Edwin Maas

Motor programming in apraxia of speech

Apraxia of Speech (AOS) is an impairment of motor programming. However, the exact nature of this deficit remains unclear. The present study examined motor programming in AOS in the context of a recent two-stage model [Klapp, S. T. (1995). Motor response programming during simple and choice reaction time: The role of practice. Journal of Experimental Psychology: Human Perception and Performance, 21, 1015-1027; Klapp, S. T. (2003). Reaction time analysis of two types of motor preparation for speech articulation: Action as a sequence of chunks. Journal of Motor Behavior, 35, 135-150] that proposes a preprogramming stage (INT) and a process that assigns serial order to multiple programs in a sequence (SEQ). The main hypothesis was that AOS involves a process-specific deficit in the INT (preprogramming) stage of processing, rather than in the on-line serial ordering (SEQ) and initiation of movement. In addition, we tested the hypothesis that AOS involves a central (i.e., modality-general) motor programming deficit. We used a reaction time paradigm that provides two dependent measures: study time (the amount of time for participants to ready a motor response; INT), and reaction time (time to initiate movement; SEQ). Two experiments were conducted to examine INT and SEQ in AOS: Experiment 1 involved finger movements, Experiment 2 involved speech movements analogous to the finger movements. Results showed longer preprogramming time for patients with AOS but normal sequencing and initiation times, relative to controls. Together, the findings are consistent with the hypothesis of a process-specific, but central (modality-independent) deficit in AOS; alternative explanations are also discussed.

Ultrasound Visual Feedback Treatment and Practice Variability for Residual Speech Sound Errors

PURPOSE The goals were to (a) test the efficacy of a motor-learning-based treatment that includes ultrasound visual feedback for individuals with residual speech sound errors and (b) explore whether the addition of prosodic cueing facilitates speech sound learning. METHOD A multiple-baseline, single-subject design was used, replicated across 8 participants. For each participant, 1 sound context was treated with ultrasound plus prosodic cueing for 7 sessions, and another sound context was treated with ultrasound but without prosodic cueing for 7 sessions. Sessions included ultrasound visual feedback as well as non-ultrasound treatment. Word-level probes assessing untreated words were used to evaluate retention and generalization. RESULTS For most participants, increases in accuracy of target sound contexts at the word level were observed with the treatment program regardless of whether prosodic cueing was included. Generalization between onset singletons and clusters was observed, as was generalization to sentence-level accuracy. There was evidence of retention during posttreatment probes, including at a 2-month follow-up. CONCLUSION A motor-based treatment program that includes ultrasound visual feedback can facilitate learning of speech sounds in individuals with residual speech sound errors.

Treatment for acquired apraxia of speech: A systematic review of intervention research between 2004 and 2012

Objectives The aim was for the appointed committee of the Academy of Neurological Communication Disorders and Sciences to conduct a systematic review of published intervention studies of acquired apraxia of speech (AOS), updating the previous committees review article from 2006. Method A systematic search of 11 databases identified 215 articles, with 26 meeting inclusion criteria of (a) stating intention to measure effects of treatment on AOS and (b) data representing treatment effects for at least 1 individual stated to have AOS. Results All studies involved within-participant experimental designs, with sample sizes of 1 to 44 (median = 1). Confidence in diagnosis was rated high to reasonable in 18 of 26 studies. Most studies (24/26) reported on articulatory-kinematic approaches; 2 applied rhythm/rate control methods. Six studies had sufficient experimental control for Class III rating according to the Clinical Practice Guidelines Process Manual (American Academy of Neurology, 2011), with 15 others satisfying all criteria for Class III except use of independent or objective outcome measurement. Conclusions The most important global clinical conclusion from this review is that the weight of evidence supports a strong effect for both articulatory-kinematic and rate/rhythm approaches to AOS treatment. The quantity of work, experimental rigor, and reporting of diagnostic criteria continue to improve and strengthen confidence in the corpus of research.

Motor-Based Intervention Protocols in Treatment of Childhood Apraxia of Speech (CAS)

This paper reviews current trends in treatment for childhood apraxia of speech (CAS), with a particular emphasis on motor-based intervention protocols. The paper first briefly discusses how CAS fits into the typology of speech sound disorders, which is followed by a discussion of the potential relevance of principles derived from the motor learning literature for CAS treatment. Next, various motor-based treatment protocols are reviewed, along with their evidence base. The paper concludes with a summary and discussion of future research needs.

Feedforward and feedback control in apraxia of speech: effects of noise masking on vowel production

PURPOSE This study was designed to test two hypotheses about apraxia of speech (AOS) derived from the Directions Into Velocities of Articulators (DIVA) model (Guenther et al., 2006): the feedforward system deficit hypothesis and the feedback system deficit hypothesis. METHOD The authors used noise masking to minimize auditory feedback during speech. Six speakers with AOS and aphasia, 4 with aphasia without AOS, and 2 groups of speakers without impairment (younger and older adults) participated. Acoustic measures of vowel contrast, variability, and duration were analyzed. RESULTS Younger, but not older, speakers without impairment showed significantly reduced vowel contrast with noise masking. Relative to older controls, the AOS group showed longer vowel durations overall (regardless of masking condition) and a greater reduction in vowel contrast under masking conditions. There were no significant differences in variability. Three of the 6 speakers with AOS demonstrated the group pattern. Speakers with aphasia without AOS did not differ from controls in contrast, duration, or variability. CONCLUSION The greater reduction in vowel contrast with masking noise for the AOS group is consistent with the feedforward system deficit hypothesis but not with the feedback system deficit hypothesis; however, effects were small and not present in all individual speakers with AOS. Theoretical implications and alternative interpretations of these findings are discussed.

Limited acquisition and generalisation of rhotics with ultrasound visual feedback in childhood apraxia

ABSTRACT Ultrasound visual feedback of the tongue is one treatment option for individuals with persisting speech sound errors. This study evaluated children’s performance during acquisition and generalisation of American English rhotics using ultrasound feedback. Three children aged 10–13 with persisting speech sound errors associated with childhood apraxia of speech (CAS) were treated for 14 one-hour sessions. Two of the participants increased the accuracy of their rhotic production during practise trials within treatment sessions, but none demonstrated generalisation to untreated words. Lack of generalisation may be due to a failure to acquire the target with sufficient accuracy during treatment, or to co-existing linguistic weaknesses that are not addressed in a motor-based treatment. Results suggest a need to refine the intervention procedures for CAS and/or a need to identify appropriate candidates for intervention to optimise learning.

Motor-Based Treatment with and without Ultrasound Feedback for Residual Speech-Sound Errors.

BACKGROUND There is a need to develop effective interventions and to compare the efficacy of different interventions for children with residual speech-sound errors (RSSEs). Rhotics (the r-family of sounds) are frequently in error American English-speaking children with RSSEs and are commonly targeted in treatment. One treatment approach involves the use of ultrasound visual feedback of the tongue. AIMS Although prior studies have shown that children with RSSEs acquire rhotics and generalize to untrained words with ultrasound visual feedback treatment, predictions from schema-based motor learning theory suggest that visual feedback might impede generalization. Therefore, the primary aim was to compare the generalization of rhotics treated with and without ultrasound in children with RSSEs. METHODS & PROCEDURES Twelve children aged 10-16 years with RSSEs affecting rhotics participated in a multiple-baseline single-case design with two treatment phases. For each participant, rhotics in one syllable position were treated for 7 h-long sessions with ultrasound visual feedback and rhotics in a different syllable position were treated without ultrasound in a second treatment phase. The order of treatment conditions was counterbalanced across participants. A treatment framework incorporating the principles of motor learning through chaining procedures was implemented across both treatment phases; thus the primary distinction between conditions was the use of ultrasound visual feedback. OUTCOMES & RESULTS On average, both treatments resulted in an approximately 30% increase in accuracy of untreated words in seven sessions. However, variability in response suggested some children showed a preferential response to one treatment over another, some responded well to both interventions, and some responded minimally to both interventions. CONCLUSIONS & IMPLICATIONS Motor-based treatment with and without ultrasound visual feedback of the tongue may aid in speech-sound acquisition for children with RSSEs. Both approaches may be viable options for some children. Future research is necessary to determine which children are the best candidates for interventions with and without ultrasound visual feedback.

Phonological encoding in apraxia of speech and aphasia

Background: Apraxia of speech (AOS) is considered a speech motor planning/programming disorder. While it is possible that co-occurring phonological impairments exist, the speech motor planning/programming deficit often makes it difficult to assess the phonological encoding stage directly. Studies using online methods have suggested that activation of phonological information may be protracted in AOS. Aims: The present study was designed to investigate the integrity of the phonological encoding stage in AOS and aphasia. We tested two specific hypotheses, the Frame Hypothesis and the Segment Hypothesis. According to the Frame Hypothesis, speakers with AOS have an impairment in retrieving metrical frames (e.g., number of syllables); according to the Segment Hypothesis, speakers with AOS have an impairment in retrieving segments (e.g., consonants). Methods & Procedures: Four individuals with AOS and varying degrees of aphasia, two speakers with aphasia, and 13 age-matched control speakers completed an online priming task in which participants name pictures in sets that do or do not share number of syllables (e.g., balcony-coconut-signature vs. balcony-carrot-sock), the initial consonant (e.g., carpenter-castle-cage vs. carpenter-beaver-sun), or both (e.g., boomerang-butterfly-bicycle vs. boomerang-sausage-cat). Error rates and reaction times were measured. Outcomes & Results: Data for controls replicated previous literature. Reaction time data supported the Segment Hypothesis for speakers with AOS and for one speaker with aphasia without AOS, with no differences in pattern from controls for the other speaker with aphasia without AOS. Conclusions: These results suggest that speakers with AOS may also have difficulties at the phonological encoding stage. Theoretical and clinical implications of these findings are discussed.

Intensive Treatment with Ultrasound Visual Feedback for Speech Sound Errors in Childhood Apraxia

Ultrasound imaging is an adjunct to traditional speech therapy that has shown to be beneficial in the remediation of speech sound errors. Ultrasound biofeedback can be utilized during therapy to provide clients with additional knowledge about their tongue shapes when attempting to produce sounds that are erroneous. The additional feedback may assist children with childhood apraxia of speech (CAS) in stabilizing motor patterns, thereby facilitating more consistent and accurate productions of sounds and syllables. However, due to its specialized nature, ultrasound visual feedback is a technology that is not widely available to clients. Short-term intensive treatment programs are one option that can be utilized to expand access to ultrasound biofeedback. Schema-based motor learning theory suggests that short-term intensive treatment programs (massed practice) may assist children in acquiring more accurate motor patterns. In this case series, three participants ages 10–14 years diagnosed with CAS attended 16 h of speech therapy over a 2-week period to address residual speech sound errors. Two participants had distortions on rhotic sounds, while the third participant demonstrated lateralization of sibilant sounds. During therapy, cues were provided to assist participants in obtaining a tongue shape that facilitated a correct production of the erred sound. Additional practice without ultrasound was also included. Results suggested that all participants showed signs of acquisition of sounds in error. Generalization and retention results were mixed. One participant showed generalization and retention of sounds that were treated; one showed generalization but limited retention; and the third showed no evidence of generalization or retention. Individual characteristics that may facilitate generalization are discussed. Short-term intensive treatment programs using ultrasound biofeedback may result in the acquisition of more accurate motor patterns and improved articulation of sounds previously in error, with varying levels of generalization and retention.

Speech and nonspeech: What are we talking about?

Abstract Understanding of the behavioural, cognitive and neural underpinnings of speech production is of interest theoretically, and is important for understanding disorders of speech production and how to assess and treat such disorders in the clinic. This paper addresses two claims about the neuromotor control of speech production: (1) speech is subserved by a distinct, specialised motor control system and (2) speech is holistic and cannot be decomposed into smaller primitives. Both claims have gained traction in recent literature, and are central to a task-dependent model of speech motor control. The purpose of this paper is to stimulate thinking about speech production, its disorders and the clinical implications of these claims. The paper poses several conceptual and empirical challenges for these claims – including the critical importance of defining speech. The emerging conclusion is that a task-dependent model is called into question as its two central claims are founded on ill-defined and inconsistently applied concepts. The paper concludes with discussion of methodological and clinical implications, including the potential utility of diadochokinetic (DDK) tasks in assessment of motor speech disorders and the contraindication of nonspeech oral motor exercises to improve speech function.