Background Word class naming deficits are commonly seen in aphasia resulting from stroke (StrAph) and primary progressive aphasia (PPA), with differential production of nouns (objects) and verbs (actions) found based on StrAph type or PPA variant for some individuals. Studies to date, however, have not compared word class naming (or comprehension) ability in the two aphasic disorders. In addition, there are no available measures for testing word class deficits, which control for important psycholinguistic variables across language domains. This study examined noun and verb production and comprehension in individuals with StrAph and PPA using a new test, the Northwestern Naming Battery (NNB; Thompson & Weintraub, experimental version), developed explicitly for this purpose. In addition, we tested verb type effects, based on verb argument structure characteristics, which also is addressed by the NNB. Method Fifty-two participants with StrAph (33 agrammatic, Broca’s (StrAg); 19 anomic (StrAn)) and 28 PPA (10 agrammatic (PPA-G); 14 logopenic (PPA-L); 4 semantic (PPA-S)) were included in the study. Nouns and verbs were tested in the Confrontation Naming and Auditory Comprehension subtests of the NNB, with scores used to compute noun to verb ratios as well as performance by verb type. Performance patterns within and across StrAph and PPA groups were then examined. The external validity of the NNB also was tested by comparing (a) NNB Noun Naming scores to the Boston Naming Test (BNT; Kaplan, Goodglass, & Weintraub, 1983) and Western Aphasia Battery (WAB-R, Kertesz, 2007) Noun Naming subtest scores, (b) NNB Verb Naming scores to the Boston Diagnostic Aphasia Examination (BDAE; Goodglass, Kaplan & Barresi, 2001) Action Naming score (for StrAph participants only), and (c) NNB Comprehension subtest scores to WAB-R Auditory Comprehension subtest scores. Outcomes and Results Both agrammatic (StrAg and PPA-G) groups showed significantly greater difficulty producing verbs compared to nouns, but no comprehension impairment for either word class. Whereas, three of the four PPA-S participants showed poorer noun compared to verb production, as well as comprehension. However, neither the StrAn or PPA-L participants showed significant differences between the two word classes in production or comprehension. In addition, similar to the agrammatic participants, the StrAn participants showed a significant transitivity effect, producing intransitive (one-argument) verbs with greater accuracy than transitive (two- and three-argument) verbs. However, no transitivity effects were found for the PPA-L or PPA-S participants. There were significant correlations between NNB scores and all external validation measures. Conclusions These data indicate that the NNB is sensitive to word class deficits in stroke and neurodegenerative aphasia. This is important both clinically for treatment planning and theoretically to inform both psycholinguistic and neural models of language processing.

Previous studies indicate that repetition is affected in primary progressive aphasia (PPA), particularly in the logopenic variant, due to limited auditory-verbal short-term memory (avSTM). We tested repetition of phrases varied by length (short, long) and meaning (meaningful, non-meaningful) in 58 participants (22 logopenic, 19 nonfluent, and 17 semantic variants) and 21 healthy controls using a modified Bayles repetition test. We evaluated the relation between cortical thickness and repetition performance and whether sub-scores could discriminate PPA variants. Logopenic participants showed impaired repetition across all phrases, specifically in repeating long phrases and any phrases that were non-meaningful. Nonfluent, semantic, and healthy control participants only had difficulty repeating long, non-meaningful phrases. Poor repetition of long phrases was associated with cortical thinning in left temporo-parietal areas across all variants, highlighting the importance of these areas in avSTM. Finally, Bayles repetition phrases can assist classification in PPA, discriminating logopenic from nonfluent/semantic participants with 89% accuracy.

Complex sentence processing is supported by a left-lateralized neural network including inferior frontal cortex and posterior superior temporal cortex. This study investigates the pattern of connectivity and information flow within this network. We used fMRI BOLD data derived from 12 healthy participants reported in an earlier study (Thompson, C. K., Den Ouden, D. B., Bonakdarpour, B., Garibaldi, K., & Parrish, T. B. (2010b). Neural plasticity and treatment-induced recovery of sentence processing in agrammatism. Neuropsychologia, 48(11), 3211-3227) to identify activation peaks associated with object-cleft over syntactically less complex subject-cleft processing. Directed Partial Correlation Analysis was conducted on time series extracted from participant-specific activation peaks and showed evidence of functional connectivity between four regions, linearly between premotor cortex, inferior frontal gyrus, posterior superior temporal sulcus and anterior middle temporal gyrus. This pattern served as the basis for Dynamic Causal Modeling of networks with a driving input to posterior superior temporal cortex, which likely supports thematic role assignment, and networks with a driving input to inferior frontal cortex, a core region associated with syntactic computation. The optimal model was determined through both frequentist and Bayesian model selection and turned out to reflect a network with a primary drive from inferior frontal cortex and modulation of the connection between inferior frontal and posterior superior temporal cortex by complex sentence processing. The winning model also showed a substantive role for a feedback mechanism from posterior superior temporal cortex back to inferior frontal cortex. We suggest that complex syntactic processing is driven by word-order analysis, supported by inferior frontal cortex, in an interactive relation with posterior superior temporal cortex, which supports verb argument structure processing.

Introduction-Neuroimaging and lesion studies indicate a left hemisphere network for verb and verb argument structure processing, involving both frontal and temporoparietal brain regions. Although their verb comprehension is generally unimpaired, it is well known that individuals with agrammatic aphasia often present with verb production deficits, characterized by an argument structure complexity hierarchy, indicating faulty access to argument structure representations for production and integration into syntactic contexts. Recovery of verb processing in agrammatism, however, has received little attention and no studies have examined the neural mechanisms associated with improved verb and argument structure processing. In the present study we trained agrammatic individuals on verbs with complex argument structure in sentence contexts and examined generalization to verbs with less complex argument structure. The neural substrates of improved verb production were examined using functional magnetic resonance imaging (fMRI).Methods-Eight individuals with chronic agrammatic aphasia participated in the study (four experimental and four control participants). Production of three-argument verbs in active sentences was trained using a sentence generation task emphasizing the verb's argument structure and the thematic roles of sentential noun phrases. Before and after training, production of trained and untrained verbs was tested in naming and sentence production and fMRI scans were obtained, using an action naming task.Results-Significant pre-to post-training improvement in trained and untrained (one-and twoargument) verbs was found for treated, but not control, participants, with between-group differences found for verb naming, production of verbs in sentences, and production of argument structure. fMRI activation derived from post-treatment compared to pre-treatment scans revealed upregulation in cortical regions implicated for verb and argument structure processing in healthy controls. Conclusions-Training verb deficits emphasizing argument structure and thematic role mapping is effective for improving verb and sentence production and results in recruitment of neural networks engaged for verb and argument structure processing in healthy individuals.

Models of reading must explain how orthographic input activates a phonological representation, and elicits the retrieval of word meaning from semantic memory. Comparisons between tasks that theoretically differ with respect to the degree to which they rely on connections between orthographic, phonological and semantic systems during reading can thus provide valuable insight into models of reading, but such direct comparisons are not well-represented in the literature. An ALE meta-analysis explored lexicality effects directly contrasting words and pseudowords using the lexical decision task and overt or covert naming, which we assume rely most on the semantic and phonological systems, respectively. Interactions between task and lexicality effects demonstrate that different demands of the lexical decision and naming tasks lead to different manifestations of lexicality effects.