on reading comprehension was evaluated. The best predictor of reading comprehension differed as a function of language experience, with free recall being a better predictor in deaf native signers than in oral deaf. In contrast, the measures of English phonological knowledge, independent of orthographic knowledge, best predicted reading comprehension in oral deaf individuals. These results suggest successful reading strategies differ across deaf readers as a function of their language experience, and highlight a possible alternative route to literacy in deaf native signers.Highlights:1. Deaf individuals vary in their orthographic and phonological knowledge of English as a function of their language experience.2. Reading comprehension was best predicted by different factors in oral deaf and deaf native signers.3. Free recall memory (primacy effect) better predicted reading comprehension in deaf native signers as compared to oral deaf or hearing individuals.4. Language experience should be taken into account when considering cognitive processes that mediate reading in deaf individuals.