Beyond Broca: neural architecture and evolution of a dual motor speech coordination system.

Classical neural architecture models of speech production propose a single system centred on Broca's area coordinating all the vocal articulators from lips to larynx. Modern evidence has challenged both the idea that Broca's area is involved in motor speech coordination and that there is only one coordination network. Drawing on a wide range of evidence, here we propose a dual speech coordination model in which laryngeal control of pitch-related aspects of prosody and song are coordinated by a hierarchically organized dorsolateral system while supralaryngeal articulation at the phonetic/syllabic level is coordinated by a more ventral system posterior to Broca's area. We argue further that these two speech production subsystems have distinguishable evolutionary histories and discuss the implications for models of language evolution.

Gaze-speech coordination during social interaction in Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) can affect social interaction and communication as well as motor and cognitive processes. Speech is affected in PD, as is the control of voluntary eye movements which are thought to play an important role in 'turn taking' in conversation. AIMS: This study aimed to measure eye movements during spoken conversation in PD to assess whether differences in patterns of eye gaze are linked to disrupted turn taking and impaired communication efficiency. METHODS & PROCEDURE: Eleven participants with mild PD and 14 controls completed a two-player guessing game. During each 3 min game turn, one of the players had to guess the names of as many objects as possible based only on the other player's description. Eye movements were recorded simultaneously in both participants using mobile eye trackers along with speech onset and offset times. OUTCOMES & RESULTS: When people with PD played the role of describer, the other player guessed fewer objects compared to when controls described objects. When guessing objects, people with PD performed just as well as controls. Analysis of eye fixations showed that people with PD made longer periods of fixation on the other player's face relative to controls and a lower number of such 'gaze on face' periods. CONCLUSIONS & IMPLICATIONS: A combination of oculomotor, cognitive and speech abnormalities may disrupt communication in PD. Better public awareness of oculomotor, speech and other deficits in the condition could improve social connectedness in people with Parkinson's. WHAT THIS PAPER ADDS: What is already known on this subject? Parkinson's disease is known to affect the control of voluntary eye movements. Direction of eye gaze is important in spoken conversation as a cue to turn-taking, but no studies have examined whether eye movements are different during communication in people with Parkinson's. What this paper adds to existing knowledge? People with Parkinson's showed longer periods of eye fixation during conversations compared to controls. Delays and overlaps between speech turns were also affected in patients. What are the clinical implications of this work? Better knowledge of the effect of the disease on eye gaze control amongst clinicians may help improve communication and social connectedness for patients in the future.

The encoding of speech modes in motor speech disorders: whispered versus normal speech in apraxia of speech and hypokinetic dysarthria.

Speakers with motor speech disorders (MSD) present challenges in speech production, one of them being the difficulty to adapt their speech to different modes. However, it is unclear whether different types of MSD are similarly affected when it comes to adapting their speech to various communication contexts. This study investigates the encoding of speech modes in individuals with AoS following focal brain damage and in individuals with hypokinetic dysarthria (HD) secondary to Parkinson's disease. Participants with mild-to-moderate MSD and their age-matched controls performed a delayed production task of pseudo-words in two speech modes: normal and whispered speech. While overall accuracy did not differ significantly across speech modes, participants with AoS exhibited longer response latencies for whispered speech, reflecting difficulties in the initiation of utterances requiring an unvoiced production. In contrast, participants with HD showed faster response latencies for whispered speech, indicating that this speech mode is easier to encode/control for this population. Acoustic durations followed these same trends, with participants with AoS showing greater lengthening for whispered speech as compared to controls and to participants with HD, while participants with HD exhibited milder lengthening. Contrary to the predictions of speech production models, suggesting that speech mode changes might be particularly difficult in dysarthria, the present results suggest that speech mode adaptation rather seems particularly costly for participants with AoS.

Dialect identification, intelligibility ratings, and acceptability ratings of dysarthric speech in two American English dialects.

The current study explored the intelligibility and acceptability ratings of dysarthric speakers with African American English (AAE) and General American English (GAE) dialects by listeners who identify as GAE or AAE speakers, as well as listener ability to identify dialect in dysarthric speech. Eighty-six listeners rated the intelligibility and acceptability of sentences extracted from a passage read by speakers with dysarthria. Samples were used from the Atlanta Motor Speech Disorders Corpus and ratings were collected via self-report. The listeners identified speaker dialect in a forced-choice format. Listeners self-reported their dialect and exposure to AAE. AAE dialect was accurately identified in 63.43% of the the opportunities; GAE dialect was accurately identified in 70.35% of the opportunities. Listeners identifying as AAE speakers rated GAE speech as more acceptable, whereas, listeners identifying as GAE speakers rated AAE speech as more acceptable. Neither group of listeners demonstrated a difference in intelligibility ratings. Exposure to AAE had no effect on intelligibility or acceptability ratings. Listeners can identify dialect (AAE and GAE) with a better than chance degree of accuracy. One's dialect may have an effect on intelligibility and acceptability ratings. Exposure to a dialect did not affect listener ratings of intelligibility or acceptability.

Treatment approaches to Motor Speech Disorders: A step towards Evidence Based Practice.

Motor Speech Disorders is an umbrella term for a set of separate dysfunctions of speech outcome associated with neurological disorders. Motor speech disorders (MSD) are classified as Speech Motor delay (SMD), Childhood dysarthria (CD), Childhood Apraxia of Speech (CAS), and Concurrent CD and CAS. The incidence and prevalence of MSD in population is uncertain. A research gap exists, making evidence-based practice questionable as regards intervention for MSD and is an area of research. Hence, current narrative review was conducted to review and highlight treatment of MSD since evidence-based treatment approach may benefit patient even years after a brain lesion. To achieve this objective literature search was conducted using search engines and data bases including google, google scholar, web of science & PubMed from 1998 to 2023 with keywords "motor speech disorder, dysarthria, apraxia, speech motor delay and combinations of these words with English language and no other limitations. Our search revealed 170 articles, news, publications of which 34 were used for review (Fig.1).

Time-course of phonetic (motor speech) encoding in utterance production.

Speaking involves the preparation of the linguistic content of an utterance and of the motor programs leading to articulation. The temporal dynamics of linguistic versus motor-speech (phonetic) encoding is highly debated: phonetic encoding has been associated either to the last quarter of an utterance preparation time (∼150ms before articulation), or to virtually the entire planning time, simultaneously with linguistic encoding. We (i) review the evidence on the time-course of motor-speech encoding based on EEG/MEG event-related (ERP) studies and (ii) strive to replicate the early effects of phonological-phonetic factors in referential word production by reanalysing a large EEG/ERP dataset. The review indicates that motor-speech encoding is engaged during at least the last 300ms preceding articulation (about half of a word planning lag). By contrast, the very early involvement of phonological-phonetic factors could be replicated only partially and is not as robust as in the second half of the utterance planning time-window.

Dose frequency randomized controlled trial for Dynamic Temporal and Tactile Cueing (DTTC) treatment for childhood apraxia of speech: protocol paper.

BACKGROUND: Childhood apraxia of speech (CAS) is a pediatric motor-based speech sound disorder that requires a specialized approach to intervention. The extant literature on the treatment of CAS commonly recommends intensive treatment using a motor-based approach, with some of the best evidence supporting the use of Dynamic Temporal and Tactile Cueing (DTTC). To date, a rigorous and systematic comparison of high and low dose frequency (i.e., frequency of therapy sessions) has not been undertaken for DTTC, resulting in a lack of evidence to guide decisions about the optimal treatment schedule for this intervention. The current study aims to fill this gap in knowledge by comparing treatment outcomes when dose frequency is varied. METHODS: A randomized controlled trial will be conducted to examine the efficacy of low versus high dose frequency on DTTC treatment outcomes in children with CAS. A target of 60 children, 2;6-7;11 years of age, will be recruited to participate in this study. Treatment will be provided in the community setting by speech-language pathologists who have completed specialized training administering DTTC in a research reliable manner. True randomization with concealed allocation will be used to assign children to either the low or high dose frequency group. Treatment will be administered in 1-h sessions either 4 times per week over a 6-week period (high dose) or 2 times per week over a 12-week period (low dose). To measure treatment gains, probe data will be collected before treatment, during treatment, and 1 day, 1 week, 4 weeks, and 12 weeks post-treatment. Probe data will consist of customized treated words and a standard set of untreated words to assess generalization of treatment gains. The primary outcome variable will be whole word accuracy, encompassing segmental, phonotactic, and suprasegmental accuracy. DISCUSSION: This will be the first randomized controlled trial to evaluate dose frequency for DTTC treatment in children with CAS. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT05675306, January 6, 2023.

Review of methods for conducting speech research with minimally verbal individuals with autism spectrum disorder.

The purpose of this paper was to review best-practice methods of collecting and analyzing speech production data from minimally verbal autistic speakers. Data on speech production data in minimally verbal individuals are valuable for a variety of purposes, including phenotyping, clinical assessment, and treatment monitoring. Both perceptual ("by ear") and acoustic analyses of speech can reveal subtle improvements as a result of therapy that may not be apparent when correct/incorrect judgments are used. Key considerations for collecting and analyzing speech production data from this population are reviewed. The definition of "minimally verbal" that is chosen will vary depending on the specific hypotheses investigated, as will the stimuli to be collected and the task(s) used to elicit them. Perceptual judgments are ecologically valid but subject to known sources of bias; therefore, training and reliability procedures for perceptual analyses are addressed, including guidelines on how to select vocalizations for inclusion or exclusion. Factors to consider when recording and acoustically analyzing speech are also briefly discussed. In summary, the tasks, stimuli, training methods, analysis type(s), and level of detail that yield the most reliable data to answer the question should be selected. It is possible to obtain rich high-quality data even from speakers with very little speech output. This information is useful not only for research but also for clinical decision-making and progress monitoring.

Perceptual measurement of articulatory goodness in young children: Relationships with age, speech sound acquisition, and intelligibility.

Speech language pathologists regularly use perceptual methods in clinical practice to assess children's speech. In this study, we examined relationships between measures of speech intelligibility, clinical articulation test results, age, and perceptual ratings of articulatory goodness for children. We also examined the extent to which established measures of intelligibility and clinical articulation test results predicted articulatory goodness ratings, and whether goodness ratings were influenced by intelligibility. A sample of 164 (30-47 months) typically developing children provided speech samples and completed a standardised articulation test. Single word intelligibility scores and ratings of articulatory goodness were gathered from 328 naïve listeners; scores on a standardised articulation test were obtained from each child. Bivariate Pearson correlation, linear regression, and linear mixed effects modelling were used for analysis. Results showed that articulatory goodness ratings had the highest correlation with intelligibility, followed by age, followed by articulation score. Age and clinical articulation scores were both significant predictors of goodness ratings, but articulation scores made only a small contribution to prediction. Articulatory goodness ratings were substantially lower for unintelligible words compared to intelligible words, but articulatory goodness scores increased with age at the same rate for unintelligible and intelligible words. Perceptual ratings of articulatory goodness are sensitive to developmental changes in speech production (regardless of intelligibility) and yield a different kind of information than clinical articulation scores from standardised measures.

Neuropsychological Profiles of Patients with Progressive Apraxia of Speech and Aphasia.

OBJECTIVE: To characterize and compare the neuropsychological profiles of patients with primary progressive apraxia of speech (PPAOS) and apraxia of speech with progressive agrammatic aphasia (AOS-PAA). METHOD: Thirty-nine patients with PPAOS and 49 patients with AOS-PAA underwent formal neurological, speech, language, and neuropsychological evaluations. Cognitive domains assessed included immediate and delayed episodic memory (Wechsler Memory Scale-Third edition; Logical Memory; Visual Reproduction; Rey Auditory Verbal Learning Test), processing speed (Trail Making Test A), executive functioning (Trail Making Test B; Delis-Kaplan Executive Functioning Scale - Sorting), and visuospatial ability (Rey-Osterrieth Complex Figure copy). RESULTS: The PPAOS patients were cognitively average or higher in the domains of immediate and delayed episodic memory, processing speed, executive functioning, and visuospatial ability. Patients with AOS-PAA performed more poorly on tests of immediate and delayed episodic memory and executive functioning compared to those with PPAOS. For every 1 unit increase in aphasia severity (e.g. mild to moderate), performance declined by 1/3 to 1/2 a standard deviation depending on cognitive domain. The degree of decline was stronger within the more verbally mediated domains, but was also notable in less verbally mediated domains. CONCLUSION: The study provides neuropsychological evidence further supporting the distinction of PPAOS from primary progressive aphasia and should be used to inform future diagnostic criteria. More immediately, it informs prognostication and treatment planning.

PROMPT to improve speech motor abilities in children with cerebral palsy: a wait-list control group trial protocol.

BACKGROUND: Children with cerebral palsy (CP) often have communication impairments, including speech altered intelligibility. Multiple levels of disrupted speech have been reported in CP, which negatively impact on participation and quality of life, with increase of care needs. Augmentative Alternative Communication (AAC) is an option, with debated benefits and limitations, in particular for its functional use. This is supported by a substantial lack of defined evidences in favor of direct speech articulation intervention in CP. Motor learning-based interventions are effective in CP and are the basis of speech motor interventions such as PROMPT (Prompts for Restructuring Oral Muscular Phonetic Targets). The PROMPT speech motor treatment provides tactile-kinesthetic inputs to facilitate articulatory movements by dynamic modelling, resulting in more efficient motor patterns that can be integrated into speech and communication. In CP, exploratory evidences support the feasibility and preliminarily advantages on intelligibility of motor speech treatments, such as PROMPT, with increased speech motor control, also documented by kinematic analyses. METHODS: A randomized waitlist-control trial will be conducted in children aged between 3- and 10-years having CP and dysarthria (estimated sample size = 60 children). Children will be allocated in the immediate intervention or in the waitlist control group. The intervention consists of an intensive 3 weeks period of twice-a-day administration of PROMPT. Standard care will be administered in the control (waitlist) group. After repeated baseline assessments (T0), the PROMPT treated group will undergo the experimental 3-week intervention period, with T1 assessment at the end. A further T2 assessment will be provided at medium term (3 months after the end of the intervention) for evaluating the stability of intervention. Primary and secondary speech clinical and kinematics outcome measures will be collected at T0, T1 and T2. DISCUSSION: This paper describes the study protocol consisting of a RCT with two main objectives: (1) to evaluate the or short-term benefits of an intensive speech motor intervention on speech and intelligibility in children with CP and the stability of the intervention at medium term; (2) to describe the kinematic correlates of speech motor control modifications. TRIAL REGISTRATION: Trial registration date 06/12/2019; ClinicalTrials.gov Identifier: NCT04189159 .

Cross-Modal Somatosensory Repetition Priming and Speech Processing.

BACKGROUND: Motor speech treatment approaches have been applied in both adults with aphasia and apraxia of speech and children with speech-sound disorders. Identifying links between motor speech intervention techniques and the modes of action (MoA) targeted would improve our understanding of how and why motor speech interventions achieve their effects, along with identifying its effective components. The current study focuses on identifying potential MoAs for a specific motor speech intervention technique. OBJECTIVES: We aim to demonstrate that somatosensory inputs can influence lexical processing, thus providing further evidence that linguistic information stored in the brain and accessed as part of speech perception processes encodes information related to speech production. METHODS: In a cross-modal repetition priming paradigm, we examined whether the processing of external somatosensory priming cues was modulated by both word-level (lexical frequency, low- or high-frequency) and speech sound articulatory features. The study participants were divided into two groups. The first group consisted of twenty-three native English speakers who received somatosensory priming stimulation to their oro-facial structures (either to labial corners or under the jaw). The second group consisted of ten native English speakers who participated in a control study where somatosensory priming stimulation was applied to their right or left forehead as a control condition. RESULTS: The results showed significant somatosensory priming effects for the low-frequency words, where the congruent somatosensory condition yielded significantly shorter reaction times and numerically higher phoneme accuracy scores when compared to the incongruent somatosensory condition. Data from the control study did not reveal any systematic priming effects from forehead stimulation (non-speech related site), other than a general (and expected) tendency for longer reaction times with low-frequency words. CONCLUSIONS: These findings provide further support for the notion that speech production information is represented in the mental lexicon and can be accessed through exogenous Speech-Language Pathologist driven somatosensory inputs related to place of articulation.

Sports Related Concussion Impacts Speech Rate and Muscle Physiology.

OBJECTIVE: Establish objective and subjective speech rate and muscle function differences between athletes with and without sports related concussion (SRC) histories and provide potential motor speech evaluation in SRC. METHODS: Over 1,110 speech samples were obtained from 30, 19-22 year-old athletes who had sustained an SRC within the past 2 years and 30 pair-wise matched control athletes with no history of SRC. Speech rate was measured via average time per syllable, average unvoiced time per syllable, and expert perceptual judgment. Speech muscle function was measured via surface electromyography over the obicularis oris, masseter, and segmental triangle. Group differences were assessed using MANOVA, bootstrapping and predictive ROC analyses. RESULTS: Athletes with SRC had slower speech rates during DDK tasks than controls as evidenced by longer average time per syllable longer average unvoiced time per syllable and expert judgment of slowed rate. Rate measures were predictive of concussion history. Further, athletes with SRC required more speech muscle activation than controls to complete DDK tasks. CONCLUSION: Clear evidence of slowed speech and increased muscle activation during the completion of DDK tasks in athletes with SRC histories relative to controls. Future work should examine speech rate in acute concussion.

Progressive apraxia of speech in Quebec French speakers: A case series.

BACKGROUND: The term progressive apraxia of speech (PAOS) is used to describe speakers presenting with isolated or dominant apraxia of speech in the context of a neurodegenerative syndrome, including primary progressive apraxia of speech (PPAOS) and dominant progressive apraxia of speech (DAOS), respectively. Its motor speech profile has been increasingly explored in the last decade, but description remains vague and very English oriented, although the effect of speakers' language on motor speech phenotypes is increasingly recognized. Although some studies suggest that speakers presenting with isolated PAOS (PPAOS) versus dominant PAOS with concomitant aphasia (DAOS) should be differentiated, distinct characteristics of the two presentations are unclear. Furthermore, a careful description of their clinical presentation in languages other than English is required. AIMS: To describe the motor speech characteristics of Quebec French-speaking participants with prominent PAOS and to explore the communication profile of those presenting more specifically with isolated PAOS (PPAOS), and with dominant PAOS and concomitant aphasia (DAOS). METHODS & PROCEDURES: A thorough effort to recruit all speakers presenting with PAOS in the larger population areas of the province of Quebec was conducted over a 3-year span. A total of nine participants with PAOS (pwPAOS; PPAOS = 5, DAOS = 4) underwent a comprehensive language and motor speech assessment, and a cognitive screening. Their performance was compared with 30 matched healthy controls. OUTCOMES & RESULTS: As a group, pwPAOS differed from healthy speakers on all acoustic and perceptual measures. The PPAOS and PAOS subgroups were similar on several measures, but participants from the PPAOS subgroup tended to perform better on articulatory measures and maximum speech rate tasks. CONCLUSIONS & IMPLICATIONS: This study provides an in-depth analysis of motor speech characteristics of PAOS in Quebec French speakers and adds further evidence for the differentiation of PPAOS and DAOS. Combining simple perceptual and acoustic analyses represent a promising approach to distinguish the two variants and identify treatment targets. What this paper adds What is already known on this subject Progressive apraxia of speech (PAOS) is a neurodegenerative syndrome characterized by progressive and initially isolated or dominant apraxia of speech (primary progressive apraxia of speech [PPAOS] and dominant progressive apraxia of speech [DAOS], respectively). Studies mostly report articulatory and prosodic deficits in PAOS, but concomitant deficits such as dysarthria and executive dysfunction are also reported. The description of motor speech skills in PAOS remains vague and English-oriented. Studies suggest that speakers presenting with isolated PAOS vs dominant PAOS with concomitant aphasia should be differentiated, but distinct characteristics of the two presentations are unclear. What this study adds to existing knowledge To the best of the authors' knowledge, this study is the first to report transversal data of Quebec-French participants with PPAOS and DAOS. Moreover, this study is a first step towards identifying potential characteristics that could facilitate the diagnosis of PPAOS and DAOS in Quebec French. It makes a significant contribution to our understanding of progressive apraxia of speech in different cultural languages. What are the potential or actual clinical implications of this work? This study also initiates the search for sensitive tasks for the diagnosis of those speakers (which is an important process), in addition to identifying the core characteristics of PAOS, DAOS, and PPAOS in the development of an assessment battery for this population.

Effects of Practice Variability on Second-Language Speech Production Training.

BACKGROUND: Mastering the phonetics of a second language (L2) involves a component of speech-motor skill, and it has been suggested that L2 learners aiming to achieve a more native-like pronunciation could benefit from practice structured in accordance with the principles of motor learning. PARTICIPANTS AND METHODS: This study investigated the influence one such principle, high versus low variability in practice, has on speech-motor learning for Korean adults seeking to acquire native-like production of English rhotics. Practice incorporated a commercially available intraoral placement device ("R Buddy," Speech Buddies Inc.). In a single-subject across-behaviors design, 8 participants were pseudorandomly assigned to practice rhotic targets in a low-variability (single word) or high-variability (multiple words) practice condition. RESULTS: The hypothesized advantage for high-variability over low-variability practice was observed in the short-term time frame. However, long-term learning was limited in nature for both conditions. CONCLUSION: These results suggest that future research should incorporate high-variability practice while identifying additional manipulations to maximize the magnitude of long-term generalization learning.

Sensitivity and specificity of an acoustic- and perceptual-based tool for assessing motor speech disorders in French: the MonPaGe-screening protocol.

To respond to the need of objective screening tools for motor speech disorders (MSD), we present the screening version of a speech assessment protocol (MonPaGe-2.0.s), which is based on semi-automated acoustic and perceptual measures on several speech dimensions in French. We validate the screening tool by testing its sensitivity and specificity and comparing its outcome with external standard assessment tools. The data from 80 patients diagnosed with different types of mild to moderate MSD and 62 healthy test controls were assessed against the normative data obtained on 404 neurotypical speakers, with Deviance Scores computed on seven speech dimensions (voice, speech rate, articulation, prosody, pneumophonatory control, diadochokinetic rate, intelligibility) based on acoustic and perceptual measures. A cut-off of the MonPaGe total deviance score (TotDevS) >2 allowed MSD to be diagnosed with specificity of 95% and an overall sensitivity of 83.8% on all patients pulled, reaching 91% when very mildly impaired patients were excluded. A strong correlation was found between the MonPaGe TotDevS and an external composite perceptual score of MSD provided by six experts. The MonPaGe screening protocol has proven its sensitivity and specificity for diagnosing presence and severity of MSD. Further implementations are needed to complement the characterization of impaired dimensions in order to distinguish subtypes of MSD.

Comparing global motor characteristics in children and adults with childhood apraxia of speech to a cerebellar stroke patient: evidence for the cerebellar hypothesis in a developmental motor speech disorder.

Individuals with childhood apraxia of speech (CAS) have motor deficits in systems beyond speech and also global deficits in sequential processing, consistent with cerebellar dysfunction. We investigated the cerebellar hypothesis of CAS in 18 children and adolescents with CAS, 11 typical controls, an adult with a probable CAS history, and an adult with a history of a cerebellar stroke. Compared to the controls, children and adolescents with CAS had the greatest difficulty with rapid syllable repetition when alternating between two different syllables types, less difficulty when switching among three different syllables, and no difficulty when repeating the same syllable. They also showed difficulty with alternating but not repetitive key tapping. Motor speeds during the syllable repetition and key tapping tasks where correlated, consistent with a central motor delimiter that governs both systems. Participants with CAS obtained low scores in a test of fine motor ability, where the tasks required rapid integration of complex hand movement sequences. The adult with the probable CAS history obtained motor performance scores that generally resembled those in the children and adolescents with CAS, consistent with motor deficits that persist into adulthood. The participant with the cerebellar stroke history showed deficits in tests of fine and gross motor ability as well as balance. His repetitive and alternating key tapping was slow in the ipsilateral hand relative to the stroke lesion. The shared deficits in sequential motor functions among all participants with CAS and the cerebellar stroke patient are consistent with persisting cerebellar dysfunctions in CAS.

Attention/memory complaint is correlated with motor speech disorder in Parkinson's disease.

BACKGROUND: The mechanisms underlying the online modulation of motor speech in Parkinson's disease (PD) have not been determined. Moreover, medical and rehabilitation interventions for PD-associated motor speech disorder (MSD) have a poor long-term prognosis. METHODS: To compare risk factors in PD patients with MSD to those without MSD (non-MSD) and determine predictive independent risk factors correlated with the MSD phenotype, we enrolled 314 PD patients, including 250 with and 64 without MSD. We compared demographic, characteristic data, as well as PD-associated evaluations between the MSD group and non-MSD group. RESULTS: Univariate analysis showed that demographic characteristics, including occupation, educational level, monthly income and speaking background; clinical characteristics, including lesions in the frontal and temporal lobes, and concurrent dysphagia; and PD-associated evaluations, including the activity of daily living (ADL) score, non-motor symptoms scale (NMSS) domain 4 score (perceptual problem), and NMSS domain 5 score (attention/memory) were all significantly different between the MSD and non-MSD group (all P < 0.05). Multivariate logistic regression analysis showed that educational level, frontal lesions, and NMSS domain 5 score (attention/memory) were independent risk factors for PD-associated MSD (all P < 0.005). CONCLUSIONS: We determined an association between MSD phenotype and cognitive impairment, reflected by low-level education and related clinical profiles. Moreover, attention and memory dysfunction may play key roles in the progression of MSD in PD patients. Further studies are required to detail the mechanism underlying abnormal speech motor modulation in PD patients. Early cognitive intervention may enhance rehabilitation management and motor speech function in patients with PD-associated MSD.

Sub-classification of apraxia of speech in patients with cerebrovascular and neurodegenerative diseases.

Some studies have hypothesized that primary progressive apraxia of speech (ppAOS) consists of heterogeneous symptoms that can be sub-classified; however, no study has classified stroke-induced AOS (sAOS) and ppAOS according to common criteria. The purpose of this study was to elucidate the symptoms and relevant brain regions associated with sAOS and ppAOS for sub-classification. Participants included 8 patients with sAOS following lesions in the left precentral gyrus and/or underlying white matter, and 3 patients with ppAOS. All patients with sAOS could be classified into three subtypes: type I, with prominent distorted articulation; type II, with prominent prosodic abnormalities or type III, with similarly distorted articulation and prosodic abnormalities. This sub-classification was consistent with the subtypes of ppAOS proposed in previous reports. All patients with ppAOS were classified as type III, and exhibited three characteristics distinguishable from those of sAOS. First, they showed prominent lengthened syllables compared with the segmentation of syllables. Second, they could not always complete the production of multi-syllabic single words in one breath. Finally, they showed dysfunctional lesions in the bilateral supplementary motor area. We conclude that sAOS and ppAOS can be sub-classified and are universal symptoms that are common between the English and Japanese populations.

Effects of Deep Brain Stimulation of the Subthalamic Nucleus Settings on Voice Quality, Intensity, and Prosody in Parkinson's Disease: Preliminary Evidence for Speech Optimization.

OBJECTIVE: To systematically evaluate how different deep brain stimulation of the subthalamic nucleus (STN-DBS) amplitude, frequency, and pulse-width electrical parameter settings impact speech intensity, voice quality, and prosody of speech in Parkinson's disease (PD). METHODS: Ten individuals with PD receiving bilateral STN-DBS treatments were seen for three baseline and five treatment visits. The five treatment visits involved an examination of the standard clinical settings as well as manipulation of different combinations of frequency (low, mid, and high), pulse width (low, mid, and high), and voltage (low, mid, and high) of stimulation. Measures of speech intensity, jitter, shimmer, harmonics-noise ratio, semitone standard deviation, and listener ratings of voice quality and prosody were obtained for each STN-DBS manipulation. RESULTS: The combinations of lower frequency, lower pulse width, and higher voltage settings were associated with improved speech outcomes compared to the current standard clinical settings. In addition, decreased total electrical energy delivered to the STN appears to be associated with speech improvements. CONCLUSIONS: This study provides preliminary evidence that STN-DBS may be optimized for Parkinson-related problems with voice quality, speech intensity, and prosody of speech.