Time course of evoked-potential changes in different forms of anomia in aphasia

No abstract available

Comparing Electrophysiological Correlates of Word Production in Immediate and Delayed Naming Through the Analysis of Word Age of Acquisition Effects

Most EEG studies analysing speech production with event related brain potential (ERP) have adopted silent metalinguistic tasks or delayed or tacit picture naming in order to avoid possible artefacts during motor preparation. A central issue in the interpretation of these results is whether the processes involved in those tasks are comparable to those involved in overt speech production. In the present study we addressed a methodological issue about the integration of stimulus-aligned and response-aligned ERPs in immediate overt picture naming in comparison to delayed production, coupled with a theoretical point on the effect of word Age of Acquisition (AoA). High density EEG recordings were used and waveform analyses and spatio-temporal segmentation were combined on stimulus-aligned and response-aligned ERPs. The same sequence and duration of topographic maps appeared in the immediate and delayed production until around 350ms after picture onset, revealing similar encoding processes until the beginning of phonological encoding, but modulations linked to word AoA were only observed in the immediate production. Considering stimulus-aligned and response-aligned ERPs together allowed to identify that a stable topography starting around 350ms lasts 30ms longer for late-acquired than for early-acquired words. This difference falls within the time-window of phonological encoding and its modulation can be linked to the longer production latencies for late-acquired word

ERP correlates of word production before and after stroke in an aphasic patient

No abstract available

Re-evaluating the Time Course of Gender and Phonological Encoding During Silent Monitoring Tasks Estimated by ERP: Serial or Parallel Processing?

Neurolinguistic and psycholinguistic studies suggest that grammatical (gender) and phonological information are retrieved independently and that gender can be accessed before phonological information. This study investigated the relative time courses of gender and phonological encoding using topographic evoked potentials mapping methods. Event-related brain potentials (ERPs) were recorded using a high resolution electroencephalogram (EEG) system (128 channels) during gender and phoneme monitoring in silent picture naming. Behavioural results showed similar reaction times (RT) between gender and word onset (first phoneme) monitoring, and longer RT when monitoring the second syllable onset. Temporal segmentation analysis (defining dominant map topographies using cluster analysis) revealed no timing difference between gender monitoring and word onset monitoring: both effects fall within the same time window at about 270-290ms after picture presentation. Monitoring a second syllable onset generated a later effect at about 480ms. Direct comparison between gender and first phoneme monitoring revealed a difference of only 10ms between tasks at approximately 200ms. Taken together, these results suggest that lemma retrieval and phonological encoding may proceed in parallel or overlap. Word onset is retrieved simultaneously with gender, while the longer RT and the later ERP effect for second syllable onset reflect that segmental encoding continues incrementally to the following phoneme

Language specificity of lexical-phonological therapy in bilingual aphasia: A clinical and electrophysiological study

Based on findings for overlapping representations of bilingual people's first (L1) and second (L2) languages, unilingual therapies of bilingual aphasia have been proposed to benefit the untrained language. However, the generalisation patterns of intra- and cross-language and phonological therapy and their neural bases remain unclear. We tested whether the effects of an intensive lexical-phonological training (LPT) in L2 transferred to L1 word production in a Persian-French bilingual stroke patient with Broca's aphasia. Language performance was assessed using the Bilingual Aphasia Test, a 144-item picture naming (PN) task and a word–picture verification (WPV) task. Electroencephalography (EEG) was recorded during PN and WPV in both languages before and after an LPT in French on a wordlist from the PN task. After the therapy, naming improved only for the treated L2 items. The naming performance improved neither in the untrained L2 items nor in the corresponding items in L1. EEG analyses revealed a Language x Session topographic interaction at 540 ms post-stimulus, driven by a modification of the electrophysiological response to the treated L2 but not L1 items. These results indicate that LPT modified the brain networks engaged in the phonological-phonetic processing during naming only in the trained language for the trained items

Logopenic and nonfluent variants of primary progressive aphasia are differentiated by acoustic measures of speech production

Differentiation of logopenic (lvPPA) and nonfluent/agrammatic (nfvPPA) variants of Primary Progressive Aphasia is important yet remains challenging since it hinges on expert based evaluation of speech and language production. In this study acoustic measures of speech in conjunction with voxel-based morphometry were used to determine the success of the measures as an adjunct to diagnosis and to explore the neural basis of apraxia of speech in nfvPPA. Forty-one patients (21 lvPPA, 20 nfvPPA) were recruited from a consecutive sample with suspected frontotemporal dementia. Patients were diagnosed using the current gold-standard of expert perceptual judgment, based on presence/absence of particular speech features during speaking tasks. Seventeen healthy age-matched adults served as controls. MRI scans were available for 11 control and 37 PPA cases; 23 of the PPA cases underwent amyloid ligand PET imaging. Measures, corresponding to perceptual features of apraxia of speech, were periods of silence during reading and relative vowel duration and intensity in polysyllable word repetition. Discriminant function analyses revealed that a measure of relative vowel duration differentiated nfvPPA cases from both control and lvPPA cases (r2 = 0.47) with 88% agreement with expert judgment of presence of apraxia of speech in nfvPPA cases. VBM analysis showed that relative vowel duration covaried with grey matter intensity in areas critical for speech motor planning and programming: precentral gyrus, supplementary motor area and inferior frontal gyrus bilaterally, only affected in the nfvPPA group. This bilateral involvement of frontal speech networks in nfvPPA potentially affects access to compensatory mechanisms involving right hemisphere homologues. Measures of silences during reading also discriminated the PPA and control groups, but did not increase predictive accuracy. Findings suggest that a measure of relative vowel duration from of a polysyllable word repetition task may be sufficient for detecting most cases of apraxia of speech and distinguishing between nfvPPA and lvPPA

The modulation of reading strategies by language opacity in early bilinguals: an eye movement study

Converging evidences from eye movement experiments indicate that linguistic contexts influence reading strategies. However, the question of whether different linguistic contexts modulate eye movements during reading in the same bilingual individuals remains unresolved. We examined reading strategies in a transparent (German) and an opaque (French) language of early, highly proficient French–German bilinguals: participants read aloud isolated French and German words and pseudo- words while the First Fixation Location (FFL), its duration and latency were measured. Since transparent linguistic contexts and pseudo-words would favour a direct grapheme/phoneme conversion, the reading strategy should be more local for German than for French words (FFL closer to the beginning) and no difference is expected in pseudo-words’ FFL between contexts. Our results confirm these hypotheses, providing the first evidence that the same individuals engage different reading strategy depending on language opacity, suggesting that a given brain process can be modulated by a given context

Technology Enhanced Writing Therapy for People with Aphasia: Results of a Quasi-Randomised Waitlist Controlled Study

Background: Acquired writing impairment, or dysgraphia, is common in aphasia. It affects both handwriting and typing, and may recover less well than other aphasic symptoms. Dysgraphia is an increasing priority for intervention, particularly for those wishing to participate in online written communication. Effective dysgraphia treatment studies have been reported, but many did not target, or did not achieve, improvements in functional writing. Functional outcomes might be promoted by therapies that exploit digital technologies, such as voice recognition and word prediction software. Aims: This study evaluated the benefits of technology enhanced writing therapy for people with acquired dysgraphia. It aimed to explore the impact of therapy on a functional writing activity, and to examine whether treatment remediated or compensated for the writing impairment. The primary question was: Does therapy improve performance on a functional assessment of writing; and, if so, do gains occur only when writing is assisted by technology? Secondary measures examined whether therapy improved unassisted written naming, functional communication, mood and quality of life. Methods & Procedures: The study employed a quasi randomised waitlist controlled design. 21 people with dysgraphia received 12 hours of writing therapy, either immediately, or after a 6 week delay. The primary outcome measure was a functional assessment of writing, which was administered in handwriting and on a computer with assistive technology enabled. Secondary measures were: The Boston Naming Test (written version), Communication Activities of Daily Living - 2, Visual Analogue Mood Scales (Sad question), and the Assessment of Living with Aphasia. ANOVA analyses were used to examine change on the outcome measures over two time points, between which the immediate group had received therapy, but the delayed group had not. Pre therapy, post therapy and follow up scores on the measures were also examined for all participants. Outcomes & Results: Time x group interactions in the ANOVA analyses showed that therapy improved performance on the functional writing assessment. Further interactions with condition showed that gains occurred only when writing was assisted by technology. There were no significant interactions in the analyses of the secondary outcome measures. A treatment effect on these measures was therefore unconfirmed. Conclusions & Implications. This study showed that 21 people with dysgraphia improved on a functional writing measure following therapy using assistive technology. The results suggest that treatment compensated for, rather than remediated the impairment, given that unassisted writing did not change. Further studies of technology enhanced writing therapy are warranted. What this paper adds What is known already: Writing abilities are typically impaired in aphasia, and may recover less well than other language modalities. Many previous writing therapy studies did not achieve functional gains on everyday writing tasks. What this study adds: This study shows that mainstream digital technologies, such as speech to text software, can be used in therapy to help compensate for writing impairments. Gains were shown on a functional task (writing emails) after 12 hours of treatment. Clinical implications: With specific training, people with aphasia can learn to use mainstream technologies in order to support writing. Greater use of such technologies could be made in practice

PAoS Markers: Trajectory Analysis of Selective Phonological Posteriors for Assessment of Progressive Apraxia of Speech

Progressive apraxia of Speech (PAoS) is a progressive motor speech disorder associated with neurodegenerative disease causing impairment of phonetic encoding and motor speech planning. Clinical observation and acoustic studies show that duration analysis provides reliable cues for diagnosis of the disease progression and severity of articulatory disruption. The goal of this paper is to develop computational methods for objective evaluation of duration and trajectory of speech articulation. We use phonological posteriors as speech features. Phonological posteriors consist of probabilities of phonological classes estimated for every short segment of the speech signal. PAoS encompasses lengthening of duration which is more pronounced in vowels; we thus hypothesize that a small subset of phonological classes provide stronger evidence for duration and trajectory analysis. These classes are determined through analysis of linear prediction coefficients (LPC). To enable trajectory analysis without phonetic alignment, we exploit phonological structures defined through quantization of phonological posteriors. Duration and trajectory analysis are conducted on blocks of multiple consecutive segments possessing similar phonological structures. Moreover, unique phonological structures are identified for every severity condition

Prefixes repel stress in reading aloud: Evidence from surface dyslexia

This study examined the importance of prefixes as sublexical cues for stress assignment during reading aloud English disyllabic words. In particular, we tested the hypothesis that prefixes repel stress (Rastle & Coltheart, 2000) by investigating the likelihood with which patients with surface dyslexia assign second-syllable stress to prefixed words. Five such patients were presented with three types of disyllabic words for reading aloud: 'regular' prefixed words with weak-strong stress pattern (e.g., remind); 'irregular' prefixed words with strong-weak stress pattern (e.g., reflex); and non-prefixed words with strong-weak stress pattern (e.g., scandal). Results showed that all five patients frequently regularized the strong-weak prefixed words by pronouncing them with second syllable stress. These regularization errors provide strong evidence for the functional role of prefixes in stress assignment during reading. Additional computational simulations using the rule-based algorithm for pronouncing disyllables developed by Rastle and Coltheart (2000) and the CDP++ model of reading aloud (Perry et al., 2010) allowed us to evaluate how these two opponent approaches to reading aloud fare in respect of the patient data.15 page(s