Speech and lexico-semantic errors during direct cortical stimulation mapping of the language-dominant hemisphere: effects of object and action naming.

OBJECTIVE: In this retrospective study, the authors aimed to establish the stereotactically defined probability distribution for speech (i.e., anarthria, speech arrest) and lexico-semantic errors (i.e., anomia) through direct cortical stimulation (DCS) by using two tasks: action naming and object naming. They also analyzed the patterns of interindividual variability in the localization of the language sites involved, and investigated whether any patient or lesion location factors were associated with greater variability. METHODS: Eighty-one Italian-speaking patients who underwent awake surgery between 2010 and 2021 for low- and high-grade gliomas in eloquent areas of the language-dominant hemisphere were entered in the analyses. The intraoperative DCS protocol included automatic speech tasks, object naming, and action naming. The position of the tags, as depicted on the intraoperative video or photograph, was transposed into Montreal Neurological Institute space. Subsequently, a 2D scatterplot and cluster analysis were performed. Associations between various clinical and radiological characteristics and the quantity of positive stimulated sites were determined by univariate analyses using binary logistic regression. Associated variables (p < 0.2) were included in stepwise multivariate logistic regression with backward elimination (p < 0.05). RESULTS: A total of 1380 cortical sites were stimulated, with a positive response in 511 cases (37%). Most anarthric errors were triggered when stimulating the left precentral gyrus, and most speech arrest errors were elicited when stimulating the left posterior inferior frontal gyrus. Anomias were found in the left inferior frontal gyrus and in the posterior part of the left temporal lobe for object naming. DCS to the left dorsal premotor cortex elicited anomic errors for action naming. Anomias were also elicited during DCS to the left posterior temporal lobe, with both object and action naming. CONCLUSIONS: The distribution of speech and lexico-semantic errors is in line with the current literature. The action-naming results are new and mostly involve the dorsal premotor cortex. These findings stress the importance of maximizing the use of different language tasks during surgery, because even when looking for the same type of errors, different tasks may be better suited to map specific brain regions. DCS with action and object naming identifies more positive sites than object naming alone.

Functional maps of direct electrical stimulation-induced speech arrest and anomia: a multicentre retrospective study.

Direct electrical stimulation, the transient 'lesional' method probing brain function, has been utilized in identifying the language cortex and preserving language function during epilepsy and neuro-oncological surgeries for about a century. However, comparison of functional maps of the language cortex across languages/continents based on cortical stimulation remains unclear. We conducted a retrospective multicentre study including four cohorts of direct electrical stimulation mapping from four centres across three continents, where three indigenous languages (English, French and Mandarin) are spoken. All subjects performed the two most common language tasks: number counting and picture naming during stimulation. All language sites were recorded and normalized to the same brain template. Next, Spearman's correlation analysis was performed to explore the consistency of the distributions of the language cortex across centres, a kernel density estimation to localize the peak coordinates, and a hierarchical cluster analysis was performed to detect the crucial epicenters. A total of 598 subjects with 917 speech arrest sites (complete interruption of ongoing counting) and 423 anomia sites (inability to name or misnaming) were included. Different centres presented highly consistent distribution patterns for speech arrest (Spearman's coefficient r ranged from 0.60 to 0.85, all pair-wise correlations P < 0.05), and similar patterns for anomia (Spearman's coefficient r ranged from 0.37 to 0.80). The combinational speech arrest map was divided into four clusters: cluster 1 mainly located in the ventral precentral gyrus and pars opercularis, which contained the peak of speech arrest in the ventral precentral gyrus; cluster 2 in the ventral and dorsal precentral gyrus; cluster 3 in the supplementary motor area; cluster 4 in the posterior superior temporal gyrus and supramarginal gyrus. The anomia map revealed two clusters: one was in the posterior part of the superior and middle temporal gyri, which peaked at the posterior superior temporal gyrus; and the other within the inferior frontal gyrus, peaked at the pars triangularis. This study constitutes the largest series to date of language maps generated from direct electrical stimulation mapping. The consistency of data provides evidence for common language networks across languages, in the context of both speech and naming circuit. Our results not only clinically offer an atlas for language mapping and protection, but also scientifically provide better insight into the functional organization of language networks.

Analysis of naming processing stages in patients with mild Alzheimer.

In the evaluation of the nature of naming disorders, there is a rapid increase of anomia with the progression of Alzheimer's disease (AD), which is associated with whole brain atrophy. Although numerous studies have investigated this naming disorder, there is limited information on naming procedures in these patients. Reaction time (RT) is highly sensitive to dementia and provides an accurate measurement. The present study investigated the RT of each underlying level of naming in patients with mild AD and identified the nature of anomia in these patients. The study consisted of 24 healthy elderly and 22 mild AD patients who participated in experiments that were designed for evaluating each level of Levelt's model. Responses were divided into three groups of correct, false, and no-response and their RTs were calculated. The statistical analyses showed significant differences between healthy elderly and patients with mild AD in terms of access to the concept and the phonological form of the words. Moreover, significant differences in the type of responses were observed between correct and false responses of both groups. There was a significant difference between the no-response cases except in the case of lemma access for singular and plural names in other tasks. The results suggest that patients with mild AD have problems at the conceptual stage and access to the phonological form of a word.

C9orf72 Repeat Expansion Does Not Affect the Phenotype in Primary Progressive Aphasia.

Primary progressive aphasia (PPA) forms the spectrum of language variants of frontotemporal lobar degeneration (FTLD), including three subtypes each consisting of distinctive speech and language features. Repeat expansion in C9orf72 gene is the most common genetic cause of FTLD. However, thus far only little is known about the effects of the C9orf72 repeat expansion on the phenotype of PPA. This retrospective study aimed at determining the differences between the PPA phenotypes of the C9orf72 expansion carriers and non-carriers. Our results demonstrated no significant differences between these groups, indicating that the C9orf72 repeat expansion does not substantially affect the phenotype of PPA.

Temporal lobe regions essential for preserved picture naming after left temporal epilepsy surgery.

OBJECTIVE: To define left temporal lobe regions where surgical resection produces a persistent postoperative decline in naming visual objects. METHODS: Pre- and postoperative brain magnetic resonance imaging data and picture naming (Boston Naming Test) scores were obtained prospectively from 59 people with drug-resistant left temporal lobe epilepsy. All patients had left hemisphere language dominance at baseline and underwent surgical resection or ablation in the left temporal lobe. Postoperative naming assessment occurred approximately 7 months after surgery. Surgical lesions were mapped to a standard template, and the relationship between presence or absence of a lesion and the degree of naming decline was tested at each template voxel while controlling for effects of overall lesion size. RESULTS: Patients declined by an average of 15% in their naming score, with wide variation across individuals. Decline was significantly related to damage in a cluster of voxels in the ventral temporal lobe, located mainly in the fusiform gyrus approximately 4-6 cm posterior to the temporal tip. Extent of damage to this region explained roughly 50% of the variance in outcome. Picture naming decline was not related to hippocampal or temporal pole damage. SIGNIFICANCE: The results provide the first statistical map relating lesion location in left temporal lobe epilepsy surgery to picture naming decline, and they support previous observations of transient naming deficits from electrical stimulation in the basal temporal cortex. The critical lesion is relatively posterior and could be avoided in many patients undergoing left temporal lobe surgery for intractable epilepsy.

Morphometric correlates of anomia in patients with small left temporopolar lesions.

Visual object naming is a complex cognitive process that engages an interconnected network of cortical regions moving from occipitotemporal to anterior-inferior temporal cortices, and extending into the inferior frontal cortex. Naming can fail for diverse reasons, and different stages of the naming multi-step process appear to be reliant upon the integrity of different neuroanatomical locations. While the neural correlates of semantic errors have been extensively studied, the neural basis of omission errors remains relatively unspecified. Although a strong line of evidence supports an association between anterior temporal lobe damage and semantic errors, there are some studies suggesting that the anterior temporal lobe could be also associated with omissions. However, support for this hypothesis comes from studies with patients in whom damage affected extensive brain regions, sometimes bilaterally. Here, we availed of a group of 12 patients with epilepsy associated with a small lesion at the tip of the left temporal pole. Using an unbiased surface-based morphometry methodology, we correlated two morphological features with errors observed during visual naming. Analyses revealed a correlation between omission errors and reduced local gyrification index in three cortical clusters: one in the left anteromedial temporal lobe region (AMTL) and two in the left anterior cingulate cortex (ACC). Our findings support the view that regions in ACC and AMTL are critical structures within a network engaged in word selection from semantics.

The role of executive control in post-stroke aphasia treatment.

Executive control (EC) ability is increasingly emerging as an important predictor of post-stroke aphasia recovery. This study examined whether EC predicted immediate treatment gains, treatment maintenance and generalization after naming therapy in ten adults with mild to severe chronic post-stroke aphasia. Performance on multiple EC tasks allowed for the creation of composite scores for common EC, and the EC processes of shifting, inhibition and working memory (WM) updating. Participants were treated three times a week for five weeks with a phonological naming therapy; difference scores in naming accuracy of treated and untreated words (assessed pre, post, four- and eight-weeks after therapy) served as the primary outcome measures. Results from simple and multiple linear regressions indicate that individuals with better shifting and WM updating abilities demonstrated better maintenance of treated words at four-week follow-up, and those with better common EC demonstrated better maintenance of treated words at both four- and eight-week follow-ups. Better shifting ability also predicted better generalization to untreated words post-therapy. Measures of EC were not indicative of improvements on treated words immediately post-treatment, nor of generalization to untreated words at follow-up. Findings suggest that immediate treatment gains, maintenance and generalization may be supported by different underlying mechanisms.

Temporal and Episodic Analyses of the Story of Cinderella in Latent Aphasia.

Purpose The purpose of this study was to improve our understanding of the language characteristics of people with latent aphasia using measures that examined temporal (i.e., real-time) and episodic organization of discourse production. Method Thirty AphasiaBank participants were included (10 people with latent aphasia, 10 people with anomic aphasia, and 10 neurotypical control participants). Speech material of Cinderella narratives was analyzed with Praat software. We devised a protocol that coded the presence and duration of all speech segments, dysfluencies such as silent and filled pauses, and other speech behaviors. Using these durations, we generated a range of temporal measures such as speech, articulation, and pure word rates. Narratives were also coded into episodes, which provided information about the discourse macrostructure abilities of the participants. Results The latent aphasia group differed from controls in number of words produced, silent pause duration, and speech rate, but not articulation rate or pure word rate. Episodic organization of the narratives was similar in these 2 groups. The latent and anomic aphasia groups were similar in most measures, apart from articulation rate, which was lower in the anomic group. The anomic aphasia group also omitted more episodes than the latent aphasia group. Conclusions The differences between latent aphasia and neurotypical controls can be attributed to a processing speed deficit. We propose that this deficit results in an impaired ability to process information from multiple cognitive domains simultaneously.

Typicality-based semantic treatment for anomia results in multiple levels of generalisation.

This study investigated the effects of typicality-based semantic feature analysis (SFA) treatment on generalisation across three levels: untrained related items, semantic/phonological processing tasks, and measures of global language function. Using a single-subject design with group-level analyses, 27 persons with aphasia (PWA) received typicality-based SFA to improve their naming of atypical and/or typical exemplars. Progress on trained, untrained, and monitored items was measured weekly. Pre- and post-treatment assessments were administered to evaluate semantic/phonological processing and overall language ability. Ten PWA served as controls. For the treatment participants, the likelihood of naming trained items accurately was significantly higher than for monitored items over time. When features of atypical items were trained, the likelihood of naming untrained typical items accurately was significantly higher than for untrained atypical items over time. Significant gains were observed on semantic/phonological processing tasks and standardised assessments after therapy. Different patterns of near and far transfer were seen across treatment response groups. Performance was also compared between responders and controls. Responders demonstrated significantly more improvement on a semantic processing task than controls, but no other significant change score differences were found between groups. In addition to positive treatment effects, typicality-based SFA naming therapy resulted in generalisation across multiple levels.

What Cognitive Neurology Teaches Us about Our Experience of Color.

Color provides valuable information about the environment, yet the exact mechanisms explaining how colors appear to us remain poorly understood. Retinal signals are processed in the visual cortex through high-level mechanisms that link color perception with top-down expectations and knowledge. Here, we review the neuroimaging evidence about color processing in the brain, and how it is affected by acquired brain lesions in humans. Evidence from patients with brain-damage suggests that high-level color processing may be divided into at least three modules: perceptual color experience, color naming, and color knowledge. These modules appear to be functionally independent but richly interconnected, and serve as cortical relays linking sensory and semantic information, with the final goal of directing object-related behavior. We argue that the relations between colors and their objects are key mechanisms to understand high-level color processing.

Variation in language mixing in multilingual aphasia.

Mixing languages within a sentence or a conversation is a common practice among many speakers of multiple languages. Language mixing found in multilingual speakers with aphasia has been suggested to reflect deficits associated with the brain lesion. In this paper, we examine language mixing behaviour in multilingual people with aphasia to test the hypothesis that the use of language mixing reflects a communicative strategy. We analysed connected language production elicited from 11 individuals with aphasia. Words produced were coded as mixed or not. Frequencies of mixing were tabulated for each individual in each of her or his languages in each of two elicitation tasks (Picture sequence description, Narrative production). We tested the predictions that there would be more word mixing: for participants with greater aphasia severity; while speaking in a language of lower post-stroke proficiency; during a task that requires more restricted word retrieval; for people with non-fluent aphasia, while attempting to produce function words (compared to content words); and that there would be little use of a language not known to the interlocutors. The results supported three of the five predictions. We interpret our data to suggest that multilingual speakers with aphasia mix words in connected language production primarily to bypass instances of word-retrieval difficulties, and typically avoid pragmatically inappropriate language mixing.

Self-reported inner speech relates to phonological retrieval ability in people with aphasia.

Many individuals with aphasia report the ability to say words in their heads despite spoken naming difficulty. Here, we examined individual differences in the experience of inner speech (IS) in participants with aphasia to test the hypotheses that self-reported IS reflects intact phonological retrieval and that articulatory output processing is not essential to IS. Participants (N = 53) reported their ability to name items correctly internally during a silent picture-naming task. We compared this measure of self-reported IS to spoken picture naming and a battery of tasks measuring the underlying processes required for naming (i.e., phonological retrieval and output processing). Results from three separate analyses of these measures indicate that self-reported IS relates to phonological retrieval and that speech output processes are not a necessary component of IS. We suggest that self-reported IS may be a clinically valuable measure that could assist in clinical decision-making regarding anomia diagnosis and treatment.

The Neural and Behavioral Correlates of Anomia Recovery following Personalized Observation, Execution, and Mental Imagery Therapy: A Proof of Concept.

The impact of sensorimotor strategies on aphasia recovery has rarely been explored. This paper reports on the efficacy of personalized observation, execution, and mental imagery (POEM) therapy, a new approach designed to integrate sensorimotor and language-based strategies to treat verb anomia, a frequent aphasia sign. Two participants with verb anomia were followed up in a pre-/posttherapy fMRI study. POEM was administered in a massed stimulation schedule, with personalized stimuli, resulting in significant improvement in both participants, with both trained and untrained items. Given that the latter finding is rarely reported in the literature, the evidence suggests that POEM favors the implementation of a word retrieval strategy that can be integrated and generalized. Changes in fMRI patterns following POEM reflect a reduction in the number of recruited areas supporting naming and the recruitment of brain areas that belong to the language and mirror neuron systems. The data provide evidence on the efficacy of POEM for verb anomia, while pointing to the added value of combined language and sensorimotor strategies for recovery from verb anomia, contributing to the consolidation of a word retrieval strategy that can be better generalized to untrained words. Future studies with a larger sample of participants are required to further explore this avenue.

A lexical semantic hub for heteromodal naming in middle fusiform gyrus.

Semantic memory underpins our understanding of objects, people, places, and ideas. Anomia, a disruption of semantic memory access, is the most common residual language disturbance and is seen in dementia and following injury to temporal cortex. While such anomia has been well characterized by lesion symptom mapping studies, its pathophysiology is not well understood. We hypothesize that inputs to the semantic memory system engage a specific heteromodal network hub that integrates lexical retrieval with the appropriate semantic content. Such a network hub has been proposed by others, but has thus far eluded precise spatiotemporal delineation. This limitation in our understanding of semantic memory has impeded progress in the treatment of anomia. We evaluated the cortical structure and dynamics of the lexical semantic network in driving speech production in a large cohort of patients with epilepsy using electrocorticography (n = 64), functional MRI (n = 36), and direct cortical stimulation (n = 30) during two generative language processes that rely on semantic knowledge: visual picture naming and auditory naming to definition. Each task also featured a non-semantic control condition: scrambled pictures and reversed speech, respectively. These large-scale data of the left, language-dominant hemisphere uniquely enable convergent, high-resolution analyses of neural mechanisms characterized by rapid, transient dynamics with strong interactions between distributed cortical substrates. We observed three stages of activity during both visual picture naming and auditory naming to definition that were serially organized: sensory processing, lexical semantic processing, and articulation. Critically, the second stage was absent in both the visual and auditory control conditions. Group activity maps from both electrocorticography and functional MRI identified heteromodal responses in middle fusiform gyrus, intraparietal sulcus, and inferior frontal gyrus; furthermore, the spectrotemporal profiles of these three regions revealed coincident activity preceding articulation. Only in the middle fusiform gyrus did direct cortical stimulation disrupt both naming tasks while still preserving the ability to repeat sentences. These convergent data strongly support a model in which a distinct neuroanatomical substrate in middle fusiform gyrus provides access to object semantic information. This under-appreciated locus of semantic processing is at risk in resections for temporal lobe epilepsy as well as in trauma and strokes that affect the inferior temporal cortex-it may explain the range of anomic states seen in these conditions. Further characterization of brain network behaviour engaging this region in both healthy and diseased states will expand our understanding of semantic memory and further development of therapies directed at anomia.

A cognitive psychometric model for assessment of picture naming abilities in aphasia.

Picture naming impairments are a typical feature of stroke-induced aphasia. Overall accuracy and rates of different error types are used to make inferences about the severity and nature of damage to the brain's language network. Currently available assessment tools for picture naming accuracy treat it as a unidimensional measure, while assessment tools for error types treat items homogenously, contrary to findings from psycholinguistic investigations of word production. We created and tested a new cognitive psychometric model for assessment of picture naming responses, using cognitive theory to specify latent processing decisions during the production of a naming attempt, and using item response theory to separate the effects of item difficulty and participant ability on these internal processing decisions. The model enables multidimensional assessment of latent picture naming abilities on a common scale, with a relatively large cohort for normative reference. We present the results of 4 experiments testing our interpretation of the model's parameters, as they apply to picture naming predictions, lexical properties of the items, statistical properties of the lexicon, and participants' scores on other tests. We also created a website for researchers and clinicians to analyze item-level data using our model, providing estimates of latent abilities and percentile scores, as well as credible intervals to help gauge the reliability of the estimated model parameters and identify meaningful changes. To the extent that the model is successful, the estimated parameter values may aid in treatment decisions and progress monitoring, or they may help elucidate the functional properties of brain networks. (PsycINFO Database Record

Phonotactic processing deficit following left-hemisphere stroke.

The neural basis of speech processing is still a matter of great debate. Phonotactic knowledge-knowledge of the allowable sound combinations in a language-remains particularly understudied. The purpose of this study was to investigate the brain regions crucial to phonotactic knowledge in left-hemisphere stroke survivors. Results were compared to areas in which gray matter anatomy related to phonotactic knowledge in healthy controls. 44 patients with chronic left-hemisphere stroke, and 32 controls performed an English-likeness rating task on 60 auditory non-words of varying phonotactic regularities. They were asked to rate on a 1-5 scale, how close each non-word sounded to English. Patients' performance was compared to that of healthy controls, using mixed effects modeling. Multivariate lesion-symptom mapping and voxel-based morphometry were used to find the brain regions important for phonotactic processing in patients and controls respectively. The results showed that compared to controls, stroke survivors were less sensitive to phonotactic regularity differences. Lesion-symptom mapping demonstrated that a loss of sensitivity to phonotactic regularities was associated with lesions in left angular gyrus and posterior middle temporal gyrus. Voxel-based morphometry also revealed a positive correlation between gray matter density in left angular gyrus and sensitivity to phonotactic regularities in controls. We suggest that the angular gyrus is used to compare the incoming speech stream to internal predictions based on the frequency of sound sequences in the language derived from stored lexical representations in the posterior middle temporal gyrus.

Whole network, temporal and parietal lobe contributions to the earliest phases of language production.

We investigated whether it is possible to study the network dynamics and the anatomical regions involved in the earliest moments of picture naming by using invasive electroencephalogram (EEG) traces to predict naming errors. Four right-handed participants with focal epilepsy explored with extensive stereotactic implant montages that recorded temporal, parietal and occipital regions -in two patients of both hemispheres-named a total of 228 black and white pictures in three different sessions recorded in different days. The subjects made errors that involved anomia and semantic dysphasia, which related to word frequency and not to visual complexity. Using different modalities of spectrum analysis and classification with a support vector machine (SVM) we could predict errors with rates that ranged from slightly above chance level to 100%, even in the preconscious phase, i.e., 100 msec after stimulus presentation. The highest rates were obtained using the gamma bands of all contact spectra without averaging, which implies a fine modulation of the neuronal activity at a network level. Despite no subset of nodes could match the whole set, rates close to the best prediction scores were obtained through the spectra of the temporal-parietal and temporal-occipital junction along with the temporal pole and hippocampus. When both hemispheres were explored nodes from the left side dominated in the best subsets. We argue that posterior temporal regions, especially of the dominant side, are involved very early, even in the preconscious phase (100 msec), in language production.

Influence of Linguistic and Nonlinguistic Variables on Generalization and Maintenance Following Phonomotor Treatment for Aphasia.

PURPOSE: Although phonomotor treatment shows promise as an effective intervention for anomia in people with aphasia, responses to this treatment are not consistent across individuals. To better understand this variability, we examined the influence of 5 participant characteristics-age, time postonset, aphasia severity, naming impairment, and error profile-on generalization and maintenance of confrontation naming and discourse abilities following phonomotor treatment. METHOD: Using retrospective data from 26 participants with aphasia who completed a 6-week phonomotor treatment program, we examined the relationships between participant characteristics of interest and change scores on confrontation naming and discourse tasks, measured pretreatment, immediately following treatment, and 3 months following treatment. RESULTS: Although the participant characteristics of aphasia severity and error profile appeared to predict generalization to improved confrontation naming of untrained items and discourse performance, a post hoc analysis revealed that no one characteristic predicted generalization across participants at 3 months posttreatment. CONCLUSIONS: Response to phonomotor treatment does not appear to be influenced by aphasia and anomia severity level, error profile, participant age, or time postonset. Other factors, however, may influence response to intensive aphasia treatment and are worthy of continued exploration.

The timing of spontaneous detection and repair of naming errors in aphasia.

This study examined the timing of spontaneous self-monitoring in the naming responses of people with aphasia. Twelve people with aphasia completed a 615-item naming test twice, in separate sessions. Naming attempts were scored for accuracy and error type, and verbalizations indicating detection were coded as negation (e.g., "no, not that") or repair attempts (i.e., a changed naming attempt). Focusing on phonological and semantic errors, we measured the timing of the errors and of the utterances that provided evidence of detection. The effects of error type and detection response type on error-to-detection latencies were analyzed using mixed-effects regression modeling. We first asked whether phonological errors and semantic errors differed in the timing of the detection process or repair planning. Results suggested that the two error types primarily differed with respect to repair planning. Specifically, repair attempts for phonological errors were initiated more quickly than repair attempts for semantic errors. We next asked whether this difference between the error types could be attributed to the tendency for phonological errors to have a high degree of phonological similarity with the subsequent repair attempts, thereby speeding the programming of the repairs. Results showed that greater phonological similarity between the error and the repair was associated with faster repair times for both error types, providing evidence of error-to-repair priming in spontaneous self-monitoring. When controlling for phonological overlap, significant effects of error type and repair accuracy on repair times were also found. These effects indicated that correct repairs of phonological errors were initiated particularly quickly, whereas repairs of semantic errors were initiated relatively slowly, regardless of their accuracy. We discuss the implications of these findings for theoretical accounts of self-monitoring and the role of speech error repair in learning.

Discourse Characteristics in Aphasia Beyond the Western Aphasia Battery Cutoff.

PURPOSE: This study examined discourse characteristics of individuals with aphasia who scored at or above the 93.8 cutoff on the Aphasia Quotient subtests of the Western Aphasia Battery-Revised (WAB-R; Kertesz, 2007). They were compared with participants without aphasia and those with anomic aphasia. METHOD: Participants were from the AphasiaBank database and included 28 participants who were not aphasic by WAB-R score (NABW), 92 participants with anomic aphasia, and 177 controls. Cinderella narratives were analyzed using the Computerized Language Analysis programs (MacWhinney, 2000). Outcome measures were words per minute, percent word errors, lexical diversity using the moving average type-token ratio (Covington, 2007b), main concept production, number of utterances, mean length of utterance, and proposition density. RESULTS: Results showed that the NABW group was significantly different from the controls on all measures except MLU and proposition density. These individuals were compared to participants without aphasia and those with anomic aphasia. CONCLUSION: Individuals with aphasia who score above the WAB-R Aphasia Quotient cutoff demonstrate discourse impairments that warrant both treatment and special attention in the research literature.