Wireless Sensing of Lower Lip and Thumb-Index Finger 'Ramp-and-Hold' Isometric Force Dynamics in a Small Cohort of Unilateral MCA Stroke: Discussion of Preliminary Findings.

Automated wireless sensing of force dynamics during a visuomotor control task was used to rapidly assess residual motor function during finger pinch (right and left hand) and lower lip compression in a cohort of seven adult males with chronic, unilateral middle cerebral artery (MCA) stroke with infarct confirmed by anatomic magnetic resonance imaging (MRI). A matched cohort of 25 neurotypical adult males served as controls. Dependent variables were extracted from digitized records of 'ramp-and-hold' isometric contractions to target levels (0.25, 0.5, 1, and 2 Newtons) presented in a randomized block design; and included force reaction time, peak force, and dF/dtmax associated with force recruitment, and end-point accuracy and variability metrics during the contraction hold-phase (mean, SD, criterion percentage 'on-target'). Maximum voluntary contraction force (MVCF) was also assessed to establish the force operating range. Results based on linear mixed modeling (LMM, adjusted for age and handedness) revealed significant patterns of dissolution in fine force regulation among MCA stroke participants, especially for the contralesional thumb-index finger followed by the ipsilesional digits, and the lower lip. For example, the contralesional thumb-index finger manifest increased reaction time, and greater overshoot in peak force during recruitment compared to controls. Impaired force regulation among MCA stroke participants during the contraction hold-phase was associated with significant increases in force SD, and dramatic reduction in the ability to regulate force output within prescribed target force window (±5% of target). Impaired force regulation during contraction hold-phase was greatest in the contralesional hand muscle group, followed by significant dissolution in ipsilateral digits, with smaller effects found for lower lip. These changes in fine force dynamics were accompanied by large reductions in the MVCF with the LMM marginal means for contralesional and ipsilesional pinch forces at just 34.77% (15.93 N vs. 45.82 N) and 66.45% (27.23 N vs. 40.98 N) of control performance, respectively. Biomechanical measures of fine force and MVCF performance in adult stroke survivors provide valuable information on the profile of residual motor function which can help inform clinical treatment strategies and quantitatively monitor the efficacy of rehabilitation or neuroprotection strategies.

Acoustics of Emotional Prosody Produced by Prelingually Deaf Children With Cochlear Implants.

Purpose: Cochlear implants (CIs) provide reasonable levels of speech recognition quietly, but voice pitch perception is severely impaired in CI users. The central question addressed here relates to how access to acoustic input pre-implantation influences vocal emotion production by individuals with CIs. The objective of this study was to compare acoustic characteristics of vocal emotions produced by prelingually deaf school-aged children with cochlear implants (CCIs) who were implanted at the age of 2 and had no usable hearing before implantation with those produced by children with normal hearing (CNH), adults with normal hearing (ANH), and postlingually deaf adults with cochlear implants (ACI) who developed with good access to acoustic information prior to losing their hearing and receiving a CI. Method: A set of 20 sentences without lexically based emotional information was recorded by 13 CCI, 9 CNH, 9 ANH, and 10 ACI, each with a happy emotion and a sad emotion, without training or guidance. The sentences were analyzed for primary acoustic characteristics of the productions. Results: Significant effects of Emotion were observed in all acoustic features analyzed (mean voice pitch, standard deviation of voice pitch, intensity, duration, and spectral centroid). ACI and ANH did not differ in any of the analyses. Of the four groups, CCI produced the smallest acoustic contrasts between the emotions in voice pitch and emotions in its standard deviation. Effects of developmental age (highly correlated with the duration of device experience) and age at implantation (moderately correlated with duration of device experience) were observed, and interactions with the children's sex were also observed. Conclusion: Although prelingually deaf CCI and postlingually deaf ACI are listening to similar degraded speech and show similar deficits in vocal emotion perception, these groups are distinct in their productions of contrastive vocal emotions. The results underscore the importance of access to acoustic hearing in early childhood for the production of speech prosody and also suggest the need for a greater role of speech therapy in this area.

Orofacial and thumb-index finger ramp-and-hold isometric force dynamics in young neurotypical adults.

The relation among several parameters of the ramp-and-hold isometric force contraction (peak force and dF/dtmax during the initial phase of force recruitment, and the proportion of hold-phase at target) was quantified for the right and left thumb-index finger pinch, and lower lip midline compression in 40 neurotypical right-handed young adults (20 female/20 males) using wireless force sensors and data acquisition technology developed in our laboratory. In this visuomotor control task, participants produced ramp-and-hold isometric forces as 'rapidly and accurately' as possible to end-point target levels at 0.25, 0.5, 1 and 2 Newtons presented to a computer monitor in a randomized block design. Significant relations were found between the parameters of the ramp-and-hold lip force task and target force level, including the peak rate of force change (dF/dtmax), peak force, and the criterion percentage of force within ±5% of target during the contraction hold phase. A significant performance advantage was found among these force variables for the thumb-index finger over the lower lip. The maximum voluntary compression force (MVCF) task revealed highly significant differences in force output between the thumb-index fingers and lower lip (∼4.47-4.70 times greater for the digits versus lower lip), a significant advantage of the right thumb-index finger over the non-dominant left thumb-index finger (12% and 25% right hand advantage for males and females, respectively), and a significant sex difference (∼1.65-1.73 times greater among males).

In vivo lateral blood flow velocity measurement using speckle size estimation.

In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method across a field of view and combination with an appropriate axial flow estimator.