Dynamic respiratory muscle function in late-onset Pompe disease

Maximal inspiratory pressure (PIMAX) reflects inspiratory weakness in late-onset Pompe disease (LOPD). However, static pressure tests may not reveal specific respiratory muscle adaptations to disruptions in breathing. We hypothesized that dynamic respiratory muscle functional tests reflect distinct ventilatory compensations in LOPD. We evaluated LOPD (n = 7) and healthy controls (CON, n = 7) during pulmonary function tests, inspiratory endurance testing, dynamic kinematic MRI of the thorax, and ventilatory adjustments to single-breath inspiratory loads (inspiratory load compensation, ILC). We observed significantly lower static and dynamic respiratory function in LOPD. PIMAX, spirometry, endurance time, and maximal diaphragm descent were significantly correlated. During single-breath inspiratory loads, inspiratory time and airflow acceleration increased to preserve volume, and in LOPD, the response magnitudes correlated to maximal chest wall kinematics. The results indicate that changes in diaphragmatic motor function and strength among LOPD subjects could be detected through dynamic respiratory testing. We concluded that neuromuscular function significantly influenced breathing endurance, timing and loading compensations.

Energy flows in gesture-speech physics: Exploratory findings and pre-registration of confirmatory analysis

A well-known phenomenon of multimodal language is the synchronous coupling of prosodic contours in speech with salient kinematic changes in co-speech hand-gesture motions. Invariably, such coupling has been rendered by psychologists to require a dedicated neural-cognitive mechanism preplanning speech and gesture trajectories. Recently, in a continuous vocalization task, it was found that acoustic peaks unintentionally appear in vocalizations when gesture motions reach peaks in physical impetus, suggesting a biomechanical basis for gesture-speech synchrony (Pouw, Harrison, & Dixon, 2019). However, from this rudimentary study it is still difficult to draw strong conclusions about gesture-speech dynamics in (more) complex speech and the precise biomechanical nature of these effects. Here we assess how the timing of physical impetus of a gesture relates to its effect on acoustic parameters of mono-syllabic consonant-vowel (CV) vocalization(/pa/). Furthermore, we assess how chest-wall kinematics is affected by gesturing, and whether this modulates the effect of gestures on acoustics. In the current exploratory analysis, we analyze a subset (N = 4) of an already collected dataset (N = 36), which serves as the basis for a pre-registration of the confirmatory analyses yet to be completed. Here we provide exploratory evidence that gestures affect acoustics (amplitude envelope and F0) as well as chest-wall kinematics during mono-syllabic vocalizations. These effects are more extreme when a gesture’s peak impetus occurs closer to the center of the vowel vocalization event. If the current findings can be replicated in confirmatory fashion, there is a more compelling case to be made that gesture-speech physics is important facet of multimodal synchrony.

Chest Wall Kinematics Using Triangular Cosserat Point Elements in Healthy and Neuromuscular Subjects

Optoelectronic plethysmography (OEP) is a noninvasive method for assessing lung volume variations and the contributions of different anatomical compartments of the chest wall (CW) through measurements of the motion of markers attached to the CW surface. The present study proposes a new method for analyzing the local CW kinematics from OEP measurements based on the kinematics of triangular Cosserat point elements (TCPEs). 52 reflective markers were placed on the anterior CW to create a mesh of 78 triangles according to an anatomical model. Each triangle was characterized by a TCPE and its kinematics was described using four time-variant scalar TCPE parameters. The total CW volume ( VTCW) and the contributions of its six compartments were also estimated, using the same markers. The method was evaluated using measurements of ten healthy subjects, nine patients with Pompe disease, and ten patients with Duchenne muscular dystrophy (DMD), during spontaneous breathing (SB) and vital capacity maneuvers (VC) in the supine position. TCPE parameters and compartmental volumes were compared with VTCW by computing the phase angles θ (for SB) and the correlation r (for VC) between them. Analysis of θ and r of the outward translation parameter PT of each TCPE revealed that for healthy subjects it provided similar results to those obtained by compartmental volumes, whereas for the neuromuscular patients the TCPE method was capable of detecting local asynchronous and paradoxical movements also in cases where they were undistinguished by volumes. Therefore, the TCPE approach provides additional information to OEP that may enhance its clinical evaluation capabilities.

Modulation of chest wall intermuscular coherence: effects of lung volume excursion and transcranial direct current stimulation

Chest wall muscle recruitment varies as a function of the breathing task performed. However, the cortical control of the chest wall muscles during different breathing tasks is not known. We studied chest wall intermuscular coherence during various task-related lung volume excursions in 10 healthy adults (34 ± 15 yr; 2 men, 8 women) and determined if transcranial direct current stimulation (tDCS) could modulate chest wall intermuscular coherence during these tasks. Simultaneous assessment of regional intercostal and oblique electromyographic activity was measured while participants performed standardized tidal breathing, speech, maximum phonation, and vital capacity tasks. Lung volume and chest wall kinematics were determined using variable inductance plethysmography. We found that chest wall area of intermuscular coherence was greater during tidal and speech breathing compared with phonation and vital capacity (all P < 0.05) and between tidal breathing compared with speech breathing ( P < 0.05). Anodal tDCS increased chest wall area of intermuscular coherence from 0.04 ± 0.09 prestimulation to 0.18 ± 0.19 poststimulation for vital capacity ( P < 0.05). Sham tDCS and cathodal tDCS had no effect on coherence during lung volume excursions. Chest wall kinematics were not affected by tDCS. Our findings indicate that lung volume excursions about the midrange of vital capacity elicit a greater area of chest wall intermuscular coherence compared with lung volume excursions spanning the entire range of vital capacity in healthy adults. Our findings also demonstrate that brief tDCS may modulate the cortical control of the chest wall muscles in a stimulation- and lung volume excursion task-dependent manner but does not affect chest wall kinematics in healthy adults.