Abnormal Speech Motor Control in Individuals with 16p11.2 Deletions.

Speech and motor deficits are highly prevalent (>70%) in individuals with the 600 kb BP4-BP5 16p11.2 deletion; however, the mechanisms that drive these deficits are unclear, limiting our ability to target interventions and advance treatment. This study examined fundamental aspects of speech motor control in participants with the 16p11.2 deletion. To assess capacity for control of voice, we examined how accurately and quickly subjects changed the pitch of their voice within a trial to correct for a transient perturbation of the pitch of their auditory feedback. When compared to controls, 16p11.2 deletion carriers show an over-exaggerated pitch compensation response to unpredictable mid-vocalization pitch perturbations. We also examined sensorimotor adaptation of speech by assessing how subjects learned to adapt their sustained productions of formants (speech spectral peak frequencies important for vowel identity), in response to consistent changes in their auditory feedback during vowel production. Deletion carriers show reduced sensorimotor adaptation to sustained vowel identity changes in auditory feedback. These results together suggest that 16p11.2 deletion carriers have fundamental impairments in the basic mechanisms of speech motor control and these impairments may partially explain the deficits in speech and language in these individuals

Effects of Hippotherapy on Coordination of Speech in a Person with Traumatic Brain Injury

Hippotherapy occurs when physical therapists, occupational therapists, and speechlanguage pathologists use the movement of a horse as a treatment strategy. Previous research has documented improvements in gross motor function such as walking, reaching, standing, balance, and trunk control following treatment that incorporates hippotherapy. However, no study to date has investigated the effect of hippotherapy on fine motor control functions such as speech. The purpose of the study was to complete a pilot investigation of the effects of hippotherapy on speech motor control in one person with traumatic brain injury. The treatment records of a 24 yearold woman with TBI who received speech therapy using hippotherapy were reviewed and the speech motor control data from ten sessions was extrapolated. Results indicated immediate improvement in speech motor control with continued improvement through session ten

Connected speech processes as multitier/multiarticulator prosodic modulations

A model is proposed that interprets a variety of connected speech processes as resulting from prosodic modulations at different tiers of functional speech motor control along the hypo-hyper dimension [10]. The general background of the model is given by the trichotomy of A-, B- and C-prosodic phenomena [15] that together constitute the acoustic makeup of any speech utterance (with regard to their respective time domains at the uttarance/phrase level, the syllabic level and the segmental level)

Speech Production as State Feedback Control

Spoken language exists because of a remarkable neural process. Inside a speaker's brain, an intended message gives rise to neural signals activating the muscles of the vocal tract. The process is remarkable because these muscles are activated in just the right way that the vocal tract produces sounds a listener understands as the intended message. What is the best approach to understanding the neural substrate of this crucial motor control process? One of the key recent modeling developments in neuroscience has been the use of state feedback control (SFC) theory to explain the role of the CNS in motor control. SFC postulates that the CNS controls motor output by (1) estimating the current dynamic state of the thing (e.g., arm) being controlled, and (2) generating controls based on this estimated state. SFC has successfully predicted a great range of non-speech motor phenomena, but as yet has not received attention in the speech motor control community. Here, we review some of the key characteristics of speech motor control and what they say about the role of the CNS in the process. We then discuss prior efforts to model the role of CNS in speech motor control, and argue that these models have inherent limitations – limitations that are overcome by an SFC model of speech motor control which we describe. We conclude by discussing a plausible neural substrate of our model

Stone tools and the linguistic capabilities of earlier hominids

The evolution of human manipulative abilities may be clearly linked to the evolution of speech motor control Both creativity and complexity in vocal and manipulative gestures may be closely linked to a single dimension of brain evolution — the evolution of absolute brain size. Inferring the linguistic capabilities of earlier hominids from their lithic artefacts, however, required us to take account of domain-specific constraints on manipulative skill In this article we report on a pilot flint-knapping experiment designed to identify such constraints ‘in action’

Speech planning as an index of speech motor control maturity

International audienceThis paper investigates speech motor control maturity in 4-year-old Canadian French children. Acoustic and ultrasound data recorded from four children, and for comparison, from four adults, are presented and analyzed. Maturity of speech motor control is assessed by measuring two characteristics: token-to-token variability of isolated vowels, as a measure of motor control accuracy, and extra-syllabic anticipatory coarticulation within V1-C-V2 sequences. In line with theories of optimal motor control, anticipatory coarticulation is assumed to be based on the use of internal models of the speech apparatus and its efficiency is considered to reflect the maturity of these representations. In agreement with former studies, token-to-token variability is larger in children than in adults. An anticipation of V2 in V1 was found in all adults but in none of the children studied so far. These results indicate that children's speech motor control is immature from two perspectives: insufficiently accurate motor control patterns for vowel production, and inability to anticipate forthcoming gestures. Both aspects are discussed and interpreted in the context of the immaturity of the internal representations of the speech motor apparatus in 4-year-old children

A 3D biomechanical vocal tract model to study speech production control: How to take into account the gravity?

This paper presents a modeling study of the way speech motor control can deal with gravity to achieve steady-state tongue positions. It is based on simulations carried out with the 3D biomechanical tongue model developed at ICP, which is now controlled with the Lambda model (Equilibrium-Point Hypothesis). The influence of short-delay orosensory feedback on posture stability is assessed by testing different muscle force/muscle length relationships (Invariant Characteristics). Muscle activation patterns necessary to maintain the tongue in a schwa position are proposed, and the relations of head position, tongue shape and muscle activations are analyzed

Effects of physiological arousal on speech motor control and speech motor practice in preschool-age children who do and do not stutter

Purpose: We examined the effects of physiological arousal on speech motor control and speech motor practice effects in preschool-age children who do (CWS) and do not stutter (CWNS). Method: Participants included 18 CWS (mean age 4 years, 5 months) and 18 age- and gender-matched CWNS. The participants repeated a phrase “buy bobby a puppy” interspersed with viewing pictures from the International Affective Picture System under two experimental conditions speaking after viewing pictures with (1) negative, and (2) neutral valence. Participants’ lip movements were tracked using Optotrak system. The spatio-temporal index (STI; Smith, Goffman, Zelaznik, Ying & McGillem, 1995) and mean utterance duration were calculated to examine speech motor control and speech motor practice effects. Skin conductance level was measured during the experimental conditions to assess participants’ physiological level of arousal. Results: Preschool-age CWS demonstrated greater speech movement variability across all conditions and trials than CWNS. Further, the younger participants produced more variable articulatory movements than the older participants. Participants’ speech movement variability did not significantly differ between the negative and neutral experimental conditions and the level of physiological arousal did not have a significant effect on it. There was a non-significant trend of decrease in speech movement variability across the repeated trials in both groups. Last, CWS and CWNS did not differ in their mean utterance duration, suggesting that their articulation rate was similar across all conditions and trials. Conclusions: Our findings indicate that, compared to preschool-age CWNS, CWS demonstrate less mature speech motor control. However, present findings do not support the hypothesis that CWS benefit less from motor practice relative to CWNS. Given that our conditions elicited similar levels of arousal in the participants, future research is needed to examine whether physiological arousal disrupts speech motor control in preschool-age children potentially contributing to disruptions of speech fluency and the development of stuttering