Cortical and structural connectivity damage correlated with impaired syntactic processing

Problems with sentence processing and production are not exclusive to speakers with agrammatic aphasia. Besides peripheral problems with auditory processing or articulatory control, lexical retrieval, attention and short-term memory deficits may all underlie difficulties with organizing words into sentences, applying inflectional morphology and correctly accessing and processing verb argument structure. Lesions that result in sentence processing problems are therefore not homogeneously limited to a small region. However, sentence processing and production can be broken up into components, in order to investigate the brain-behavior relationship in greater detail. The Northwestern Assessment of Verbs and Sentences (NAVS) allows for such investigations, as it consists of several tasks that tap into different components of syntactic processing (Cho-Reyes & Thompson, 2012). In particular, the NAVS focuses on the pivotal role of verbs and verb argument structure in sentence (de)construction. With respect to structural syntactic features that affect sentence processing, it is of interest to investigate deficits that are characterized by greater problems with noncanonical sentence structures, compared to canonical structures. Patients with such a pattern of impairment may be considered to have a specific deficit in complex syntactic processing. Brain-behavior investigations that focus on such patterns may yield greater insight into regions and/or networks that serve a particular role in the syntactic computations that underlie the relation between canonical and noncanonical sentences (Magnusdottir et al., 2013). As part of a larger study into correlations between brain damage and functional deficits, we submitted participants to an MRI scanning protocol that included anatomical scans, diffusion tensor imaging, resting state functional imaging, and perfusion imaging. Such a combination of methods reduces the chance of underestimating the extent of stroke-induced brain damage and its effect on patient symptoms. We investigated correlations with performance on NAVS subtests, as well as with the ratio of performance on canonical versus noncanonical sentence structures

Design Fluency Subsequent to Onset of Aphasia or Right Hemisphere Brain Damage

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Patterns of Decline on Language Testing in Primary Progressive Aphasia

The aim of this study was to investigate patterns of decline on language testing in subtypes of primary progressive aphasia (PPA) and to examine the effects of other variables on rate of decline. Forty-six patients with PPA (mean age = 66.9 + 6.6; 27 female; mean education = 16.4 + 2.8) completed language testing. PPA subtypes were not distinguishable by rapidity of decline; however, there were different patterns of performance on language testing. Age and education did not affect rate of decline on any test. These results have implications for patient/family education regarding language deterioration and future planning

Voxel-lesion symptom mapping of coarse coding and suppression deficits in right hemisphere damaged patients

Several accounts of narrative comprehension deficits in adults with right hemisphere damage (RHD) focus on the basic comprehension processes of coarse semantic coding (CC) and suppression (SUP)1,2. CC activates wide-ranging aspects of word meaning, independent of the surrounding context. In RHD, CC deficits impair processing of more remote meanings/features of lexical-semantic representations (e.g., “rotten” as a feature of “apple”)3. The normal SUP process reduces mental activation of concepts that become contextually incompatible. SUP impairment in RHD is indexed by prolonged processing interference from contextually-inappropriate interpretations (e.g., the “ink” meaning of “pen,” in “He built a pen”)4,5. Adults with RHD may have deficits in CC, SUP, both, or neither6. Voxel-based lesion symptom mapping was used to identify right hemisphere (RH) anatomical correlates of CC and SUP deficits. Lesion-deficit correspondence data should help predict which RHD patients have which deficits and may be candidates for a deficit-focused treatment approach that simultaneously improves narrative comprehension7-9. The Bilateral Activation, Integration, and Selection (BAIS) framework of language processing10 suggests some basic hypotheses1. CC, related to the activation component, is hypothesized to involve posterior MTG and STG10,11. SUP, related to the attentionally-driven selection component, modulates lexical-level activation and message-level semantic integration to narrow representations to those most relevant to a comprehender’s goal. Selection is strongly associated with left IFGe.g,12 but RH IFG also is crucial for semantic filtering and selection13,14, especially for information more strongly active in the RH15. Basal ganglia circuits are likely involved, as well13,16

Korean Passive Sentence Comprehension Deficits and its Relation to Working Memory Capacity in Persons with Aphasia

The current study investigated Korean passive sentence comprehension deficits in aphasia and its underlying processing mechanisms using three types of syntactic structures: 1) active sentences with a 2-argument structure, 2) active sentences with a 3-argument structure, and 3) passive counterparts of active sentences with a 2-argument structure. Persons with aphasia showed differentially greater difficulties in passive than 2-place active sentences compared to the normal elderly adults, but the group differences were not significant between the passive and 3-place active sentences. Working memory, not the short-term memory, was significantly correlated with overall aphasia severity and performance on sentence comprehension tasks

Story Grammar Analysis in Persons with Mild Aphasia

Narratives are often the basis of daily conversational interactions. When narrative skills are compromised, functional conversation is negatively impacted. Narrative coherence can be impacted even in clinical populations with mild word-finding deficits, such as anomic aphasia (Andreetta, Cantagallo, & Marini, 2012). The narrative abilities of those individuals who have had a stroke (and perhaps a previous aphasia diagnosis) but who perform within the normal range on standardized aphasia assessment measures have not been characterized. As every clinician/clinical researcher knows, this subgroup still includes individuals who have difficulty in conversation, who cannot return to work, and whose life participation is negatively impacted. Using AphasiaBank categorization (as this study relies on AphasiaBank transcripts), we refer to this subgroup as “not aphasic by WAB” (NABW). In both persons with anomic aphasia (PWaAs) and NABWs, deficits may be so minor that they are not apparent on traditional standardized assessment measures, but it should not be assumed that they do not exist and do not affect functional communication abilities. Unfortunately, there is often very little help to be offered for this population. In order to continue progressive development of interventions for PWaAs and NABWs, more information regarding narrative strengths and weaknesses in this population is needed. Story grammar analysis is a well-known method of analyzing narrative discourse in several clinical populations and is likely to be sensitive to differences between closely matched groups. The specific aims of this study are to 1) determine if there are differences between PWaAs, NABW, and non-brain injured controls (NBIs) on production of story grammar components during retelling of the Cinderella story, and 2) to examine the relationship between story grammar measures and an easily and quickly derived discourse measure called CoreLex to further characterize the relationship between micro- and macro-level processes in persons with mild aphasia

Feedback and feedforward control in apraxia of speech: Noise masking effects on fricative production

The present study tested two hypotheses about apraxia of speech (AOS), framed in the DIVA model (Guenther, Ghosh, & Tourville, 2006). The DIVA model assumes that speech targets are regions in auditory space, and combines two mechanisms to reach those targets: feedback control and feedforward control. The Feedforward System Deficit (FF) hypothesis states that feedforward control is impaired in AOS, with consequently a greater reliance on feedback control (Jacks, 2008; Maas, Mailend, & Guenther, 2013). The Feedback System Deficit (FB) hypothesis states that feedback control is impaired in AOS; for example, self-generated auditory feedback may be disruptive (cf. Ballard & Robin, 2007). We tested these hypotheses by measuring acoustic fricative contrast in normal listening and noise masking conditions. The rationale is that noise masking effectively eliminates the self-generated auditory feedback signal, thus forcing a greater reliance on feedforward control. For unimpaired speakers, we predict a reduction in acoustic contrast, given evidence that speakers monitor and use auditory feedback on-line (e.g., Tourville, Reilly, & Guenther, 2008), though this reduction is expected to be small given the robust feedforward commands presumably available to unimpaired speakers (e.g., Perkell, 2012). For speakers with AOS, the FF hypothesis predicts greater reduction of contrast with masking in AOS patients than in controls, because removal of auditory feedback will reveal the impaired feedforward commands. The FB hypothesis predicts increased contrast with feedback masking, because removal of interfering auditory feedback enables intact feedforward commands to produce adequate contrasts

Evaluation of Demographic and Language Predictors of Main Concept Production in Spanish/English Bilingual Discourse Using Nicolas and Brookshire Stimuli

Hispanics are the fastest growing minority group in the US, and stroke incidence for Hispanics is higher than that of non-Hispanic caucasians (Dong et al., 2012). Since stroke is the leading cause of aphasia, and the majority of Hispanics are bilingual Spanish/English speakers, there is a growing need for appropriate assessment methods for bilingual aphasia. One challenge in assessing bilinguals is their diverse language backgrounds, including differences in proficiency and use across languages. Previous studies have reported correlations between variables such as frequency of use and self-rated proficiency and performance in language tasks such as picture-naming accuracy (Edmonds & Donovan, 2012; Gollan et al. 2007), verbal fluency (Muñoz & Marquardt, 2008, Langdon et al., 2005; Elgamal et al., 2011), and discourse informativeness (Edmonds, 2013). In a study investigating discourse in 83 English/ Spanish bilingual adults, Edmonds (2013) reported varied patters of correlations for informativeness and efficiency measures (WPM, %CIUs, CIUs/min ) in English and Spanish. Naming accuracy and overall proficiency were significantly correlated with all measures of informativeness regardless of language; whereas, percent usage and age of exposure varied across languages (Edmonds, 2013). The metric of %CIU is often used to evaluate informativeness in discourse, but %CIU does not address the completeness of the discourse. I.e., one can achieve high %CIUs by providing correct information on half the picture, thus, targeting only half of the main concepts (MC). Alternatively, many MCs can be discussed with lower %CIU due to repetitions, circumlocutions and reformulations. In order to understand this dynamic better in bilinguals with varying degrees of proficiency across langauges, we adapted Nicholas and Brookshire’s (1993, 1995) MC analysis to this population. Our research questions were: 1) Is there a relationship (correlation) between %CIUs and MCs? 2) What self-reported participant variables (e.g., proficiency ratings, usage) and tested language variables (discourse variables, confrontation naming) correlate to English and Spanish MCs? 3) Of the significantly correlated variables, which contribute most to regression models of MCs in English and Spanish

Executive Attention deficits in aphasia: case studies

Many features of language impairments in people with aphasia (PWA) suggest that they have problems with executive functions that control language use (Hula and McNeil, 2008). An outstanding question is the extent to which the executive functions affected in PWA apply in other cognitive domains (Murray, 2012) or are specific to language (Jefferies and Lambon Ralph, 2006; Hoffman et al., 2013). The Executive Attention model (Engle and Kane, 2004) provides a framework for examining this question. It claims the central executive consists of two interacting components: task maintenance, the ability to use task goals to exert proactive control that reduces interference, and conflict resolution, the ability to resolve conflicts generated by interference during goal-directed processing. It is proposed that task maintenance is a domain-general capacity, and that conflict resolution is at least partially encapsulated, with specialized functions responsible for modality-specific interference. Therefore, PWA with task maintenance deficits should be affected in all cognitive areas, whereas PWA with conflict resolution impairments should be affected only in language functions, where they should show increased interference effects even in contexts of minimal task maintenance demand. Hypotheses were tested in two case studies

Verifying a Computational Model of Word Production with Voxel-based lesion-parameter Mapping

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