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Word-production theories argue that during language production, a concept activates multiple lexical candidates in left temporal cortex, and the intended word is selected from this set. Evidence for theories on spoken-word production comes, for example, from the picture-word interference task, where participants name pictures superimposed by congruent (e.g., picture: rabbit, distractor "rabbit"), categorically related (e.g., distractor "sheep"), or unrelated (e.g., distractor "fork") words. Typically, whereas congruent distractors facilitate naming, related distractors slow down picture naming relative to unrelated distractors, resulting in semantic interference. However, the neural correlates of semantic interference are debated. Previous neuroimaging studies have shown that the left mid-to-posterior STG (pSTG) is involved in the interference associated with semantically related distractors. To probe the functional relevance of this area, we targeted the left pSTG with focal repetitive transcranial magnetic stimulation (rTMS) while subjects performed a picture-word interference task. Unexpectedly, pSTG stimulation did not affect the semantic interference effect but selectively increased the congruency effect (i.e., faster naming with congruent distractors). The facilitatory TMS effect selectively occurred in the more difficult list with an overall lower name agreement. Our study adds new evidence to the causal role of the left pSTG in the interaction between picture and distractor representations or processing streams, only partly supporting previous neuroimaging studies. Moreover, the observed unexpected condition-specific facilitatory rTMS effect argues for an interaction of the task- or stimulus-induced brain state with the modulatory TMS effect. These issues should be systematically addressed in future rTMS studies on language production., Competing Interests: The authors have declared that no competing interests exist.

Flexible language use requires coordinated functioning of two systems: conceptual representations and control. The interaction between the two systems can be observed when people are asked to match a word to a picture. Participants are slower and less accurate for related word-picture pairs (word: banana, picture: apple) relative to unrelated pairs (word: banjo, picture: apple). The mechanism underlying interference however is still unclear. We analyzed word-picture matching (WPM) performance of patients with stroke-induced lesions to the left-temporal (N = 5) or left-frontal cortex (N = 5) and matched controls (N = 12) using the drift diffusion model (DDM). In DDM, the process of making a decision is described as the stochastic accumulation of evidence towards a response. The parameters of the DDM model that characterize this process are decision threshold, drift rate, starting point and non-decision time, each of which bears cognitive interpretability. We compared the estimated model parameters from controls and patients to investigate the mechanisms of WPM interference. WPM performance in controls was explained by the amount of information needed to make a decision (decision threshold): a higher threshold was associated with related word-picture pairs relative to unrelated ones. No difference was found in the quality of the evidence (drift rate). This suggests an executive rather than semantic mechanism underlying WPM interference. Both patients with temporal and frontal lesions exhibited both increased drift rate and decision threshold for unrelated pairs relative to related ones. Left-frontal and temporal damage affected the computations required by WPM similarly, resulting in systematic deficits across lexical-semantic memory and executive functions. These results support a diverse but interactive role of lexical-semantic memory and semantic control mechanisms., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

While much progress has been made in how brain organization supports language function, the language network's ability to adapt to immediate disturbances by means of reorganization remains unclear. The aim of this study was to examine acute reorganizational changes in brain activity related to conceptual and lexical retrieval in unimpaired language production following transient disruption of the left middle temporal gyrus (MTG). In a randomized single-blind within-subject experiment, we recorded the electroencephalogram from 16 healthy participants during a context-driven picture-naming task. Prior to the task, the left MTG was perturbed with real continuous theta-burst stimulation (cTBS) or sham stimulation. During the task, participants read lead-in sentences creating a constraining (e.g., "The farmer milks the") or nonconstraining context (e.g., "The farmer buys the"). The last word was shown as a picture that participants had to name (e.g., "cow"). Replicating behavioral studies, participants were overall faster in naming pictures following a constraining relative to a nonconstraining context, but this effect did not differ between real and sham cTBS. In contrast, real cTBS increased overall error rates compared to sham cTBS. In line with previous studies, we observed a decrease in alpha-beta (8-24 Hz) oscillatory power for constraining relative to nonconstraining contexts over left temporal-parietal cortex after participants received sham cTBS. However, following real cTBS, this decrease extended toward left prefrontal regions associated with both domain-general and domain-specific control mechanisms. Our findings provide evidence that immediately after perturbing the left MTG, the lexical-semantic network is able to quickly reconfigure, also recruiting domain-general regions., (© 2019 The Authors. Human Brain Mapping published by Wiley Periodicals, Inc.)

Different frequency bands in the electroencephalogram are postulated to support distinct language functions. Studies have suggested that alpha-beta power decreases may index word-retrieval processes. In context-driven word retrieval, participants hear lead-in sentences that either constrain the final word ('He locked the door with the') or not ('She walked in here with the'). The last word is shown as a picture to be named. Previous studies have consistently found alpha-beta power decreases prior to picture onset for constrained relative to unconstrained sentences, localised to the left lateral-temporal and lateral-frontal lobes. However, the relative contribution of temporal versus frontal areas to alpha-beta power decreases is unknown. We recorded the electroencephalogram from patients with stroke lesions encompassing the left lateral-temporal and inferior-parietal regions or left-lateral frontal lobe and from matched controls. Individual participant analyses revealed a behavioural sentence context facilitation effect in all participants, except for in the two patients with extensive lesions to temporal and inferior parietal lobes. We replicated the alpha-beta power decreases prior to picture onset in all participants, except for in the two same patients with extensive posterior lesions. Thus, whereas posterior lesions eliminated the behavioural and oscillatory context effect, frontal lesions did not. Hierarchical clustering analyses of all patients' lesion profiles, and behavioural and electrophysiological effects identified those two patients as having a unique combination of lesion distribution and context effects. These results indicate a critical role for the left lateral-temporal and inferior parietal lobes, but not frontal cortex, in generating the alpha-beta power decreases underlying context-driven word production., (© 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

According to the competition account of lexical selection in word production, conceptually driven word retrieval involves the activation of a set of candidate words in left temporal cortex and competitive selection of the intended word from this set, regulated by frontal cortical mechanisms. However, the relative contribution of these brain regions to competitive lexical selection is uncertain. In the present study, five patients with left prefrontal cortex lesions (overlapping in ventral and dorsal lateral cortex), eight patients with left lateral temporal cortex lesions (overlapping in middle temporal gyrus), and 13 matched controls performed a picture-word interference task. Distractor words were semantically related or unrelated to the picture, or the name of the picture (congruent condition). Semantic interference (related vs. unrelated), tapping into competitive lexical selection, was examined. An overall semantic interference effect was observed for the control and left-temporal groups separately. The left-frontal patients did not show a reliable semantic interference effect as a group. The left-temporal patients had increased semantic interference in the error rates relative to controls. Error distribution analyses indicated that these patients had more hesitant responses for the related than for the unrelated condition. We propose that left middle temporal lesions affect the lexical activation component, making lexical selection more susceptible to errors.

The understanding of neuroplasticity following stroke is predominantly based on neuroimaging measures that cannot address the subsecond neurodynamics of impaired language processing. We combined behavioral and electrophysiological measures and structural-connectivity estimates to characterize neuroplasticity underlying successful compensation of language abilities after left-hemispheric stroke. We recorded the electroencephalogram from patients with stroke lesions to the left temporal lobe and from matched controls during context-driven word retrieval. Participants heard lead-in sentences that either constrained the final word ("He locked the door with the") or not ("She walked in here with the"). The last word was shown as a picture to be named. Individual-participant analyses were conducted, focusing on oscillatory power as a subsecond indicator of a brain region's functional neurophysiological computations. All participants named pictures faster following constrained than unconstrained sentences, except for two patients, who had extensive damage to the left temporal lobe. Left-lateralized alpha-beta oscillatory power decreased in controls pre-picture presentation for constrained relative to unconstrained contexts. In patients, the alpha-beta power decreases were observed with the same time course as in controls but were lateralized to the intact right hemisphere. The right lateralization depended on the probability of white-matter connections between the bilateral temporal lobes. The two patients who performed poorly behaviorally showed no alpha-beta power decreases. Our findings suggest that incorporating direct measures of neural activity into investigations of neuroplasticity can provide important neural markers to help predict language recovery, assess the progress of neurorehabilitation, and delineate targets for therapeutic neuromodulation. Hum Brain Mapp 38:3151-3162, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

The neural basis of reading and writing has been a source of inquiry as well as controversy in the neuroscience literature. Reading has been associated with both left posterior ventral temporal zones (termed the "visual word form area") as well as more dorsal zones, primarily in left parietal cortex. Writing has also been associated with left parietal cortex, as well as left sensorimotor cortex and prefrontal regions. Typically, the neural basis of reading and writing are examined in separate studies and/or rely on single case studies exhibiting specific deficits. Functional neuroimaging studies of reading and writing typically identify a large number of activated regions but do not necessarily identify the core, critical hubs. Last, due to constraints on the functional imaging environment, many previous studies have been limited to measuring the brain activity associated with single-word reading and writing, rather than sentence-level processing. In the current study, the brain correlates of reading and writing at both the single- and sentence-level were studied in a large sample of 111 individuals with a history of chronic stroke using voxel-based lesion symptom mapping (VLSM). VLSM provides a whole-brain, voxel-by-voxel statistical analysis of the role of distinct regions in a particular behavior by comparing performance of individuals with and without a lesion at every voxel. Rather than comparing individual cases or small groups with particular behavioral dissociations in reading and writing, VLSM allowed us to analyze data from a large, well-characterized sample of stroke patients exhibiting a wide range of reading and writing impairments. The VLSM analyses revealed that reading was associated with a critical left inferior temporo-occipital focus, while writing was primarily associated with the left supramarginal gyrus. Separate VLSM analyses of single-word versus sentence-level reading showed that sentence-level reading was uniquely associated with anterior to mid-portions of the middle and superior temporal gyri. Both single-word and sentence-level writing overlapped to a great extent in the left supramarginal gyrus, but sentence-level writing was associated with additional underlying white matter pathways such as the internal capsule. These findings suggest that critical aspects of reading and writing processes diverge, with reading relying critically on the ventral visual recognition stream and writing relying on a dorsal visuo-spatial-motor stream.

Our understanding of post‐stroke language function is largely based on older age groups, who show increasing age‐related brain pathology and neural reorganisation. To illustrate language outcomes in the young‐adult brain, we present the case of J., a 23‐year‐old woman with chronic aphasia from a left‐hemisphere stroke affecting the temporal lobe. Diffusion MRI‐based tractography indicated that J.'s language‐relevant white‐matter structures were severely damaged. Employing magnetoencephalography (MEG), we explored J.'s conceptual preparation and word planning abilities using context‐driven and bare picture‐naming tasks. These revealed naming deficits, manifesting as word‐finding difficulties and semantic paraphasias about half of the time. Naming was however facilitated by semantically constraining lead‐in sentences. Altogether, this pattern indicates disrupted lexical‐semantic and phonological retrieval abilities. MEG revealed that J.'s conceptual and naming‐related neural responses were supported by the right hemisphere, compared to the typical left‐lateralised brain response of a matched control. Differential recruitment of right‐hemisphere structures (330–440 ms post‐picture onset) was found concurrently during successful naming (right mid‐to‐posterior temporal lobe) and word‐finding attempts (right inferior frontal gyrus). Disconnection of the temporal lobes via corpus callosum was not critical for recruitment of the right hemisphere in visually guided naming, possibly due to neural activity right lateralising from the outset. Although J.'s right hemisphere responded in a timely manner during word planning, its lexical and phonological retrieval abilities remained modest. [ABSTRACT FROM AUTHOR]

Changes in brain organization following damage are commonly observed, but they remain poorly understood. These changes are often studied with imaging techniques that overlook the temporal granularity at which language processes occur. By contrast, electrophysiological measures provide excellent temporal resolution. To test the suitability of magnetoencephalography (MEG) to track language‐related neuroplasticity, the present study aimed at establishing the spectro‐temporo‐spatial across‐session consistency of context‐driven picture naming in healthy individuals, using MEG in two test–retest sessions. Spectro‐temporo‐spatial test–retest consistency in a healthy population is a prerequisite for studying neuronal changes in clinical populations over time. For this purpose, 15 healthy speakers were tested with MEG while performing a context‐driven picture‐naming task at two time points. Participants read a sentence missing the final word and named a picture completing the sentence. Sentences were constrained or unconstrained toward the picture, such that participants could either retrieve the picture name through sentence context (constrained sentences), or could only name it after the picture appeared (unconstrained sentences). The context effect (constrained versus unconstrained) in picture‐naming times had a strong effect size and high across‐session consistency. The context MEG results revealed alpha–beta power decreases (10–20 Hz) in the left temporal and inferior parietal lobule that were consistent across both sessions. As robust spectro‐temporo‐spatial findings in a healthy population are required for working toward longitudinal patient studies, we conclude that using context‐driven language production and MEG is a suitable way to examine language‐related neuroplasticity after brain damage. [ABSTRACT FROM AUTHOR]

The neural basis of reading and writing has been a source of inquiry as well as controversy in the neuroscience literature. Reading has been associated with both left posterior ventral temporal zones (termed the “visual word form area”) as well as more dorsal zones, primarily in left parietal cortex. Writing has also been associated with left parietal cortex, as well as left sensorimotor cortex and prefrontal regions. Typically, the neural basis of reading and writing are examined in separate studies and/or rely on single case studies exhibiting specific deficits. Functional neuroimaging studies of reading and writing typically identify a large number of activated regions but do not necessarily identify the core, critical hubs. Last, due to constraints on the functional imaging environment, many previous studies have been limited to measuring the brain activity associated with single-word reading and writing, rather than sentence-level processing. In the current study, the brain correlates of reading and writing at both the single- and sentence-level were studied in a large sample of 111 individuals with a history of chronic stroke using voxel-based lesion symptom mapping (VLSM). VLSM provides a whole-brain, voxel-by-voxel statistical analysis of the role of distinct regions in a particular behavior by comparing performance of individuals with and without a lesion at every voxel. Rather than comparing individual cases or small groups with particular behavioral dissociations in reading and writing, VLSM allowed us to analyze data from a large, well-characterized sample of stroke patients exhibiting a wide range of reading and writing impairments. The VLSM analyses revealed that reading was associated with a critical left inferior temporo-occipital focus, while writing was primarily associated with the left supramarginal gyrus. Separate VLSM analyses of single-word versus sentence-level reading showed that sentence-level reading was uniquely associated with anterior to mid-portions of the middle and superior temporal gyri. Both single-word and sentence-level writing overlapped to a great extent in the left supramarginal gyrus, but sentence-level writing was associated with additional underlying white matter pathways such as the internal capsule. These findings suggest that critical aspects of reading and writing processes diverge, with reading relying critically on the ventral visual recognition stream and writing relying on a dorsal visuo-spatial-motor stream. [ABSTRACT FROM AUTHOR]

Picture naming is a language task that involves multiple neural networks and is used to probe aphasia-induced language deficits. The pattern of neural activation seen in healthy individuals during picture naming is disrupted in individuals with aphasia, but the time-course of the disruption remains unclear. Specifically, it remains unclear which anatomical and temporal aspects of neural processing are necessary for correct naming. Here, we tested two individuals with stroke induced aphasia, and compared the differences in the event-related potentials (ERPs) and current sources when they made correct vs. erroneous responses during picture naming. The pre-articulatory ERP activity was significantly different between the two responses. Current source analysis revealed that the ability to recruit left temporal and frontal areas within a 300-550 ms time window after stimulus onset contributed to correct responses. These results suggest that targeted neuromodulation in these areas could lead to better treatment outcomes in patients with aphasia. [ABSTRACT FROM AUTHOR]