Changes in movement transitions across a practice period in childhood apraxia of speech

Maria I Grigos, Julie Case, Maria I Grigos, Julie Case

Abstract

This study examined changes in speech motor control across a movement transition between sounds within a motor learning task in children with apraxia of speech (CAS) and typical development (TD). It was investigated whether oral articulator movement was refined with practice and whether practice gains generalized to words not included in the practice session. A total of 16 children (ages 5-6) with CAS (n = 8) and TD (n = 8) participated in this study. Novel and real word tokens were produced at three time points. Kinematic data was collected using facial motion tracking at each time point. Children completed a practice session following baseline data collection session that integrated motor learning principles. Three tokens were included in the practice session and the remaining stimuli assessed carryover of practice gains. Kinematic data was then collected immediately following practice and 3 days later. Kinematic analyses were conducted on the movement gesture for the first syllable of each word. Narrow transcription analyses examined speech production accuracy. Children in the CAS group displayed increased consonant and vowel accuracy only for the practised tokens. Adjustments to spatial control and movement variability were observed in the CAS group, though only for practised words. Children in the TD group altered spatial and temporal domains of movement and variability across both practised and non-practised tokens. Interestingly, the CAS group displayed a pattern of increased displacement along with decreased variability, which was not observed in the TD group. The degree to which these findings reflect facilitative or maladaptive changes are discussed. Results are also interpreted in relation to vowel properties, novel/real word status and variable practice of novel and real words.

Keywords: Movement transitions; childhood apraxia of speech; speech motor learning.

Conflict of interest statement

Declaration of Interest

The authors report no conflicts of interest.

Figures

Figure 1.
Figure 1.
Twelve reflective markers placed on the lips, jaw, nose and forehead.
Figure 2.
Figure 2.
Kinematic traces of jaw displacement and lip aperture corresponding to the utterance “bubblegum.” Displacement measures were based on maximum displacement points. Displacement into oral opening for the first vowel was measured from the point of maximum closing displacement for the initial consonant (Point A) to the point of maximum opening displacement for the following vowel (Point B). The lip aperture trajectory reflects the distance between the upper and lower lips. Lip aperture into oral opening was measured from lip closing (Point C) to lip opening (Point D).
Figure 3.
Figure 3.
The mean and standard error jaw displacement and jaw displacement variability as measured by the coefficient of variation (COV) for the practiced novel words (PR_RW), practiced real word (PR_RW), and non-practiced words (NPR) at baseline (T1), immediately following practice (T2), and following a three-day interval (T3) in children with TD (a, b) and CAS (c, d).

Source: PubMed

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