Aging effects and working memory in garden-path sentence comprehension

The current study examined whether older adults exhibit difficulty in recovering from syntactically ambiguous garden-path sentences, and whether this difficulty is predicted by working memory capacity (WM). This study found several points. First, there was a garden-path effect regardless of age group. Second, there were age-related differences between young and elderly adults for the sentences with temporary syntactic ambiguity, in on- and off-line measures. Third, the age-related effects were predicted by WM. These points indicate that syntactic ambiguity resolution is affected by healthy cognitive aging, and suggest that age-related WM changes may be responsible for these differences

The inner workings of working memory: Preliminary data from unimpaired populations

Wright et al. (2007) tested Persons With Aphasia (PWA) using three N-Back tasks featuring different types of linguistic information – phonological, semantic, and syntactic -- to determine whether Verbal Working Memory (VWM) is a single, united resource.  The current study tested two groups of cognitively normal individuals with the same tasks, as well as an additional vision-focused task, to expand on this previous research and provide a baseline for future studies of WM in PWA.  Results indicated no effects of aging outside of Reaction Times, and significant differences in performance across all types of information except phonological and visual cues

Acquisition and generalization responses in aphasia treatment: Evidence from sentence-production treatment

Treatment of Underlying Forms (TUF) promotes not only acquisition of treated sentence types but also generalization to related but untreated sentences (e.g., Thompson, Shapiro, Kiran & Sobecks, 2003). In a meta-analysis examining TUF treatment outcomes, Dickey and Yoo (2010) found evidence that the factors governing TUF acquisition and generalization may be different. They found that general auditory comprehension ability but not overall aphasia severity or sentence-comprehension impairment predicted participants’ acquisition of treated sentences. In contrast, none of these factors were related to participants’ generalization to related but untreated sentences. Interestingly, Meinzer and colleagues (2010) found similar results for naming treatment: brain areas that were positively related to acquiring treated items were not associated with generalization to untreated words. These findings suggest that the mechanisms responsible for acquisition and generalization responses to aphasia treatment may be distinct. The current study examined this question further by testing the dose-response relationships for TUF, for both acquisition and generalization. It analyzed existing TUF treatment studies by using multilevel generalized linear regression to model changes in probe accuracy over the course of treatment. One model estimated the slope and intercept of acquisition and generalization curves in response to increasing amounts of treatment. A second set of models tested whether these dose-response relationships were moderated by aphasia severity (viz. Dickey & Yoo, 2010). Determining whether acquisition and generalization curves exhibit similar slopes and intercepts, and whether they are moderated by the same factors, will help establish how similar the two treatment responses are. Comparing the slopes and intercepts of these curves can also shed light on whether similar amounts of treatment are needed to promote acquisition and generalization

The functional relation between syntactic and morphological recovery in aphasia: A case study

Morphological and syntactic impairments often co-occur in aphasia. Whether they are causally related is an issue of long-standing debate. This paper reports a case study of one individual with such impairments and describes their recovery in response to linguistically-motivated treatment. CL is a 56 year-old male with Broca's aphasia and limited capacity to produce syntactically complex utterances or grammatical morphology. He was enrolled in the Treatment of Underlying Forms protocol (Thompson, 2001). CL acquired production of Wh- questions, indicating improved access to CP, but his production of CP-related morphology declined. These patterns indicate that the recovery of syntactic and morphological processes in aphasia are at least partially independent

Examining cortical tracking of the speech envelope in post-stroke aphasia

IntroductionPeople with aphasia have been shown to benefit from rhythmic elements for language production during aphasia rehabilitation. However, it is unknown whether rhythmic processing is associated with such benefits. Cortical tracking of the speech envelope (CTenv) may provide a measure of encoding of speech rhythmic properties and serve as a predictor of candidacy for rhythm-based aphasia interventions.MethodsElectroencephalography was used to capture electrophysiological responses while Spanish speakers with aphasia (n = 9) listened to a continuous speech narrative (audiobook). The Temporal Response Function was used to estimate CTenv in the delta (associated with word- and phrase-level properties), theta (syllable-level properties), and alpha bands (attention-related properties). CTenv estimates were used to predict aphasia severity, performance in rhythmic perception and production tasks, and treatment response in a sentence-level rhythm-based intervention.ResultsCTenv in delta and theta, but not alpha, predicted aphasia severity. Neither CTenv in delta, alpha, or theta bands predicted performance in rhythmic perception or production tasks. Some evidence supported that CTenv in theta could predict sentence-level learning in aphasia, but alpha and delta did not.ConclusionCTenv of the syllable-level properties was relatively preserved in individuals with less language impairment. In contrast, higher encoding of word- and phrase-level properties was relatively impaired and was predictive of more severe language impairments. CTenv and treatment response to sentence-level rhythm-based interventions need to be further investigated