Kristie A. Spencer

Speech motor programming in hypokinetic and ataxic dysarthria

It is widely accepted that the cerebellar and basal ganglia control circuits contribute to the programming of movement. Converging evidence from neuroimaging, limb control, and neuropsychological studies suggests that (1) people with cerebellar disease have reduced ability to program movement sequences in advance of movement onset and (2) people with Parkinsons disease are unable to maintain a programmed response or to rapidly switch between responses. Despite a substantial supporting literature, no studies have addressed these potential areas of speech programming disruption for speakers with ataxic and hypokinetic dysarthria. Control participants and adults with dysarthria completed speech reaction time protocols designed to capture these aspects of utterance preparation. Results provided initial support for processing deficits in speakers with ataxic and hypokinetic dysarthria that are separable from motor execution impairments.

The neural basis of ataxic dysarthria

Lesions to the cerebellum often give rise to ataxic dysarthria which is characterized by a primary disruption to articulation and prosody. Converging evidence supports the likelihood of speech motor programming abnormalities in addition to speech execution deficits. The understanding of ataxic dysarthria has been further refined by the development of neural network models and neuroimaging studies. A critical role of feedforward processing by the cerebellum has been established and linked to speech motor control and to aspects of ataxic dysarthria. Moreover, this research has helped to define models of the cerebellar contributions to speech processing and production, and to posit possible regions of speech localization within the cerebellum. Bilateral, superior areas of the cerebellum appear to mediate speech motor control while a putative role of the right cerebellar hemispheres in the planning and processing of speech has been suggested.

Do principles of motor learning enhance retention and transfer of speech skills? A systematic review

Background: It is well documented in limb motor research that providing the optimal practice and feedback conditions can have positive outcomes for the learning of new movements. However, it remains unclear if the training conditions used for limb movements can be directly applied to the speech motor system of healthy adults and individuals with acquired motor speech disorders. Collectively these practice and feedback conditions are known as the principles of motor learning (PML), and they have recently been applied to the rehabilitation of motor speech disorders with promising results. Aims: The purpose of this systematic review is to identify which PML have been examined in the speech motor learning literature, to determine the effectiveness of these principles, and to ascertain future lines of research. Methods & Procedures: A systematic search of the literature was completed that involved the combination of a primary search term with a secondary search term. All articles were independently reviewed and scored by the first two authors. To guide the selection process strict inclusion and exclusion criteria were implemented. Additionally, authors used a 15-category evidence-rating system to judge the overall quality of each study. After the study was scored, points were totalled into an overall quality rating of high, intermediate, or low with respect to methodological rigour and interpretability. Outcomes & Results: Seven articles met inclusion criteria, including three randomised controlled trials and four single-participant designs. Five of the articles focused on motor speech disorders, including investigations of apraxia of speech (four studies) and hypokinetic dysarthria from Parkinsons disease (one study), while two studies focused on speech motor performance in healthy adults. Five of the articles were judged to be of high quality while two were judged to be of intermediate quality. Conclusions: Although limited, the current level of evidence for the application of the PML to speech motor learning in both healthy adults and individuals with motor speech disorders is promising and continued investigation is warranted.

The Communicative Informativeness and Efficiency of Connected Discourse by Adults With Aphasia Under Structured and Conversational Sampling Conditions

Measuring communicative informativeness under conversational discourse conditions is perhaps the most valid means of determining the interpersonal verbal communication abilities of adults with apha...

A double-blind, placebo-controlled study of pharmacological and behavioural treatment of lexical-semantic deficits in aphasia

This investigation replicated and extended an earlier study of naming disorders (McNeil. et al. 1995) by administering a placebo and pharmacological agents (d-amphetamine and selegiline) in the presence and absence of a behavioural intervention termed lexical-semantic activation inhibition therapy (L-SAIT) to examine their effects on naming performance in two adults with stroke-induced aphasia. Results revealed acquisition and maintenance effects of L-SAIT on targeted lexical items, no effects of placebo or active pharmacological agents in the absence of L-SAIT, and no differential effects between placebo + L-SAIT and pharmacological agents + L-SAIT. Thus, positive treatment effects were attributed to L-SAIT. Generalization to untrained items within and across form class was not observed, nor was generalization to measures of informativeness of connected speech. Subject 1 evidenced improvement on the Rapid Automatized Naming Test (Denckla and Rudel 1976).

Linguistic validation of four parallel forms of a story retelling procedure

This study reports the development and validation of four parallel forms of a story retelling procedure. The equivalency of forms was based on the performance of 15 adults with aphasia on 12 operationally defined productive language variables including measures of (a) verbal productivity, (b) information content, (c) grammatical well-formedness, (d) phoneme production, and (e) verbal disruptions. The results revealed no significant differences among the four forms of the test for any of the dependent measures, and strong, positive and significant correlations among forms for 11 of the 12 dependent measures. These results suggest that a wide variety of productive language variables can be reliably measured using parallel forms of the story-retelling procedure described herein.

Effects of training multiple form classes on acquisition, generalization and maintenance of word retrieval in a single subject

A study by McNeil et nl. reported no generalization effects in two individuals with aphasia following application of a word finding treatment in which subjects were trained sequentially on lexical items arranged by form class. The present investigation examined, in one of the two subjects from the original study, whether training on lexical items from a variety of form classes concurrently would result in greater response generalization than was observed previously in this subject. Results replicated earlier findings with positive acquisition and maintenance effects and little evidence of generalization to untrained items within or across form classes.

Examining the facilitative effects of rhyme in a patient with output lexicon damage

A theory-driven treatment was designed to facilitate access to the impaired output lexicons of a 47-year-old woman with aphasia resulting from a left parietal haemorrhage. In the context of a multiple-baseline design, lists of rhymed word pairs from four semantic categories were trained using a systematic cueing hierarchy. Performance measures were based on the subjects generation of targeted words, verbally and in writing, when presented with a rhyme of the target. Results demonstrated positive acquisition, generalization and maintenance effects for treated and untreated items across semantic categories. Delayed generalization patterns may be explained by retrieval inhibition (Blaxton and Bookheimer 1993) or lateral inhibition (McClelland and Rumelhart 1981).

Response priming patterns differ with interstimulus interval duration

Priming paradigms make it possible to study the nature of response preparation before the onset of movement. One way to examine this process is through manipulation of the interstimulus interval (ISI). The timing of the prime and target presentation has been shown to have distinct effects on reaction time patterns, in both healthy and neurologically impaired individuals, during cognitive task switching paradigms and semantic priming studies. What is unclear, however, are the effects of ISI durations on response priming paradigms. In the present study, ISIs of five durations were manipulated within a speech response priming paradigm to investigate reaction time patterns in 25 healthy adults. Results suggested that ISIs have a significant influence on the magnitude of the priming effect. Brief ISIs, with a putatively high sensitivity to reprogramming, resulted in robust priming effects. Long ISIs, thought to be influenced by attentional factors, resulted in priming effects of lesser magnitude.

Intentional and Reactive Inhibition During Spoken-Word Stroop Task Performance in People With Aphasia

PURPOSE The integrity of selective attention in people with aphasia (PWA) is currently unknown. Selective attention is essential for everyday communication, and inhibition is an important part of selective attention. This study explored components of inhibition-both intentional and reactive inhibition-during spoken-word production in PWA and in controls who were neurologically healthy (HC). Intentional inhibition is the ability to suppress a response to interference, and reactive inhibition is the delayed reactivation of a previously suppressed item. METHOD Nineteen PWA and 20 age- and education-matched HC participated in a Stroop spoken-word production task. This task allowed the examination of intentional and reactive inhibition by evoking and comparing interference, facilitation, and negative priming effects in different contexts. RESULTS Although both groups demonstrated intentional inhibition, PWA demonstrated significantly more interference effects. PWA demonstrated no significant facilitation effects. HC demonstrated significant reverse facilitation effects. Neither group showed significant evidence of reactive inhibition, though both groups showed similar individual variability. CONCLUSIONS These results underscore the challenge interference presents for PWA during spoken-word production, indicating diminished intentional inhibition. Although reactive inhibition was not different between PWA and HC, PWA showed difficulty integrating and adapting to contextual information during language tasks.