ABSTRACT
BACKGROUND AND OBJECTIVES: Nonverbal oral apraxia (NVOA) is the inability to plan, sequence, and execute voluntary oromotor movements in the absence of weakness. In the context of neurodegenerative disease, it remains unclear whether it is linked to a specific underlying pathologic, clinical, or neuroimaging finding. Thus, we aimed to assess the clinicopathologic and neuroimaging associations of NVOA. METHODS: We conducted a retrospective study of autopsy-confirmed patients previously assessed through an NVOA evaluation tool with a previously published cutpoint to screen for NVOA. We compared demographic and clinical characteristics and postmortem pathology between those who developed NVOA and those who did not. We also compared clinicopathologic characteristics in mild vs greater than mild NVOA and early vs late-emerging NVOA. SPM12 was used to assess patterns of gray matter loss in NVOA vs non-NVOA with age and sex included as covariates. RESULTS: A total of 104 patients (median age at symptom onset 63 years, 43% female) were included in the study. 63 (60.6%) developed NVOA. NVOA appeared at a median of 4.3 years from symptom onset. 29% developed NVOA within the first 3 years. Primary progressive apraxia of speech and the nonfluent variant of primary progressive aphasia were the most common baseline diagnoses in the NVOA group while progressive supranuclear palsy (PSP) syndrome and logopenic progressive aphasia (LPA) were the most common in patients without NVOA. Atrophy of the left lateral and medial posterior frontal cortex was related to NVOA. The most common pathologies associated with NVOA were PSP (36.5%) and corticobasal degeneration (CBD) (33.3%). In patients without NVOA, PSP (26.8%) and other pathologies (26.8%) were the most frequent. 11% of patients with NVOA had persistently mild NVOA and were more likely to have baseline diagnoses of LPA, PSP syndrome, or semantic dementia. The most frequent pathologies in this group were Alzheimer disease and PSP. The pathologic associations of greater than mild NVOA were CBD and PSP. DISCUSSION: NVOA is present in several clinical syndromes. It is most associated with PSP and CBD. NVOA is a manifestation of left lateral and medial posterior frontal cortex damage rather than a particular pathology.
Subject(s)
Apraxias , Neurodegenerative Diseases , Neuroimaging , Humans , Female , Male , Middle Aged , Apraxias/diagnostic imaging , Apraxias/etiology , Apraxias/pathology , Aged , Neurodegenerative Diseases/diagnostic imaging , Neurodegenerative Diseases/pathology , Retrospective Studies , Neuroimaging/methods , Magnetic Resonance Imaging , Brain/pathology , Brain/diagnostic imaging , Supranuclear Palsy, Progressive/diagnostic imaging , Supranuclear Palsy, Progressive/pathology , Supranuclear Palsy, Progressive/complicationsABSTRACT
Patients who have a yes-no reversal respond "yes" when they mean no and vice versa. The unintentional response can be made both verbally and with gestures (e.g., head shake or nod, thumbs up or down). Preliminary reports associate this phenomenon with 4-repeat tauopathies including primary progressive apraxia of speech (PPAOS), nonfluent/agrammatic primary progressive aphasia, and corticobasal syndrome; however, the significance and timing of this symptom relative to others are not well understood. Whereas some accounts associate yes-no reversals with other binary reversals (e.g., up/down, hot/cold) and attribute the reversals to disturbances of selection within the language system, others implicate more general inhibitory control processes. Here, we compared clinical and neuroimaging findings across 30 patients with PPAOS (apraxia of speech in the absence of aphasia), 15 of whom had a yes-no reversal complaint and 15 who did not. The two groups did not differ on any of the language or motor speech measures; however, patients who had the yes-no reversal received lower scores on the Frontal Assessment Battery and motor assessments. They also had greater hypometabolism in the left supplementary motor area and bilateral caudate nuclei on [18F]-fluorodeoxyglucose PET, but only the right caudate nucleus cluster survived correction for multiple comparisons. We interpret these results to suggest that the yes-no reversal phenomenon is associated with cognitive abilities that are supported by the frontostriatal network; more specifically, impaired response inhibition.
Subject(s)
Apraxias , Humans , Male , Female , Aged , Middle Aged , Apraxias/physiopathology , Speech/physiology , Positron-Emission Tomography , Neuropsychological Tests , Aphasia, Primary Progressive/physiopathology , Aphasia, Primary Progressive/diagnostic imaging , Magnetic Resonance Imaging , Brain/physiopathology , Brain/diagnostic imagingABSTRACT
PURPOSE: We describe the communication challenges of four patients with a neurodegenerative disorder consistent with behavioral variant frontotemporal dementia (bvFTD), characterized by early behavioral and personality changes. By describing their clinical profiles, we identify common barriers to functional communication in this population and provide recommendations for how speech-language pathologists (SLPs) might contribute to minimizing them. METHOD: Four patients with bvFTD were selected from a cohort of patients with progressive communication impairments. Three of them returned for at least one follow-up visit. Case histories are presented along with the results of comprehensive speech and language, neuropsychological, and neurological testing. RESULTS: At the time of initial evaluation, patients were between the ages of 54 and 66 years and had been experiencing symptoms for 1.5-6 years. Consistent with their bvFTD diagnoses, all patients had prominent behavioral and personality changes that impacted communication. Patients 1 and 2 also had mild aphasia at enrollment, primarily characterized by anomia and loss of word meaning. Patients 3 and 4 both had apraxia of speech and moderate-to-severe aphasia at enrollment with prominent anomia and agrammatism. All four patients had impaired executive functioning and relative sparing of visuospatial skills; episodic memory was also impaired for Patients 2 and 4. Even though functional communication was progressively limited for all patients, none of them received regular support from an SLP. CONCLUSIONS: This case series adds to a scant, but growing, literature demonstrating that patients with bvFTD have communication impairments. SLPs are uniquely positioned to identify barriers to functional communication and to provide tailored strategy training to the patients and their care partners over the course of their disease. Systematic evaluation of the efficacy of treatment in this population would be valuable. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.25933762.
Subject(s)
Frontotemporal Dementia , Neuropsychological Tests , Humans , Frontotemporal Dementia/psychology , Frontotemporal Dementia/diagnosis , Frontotemporal Dementia/therapy , Middle Aged , Aged , Male , Female , Aphasia/psychology , Aphasia/etiology , Aphasia/therapy , Communication Disorders/etiology , Communication Disorders/diagnosis , Communication Disorders/psychology , Communication Disorders/therapy , Speech-Language Pathology/methods , Executive Function , Language Tests , CommunicationABSTRACT
Objectives: To introduce the first case in which primary progressive apraxia of speech (PPAOS) is associated with TAR DNA-binding protein 43 (TDP-43) instead of 4-repeat tau. Methods: This patient was identified through a postmortem autopsy. Following an initial diagnostic evaluation, he participated in 3 annual research visits during which speech, language, cognitive, and neurologic assessments were administered. Neuroimaging was also acquired. Results: Apraxia of speech was diagnosed at his initial visit with a comprehensive neurologic examination further revealing subtle motor findings in the right hand. At subsequent visits, agrammatic aphasia and motor symptoms consistent with corticobasal syndrome were evident. Cognition and behavior remained relatively intact until advanced stages. FDG-PET revealed hypometabolism in the right temporoparietal cortex and left premotor and motor cortices. There was also low-level signal in the right temporoparietal cortex on tau-PET. A sequence variation in the progranulin gene was identified (GRN c.1A>C, p.Met1). Pathologic diagnosis was TDP-43 Type A with an atypical distribution of inclusions in premotor and motor cortices. Discussion: This case report demonstrates that TDP-43 Type A inclusions in an atypical distribution can present clinically as PPAOS. The sequence variation in the progranulin gene and asymmetric temporoparietal cortex involvement were the strongest indications of the unusual neuropathophysiology prior to autopsy.
ABSTRACT
BACKGROUND: Progressive apraxia of speech (PAOS) is characterized by difficulties with motor speech programming and planning. PAOS targets gray matter (GM) and white matter (WM) microstructure that can be assessed using diffusion tensor imaging (DTI) and multishell applications, such as neurite orientation dispersion and density imaging (NODDI). In this study, we aimed to apply DTI and NODDI to add further insight into PAOS tissue microstructure. METHODS: Twenty-two PAOS patients and 26 age- and sex-matched controls, recruited by the Neurodegenerative Research Group (NRG) at Mayo Clinic, underwent diffusion MRI on 3T MRI. Brain maps of fractional anisotropy (FA) and mean diffusivity (MD) from DTI and intracellular volume fraction (ICVF) and isotropic volume fraction (IsoVF) from NODDI were generated. Global WM and GM, and specific WM tracts were identified using tractography and lobar GM regions. RESULTS: Global WM differences between PAOS and controls were greatest for ICVF, and global GM differences were greatest for MD and IsoVF. Abnormalities in key WM tracts involved in PAOS, including the body of the corpus callosum and frontal aslant tract, were identified with FA, MD, and ICVF, with excellent differentiation of PAOS from controls (area under the receiver operating characteristic curves >.90). MD and ICVF identified abnormalities in arcuate fasciculus, thalamic radiations, and corticostriatal tracts. Significant correlations were identified between an index of articulatory errors and DTI and NODDI metrics from the arcuate fasciculus, frontal aslant tract, and inferior longitudinal fasciculus. CONCLUSIONS: DTI and NODDI represent different aspects of brain tissue microstructure, increasing the number of potential biomarkers for PAOS.
Subject(s)
Apraxias , White Matter , Humans , Diffusion Tensor Imaging/methods , Neurites , Speech , Brain/diagnostic imaging , Diffusion Magnetic Resonance Imaging/methods , White Matter/diagnostic imagingABSTRACT
Most recent studies of progressive apraxia of speech (PAOS) have focused on patients with phonetic or prosodic predominant PAOS to understand the implications of the presenting clinical phenotype. Patients without a clearly predominating speech quality, or mixed AOS, have been excluded. Given the implications for disease progression, it is important to understand these patients early in the disease course to inform appropriate education and prognostication. The aim of this study was to describe a cohort of ten patients with initially mixed PAOS and how their clinical course evolves. Four patients were rated prosodic predominant later on (mild AOS at first visit); five were later designated phonetic (four with more than mild AOS at first visit); one was judged mixed at all visits. The study suggests patients without a clear predominance of speech featuresshould still be included in PAOS studies and thought of on the continuum of the disease spectrum.
ABSTRACT
Form priming has been used to identify and demarcate the processes that underlie word and sign recognition. The facilitation that results from the prime and target being related in form is typically interpreted in terms of pre-activation of linguistic representations, with little to no consideration for the potential contributions of increased perceptual overlap between related pairs. Indeed, isolating the contribution of perceptual similarity is impossible in spoken languages; there are no listeners who can perceive speech but have not acquired a sound-based phonological system. Here, we compared the electrophysiological indices of form priming effects in American Sign Language between hearing non-signers (i.e., who had no visual-manual phonological system) and deaf signers. We reasoned that similarities in priming effects between groups would most likely be perceptual in nature, whereas priming effects that are specific to the signer group would reflect pre-activation of phonological representations. Behavior in the go/no-go repetition detection task was remarkably similar between groups. Priming in a pre-N400 window was also largely similar across groups, consistent with an early effect of perceptual similarity. However, priming effects diverged between groups during the subsequent N400 and post-N400 windows. Signers had more typical form priming effects and were especially attuned to handshape overlap, whereas non-signers did not exhibit an N400 component and were more sensitive to location overlap. We attribute this pattern to an interplay between perceptual similarity and phonological knowledge. Perceptual similarity contributes to early phonological priming effects, while phonological knowledge tunes sensitivity to linguistically relevant dimensions of perceptual similarity.
Subject(s)
Electroencephalography , Sign Language , Evoked Potentials/physiology , Female , Humans , Linguistics , Male , Recognition, PsychologyABSTRACT
The picture word interference (PWI) paradigm and ERPs were used to investigate whether lexical selection in deaf and hearing ASL-English bilinguals occurs via lexical competition or whether the response exclusion hypothesis (REH) for PWI effects is supported. The REH predicts that semantic interference should not occur for bimodal bilinguals because sign and word responses do not compete within an output buffer. Bimodal bilinguals named pictures in ASL, preceded by either a translation equivalent, semantically-related, or unrelated English written word. In both the translation and semantically-related conditions bimodal bilinguals showed facilitation effects: reduced RTs and N400 amplitudes for related compared to unrelated prime conditions. We also observed an unexpected focal left anterior positivity that was stronger in the translation condition, which we speculate may be due to articulatory priming. Overall, the results support the REH and models of bilingual language production that assume lexical selection occurs without competition between languages.
ABSTRACT
It is currently unclear to what degree language control, which minimizes non-target language interference and increases the probability of selecting target-language words, is similar for sign-speech (bimodal) bilinguals and spoken language (unimodal) bilinguals. To further investigate the nature of language control processes in bimodal bilinguals, we conducted the first event-related potential (ERP) language switching study with hearing American Sign Language (ASL)-English bilinguals. The results showed a pattern that has not been observed in any unimodal language switching study: a switch-related positivity over anterior sites and a switch-related negativity over posterior sites during ASL production in both early and late time windows. No such pattern was found during English production. We interpret these results as evidence that bimodal bilinguals uniquely engage language control at the level of output modalities.
Subject(s)
Multilingualism , Evoked Potentials , Humans , Language , Sign Language , SpeechABSTRACT
We used transposed-letter (TL) priming to test the lexical tuning hypothesis, which states that words from high-density orthographic neighborhoods have more precise orthographic codes than words from low-density neighborhoods. Replicating standard TL priming effects, target words elicited faster lexical decision responses and smaller amplitude N250s and N400s when preceded by TL primes (e.g., leomn-LEMON) compared with substitution primes (e.g., leuzn-LEMON) overall. We expected that if high-density words have more precise orthographic representations (i.e., with each letter assigned to a specific position), then they should be relatively less activated by TL primes and should give rise to smaller TL priming effects. In line with our prediction, N250 (but not N400 or behavioral) TL priming was significantly smaller for high-density words compared with low-density words over posterior sites. Such an interaction was not observed for pseudoword targets. Consistent with the lexical tuning hypothesis then, this pattern suggests that the nature of the orthographic code used to access lexical representations differs depending on the number of neighboring words in the lexicon. We conclude by discussing how lexical tuning could be implemented in current models of orthographic processing.
Subject(s)
Motor Activity , Reading , Humans , Pattern Recognition, Visual , Perceptual Masking , Reaction TimeABSTRACT
The extent to which higher-order representations can be extracted from more than one word in parallel remains an unresolved issue with theoretical import. Here, we used ERPs to investigate the timing with which semantic information is extracted from parafoveal words. Participants saw animal and non-animal targets paired with response congruent or incongruent flankers in a semantic categorization task. Animal targets elicited smaller amplitude negativities when they were paired with semantically related and response congruent animal flankers (e.g., wolf coyote wolf) compared to unrelated and response incongruent flankers (e.g., sock coyote sock) in the N400 window and a post-N400 window. We interpret the N400 effect in terms of facilitated processing from the joint activation of shared semantic features (e.g., animal, furry) across target and flanker words and the later effect in terms of post-lexical decision-making. Thus, semantic information can be extracted from flankers in parallel and impacts various stages of processing.
Subject(s)
Evoked Potentials , Semantics , Electroencephalography , Female , Humans , MaleABSTRACT
We used phonological priming and ERPs to investigate the organization of the lexicon in American Sign Language. Across go/no-go repetition detection and semantic categorization tasks, targets in related pairs that shared handshape and location elicited smaller N400s than targets in unrelated pairs, indicative of facilitated processing. Handshape-related targets also elicited smaller N400s than unrelated targets, but only in the repetition task. The location priming effect reversed direction across tasks, with slightlylargeramplitude N400s for targets in related versus unrelated pairs in the semantic task, indicative of interference. These patterns imply that handshape and location play different roles during sign recognition and that there is a hierarchical organization for the sign lexicon. Similar to interactive-activation models of word recognition, we argue for differentiation between sublexical facilitation and lexical competition. Lexical competition is primarily driven by the location parameter and is more engaged when identification of single lexico-semantic entries is required.
Subject(s)
Linguistics , Sign Language , Evoked Potentials , Humans , Recognition, Psychology , Semantics , United StatesABSTRACT
Models of visual word recognition differ as to how print exposure modulates orthographic precision. In some models, precision is the optimal end state of a lexical representation; the associations between letters and positions are initially approximate and become more precise as readers gain exposure to the word. In others, flexible orthographic coding that allows for rapid access to semantics (i.e., 'good enough' orthographic processing) is the optimal end state. To adjudicate between these trajectories, we compared the size of transposed-letter ERP priming effects on two ERP components thought to reflect orthographic and lexico-semantic processing across languages in late English-Spanish bilinguals. Words that are represented precisely should be less susceptible to activation by transposed-letter primes (e.g., shpae-SHAPE) than words that are not, and should therefore yield smaller priming effects. Overall, targets elicited smaller N250s and N400s and faster responses when preceded by transposed-letter primes compared to substitution primes (e.g., shgue-SHAPE). The only effect that significantly differed between languages was N400 priming, which was larger in English, the dominant language. We suggest that these results favor models of learning to read according to which 'good enough' orthographic processing increases with print exposure.
ABSTRACT
Models vary in the extent to which language control processes are domain general. Those that posit that language control is at least partially domain general insist on an overlap between language control and executive control at the goal level. To further probe whether or not language control is domain general, we conducted the first event-related potential (ERP) study that directly compares language-switch costs, as an index of language control, and task-switch costs, as an index of executive control. The language switching and task switching methodologies were identical, except that the former required switching between languages (English or Spanish) whereas the latter required switching between tasks (color naming or category naming). This design allowed us to directly compare control processes at the goal level (cue-locked ERPs) and at the task performance level (picture-locked ERPs). We found no significant differences in the switch-related cue-locked and picture-locked ERP patterns across the language and task switching paradigms. These results support models of domain-general language control.
ABSTRACT
Phonology is often assumed to play a role in the tuning of orthographic representations, but it is unknown whether deaf readers' reduced access to spoken phonology reduces orthographic precision. To index how precisely deaf and hearing readers encode orthographic information, we used a masked transposed-letter (TL) priming paradigm. Word targets were preceded by TL primes formed by reversing two letters in the word and substitution primes in which the same two letters were replaced. The two letters that were manipulated were either in adjacent or non-adjacent positions, yielding four prime conditions: adjacent TL (e.g., chikcen-CHICKEN), adjacent substitution (e.g., chidven- CHICKEN), non-adjacent TL (e.g., ckichen-CHICKEN), and non-adjacent substitution (e.g., cticfen-CHICKEN). Replicating the standard TL priming effects, targets preceded by TL primes elicited smaller amplitude negativities and faster responses than those preceded by substitution primes overall. This indicates some degree of flexibility in the associations between letters and their positions within words. More flexible (i.e., less precise) representations are thought to be more susceptible to activation by TL primes, resulting in larger TL priming effects. However, the size of the TL priming effects was virtually identical between groups. Moreover, the ERP effects were shifted in time such that the adjacent TL priming effect arose earlier than the non-adjacent TL priming effect in both groups. These results suggest that phonological tuning is not required to represent orthographic information in a precise manner.
Subject(s)
Deafness/physiopathology , Evoked Potentials , Hearing/physiology , Linguistics , Reading , Adult , Female , Humans , Male , Reaction Time , RotationABSTRACT
Are syntactic representations shared across languages, and how might that inform the nature of syntactic computations? To investigate these issues, we presented French-English bilinguals with mixed-language word sequences for 200 ms and asked them to report the identity of one word at a post-cued location. The words either formed an interpretable grammatical sequence via shared syntax (e.g., ses feet sont big - where the French words ses and sont translate into his and are, respectively) or an ungrammatical sequence with the same words (e.g., sont feet ses big). Word identification was significantly greater in the grammatical sequences - a bilingual sentence superiority effect. These results not only provide support for shared syntax, but also reveal a fascinating ability of bilinguals to simultaneously connect words from their two languages through these shared syntactic representations.
Subject(s)
Language , Multilingualism , Cues , Female , Humans , Male , Reaction Time , Young AdultABSTRACT
Throughout their lifetime, adults learn new words in their native lannguage, and potentially also in a second language. However, they do so with variable levels of success. In the auditory word learning literature, some of this variability has been attributed to phonological skills, including decoding and phonological short-term memory. Here I examine how the relationship between phonological skills and word learning applies to the visual modality. I define the availability of phonology in terms of (1) the extent to which it is biased by the learning environment, (2) the characteristics of the words to be learned, and (3) individual differences in phonological skills. Across these three areas of research, visual word learning improves when phonology is made more available to adult learners, suggesting that phonology can facilitate learning across modalities. However, the facilitation is largely specific to alphabetic languages, which have predictable sublexical correspondences between orthography and phonology. Therefore, I propose that phonology bootstraps visual word learning by providing a secondary code that constrains and refines developing orthographic representations.
Subject(s)
Attention , Language , Learning , Phonetics , Adult , Humans , Reading , Spatial Learning , Verbal LearningABSTRACT
In masked priming studies with hearing readers, neighbouring words (e.g., wine, vine) compete through lateral inhibition. Here, we asked whether lateral inhibition also characterizes visual word recognition in deaf readers and whether the neural signature of this competition is the same as for hearing readers. Only real words have lexical representations that engage in lateral inhibition. Therefore, we compared processing of target words following neighbouring prime words (e.g., wine-VINE) and pseudowords (e.g., bine-VINE). Targets following words elicited larger amplitude N400s and slower lexical decision responses than those following pseudowords, indicating more effortful processing due to lateral inhibition. Although these effects went in the same direction for hearing and deaf readers, the distribution of the N400 effect differed. We associate the more anterior effect in hearing readers with stronger co-activation of, and competition among, phonological representations. Thus, deaf readers use lexical competition to recognize visual words, but it is primarily restricted to orthographic representations.
ABSTRACT
Event-related potentials (ERPs) were used to investigate co-activation of English words during recognition of American Sign Language (ASL) signs. Deaf and hearing signers viewed pairs of ASL signs and judged their semantic relatedness. Half of the semantically unrelated signs had English translations that shared an orthographic and phonological rime (e.g., BAR-STAR) and half did not (e.g., NURSE-STAR). Classic N400 and behavioral semantic priming effects were observed in both groups. For hearing signers, targets in sign pairs with English rime translations elicited a smaller N400 compared to targets in pairs with unrelated English translations. In contrast, a reversed N400 effect was observed for deaf signers: target signs in English rime translation pairs elicited a larger N400 compared to targets in pairs with unrelated English translations. This reversed effect was overtaken by a later, more typical ERP priming effect for deaf signers who were aware of the manipulation. These findings provide evidence that implicit language co-activation in bimodal bilinguals is bidirectional. However, the distinct pattern of effects in deaf and hearing signers suggests that it may be modulated by differences in language proficiency and dominance as well as by asymmetric reliance on orthographic versus phonological representations.
ABSTRACT
During reading, word recognition speed is influenced by the amount of orthographic overlap with surrounding words. The nature of this phenomenon is not understood: some theories attribute it to low-level visual operations (i.e., parafoveal feature detectors influencing foveal letter detectors), whereas other theories assume that orthographic processing (i.e., letter position coding and word activation) occurs across multiple words in parallel. To arbitrate between these theories, we used electroencephalography to reveal the time course of orthographic spatial integration in a lexical decision task. Foveal target words were flanked on each side by parafoveal words, manipulated across three conditions: repetition flankers (e.g. rock rock rock), unrelated flankers (step rock step) and a no-flanker condition. Linear mixed-effect models were constructed to analyze EEG data on a trial-by-trial basis. Word recognition was worse in the unrelated flanker condition than in the repetition and no-flanker conditions. This behavioral pattern was accompanied by increased negativity in the N250 and N400 windows, associated with the activation of sub-lexical and lexico-semantic representations, respectively. Crucially, the absence of effects prior to 200â¯ms post-stimulus onset provides evidence against the involvement of low-level visual processes. We conclude that orthographic spatial integration is driven by parallel processing of multiple words, which leads to the activation of a larger set of sub-lexical nodes and more difficult processing at the lexical level when those words are orthographically unrelated.