Objective physiological measures of lingual and jaw function in healthy individuals and individuals with dysphagia due to neurodegenerative diseases.

Swallowing is a neuromuscular process that involves a complex sequence of sensorimotor events, which are executed to efficiently and safely transport food and liquid from the mouth to the stomach. Safe oropharyngeal swallowing involves the activation, modulation, and coordination of oral, pharyngeal, laryngeal, and esophageal structures and musculature. Impaired or atypical patterns of swallowing are considered characteristic of a swallowing disorder, otherwise referred to as dysphagia, and affect the performance of all stages, i.e., oral preparatory, oral transit, pharyngeal, and esophageal. Lingual and jaw musculature play critical roles in mediating swallowing function, particularly during the oral preparatory and oral transit stages. This current study presents an adapted simple, economical, and clinically relevant protocol that may be used to quantify lingual and jaw movement in healthy and disordered swallowing, and thus track physiological changes in lingual and jaw musculature over time in individuals with dysphagia due to neurodegenerative diseases.•Jaw ROM tasks, adapted from [1,2], were adapted and utilized to measure the jaw during three postures: opening, lateralization, and protrusion.•Adapting a scale developed by Lazarus and colleagues [3], objective lingual ROM values were obtained using the TheraBiteⓇ tool [4] and categorized according to functional status.•Upon methodological adaption and collation of lingual ROM and jaw ROM tasks, a comprehensive set of images clearly depicting each procedural task and a clinically friendly form were developed to guide data collection for research and clinical use.

Objective measures of lingual and jaw function in healthy adults and persons with Parkinson's disease: Implications for swallowing.

The study examines the effects of age and Parkinson's disease on lingual and jaw function in neurotypical adults, as well as persons with Parkinson's Disease. Preliminary results provide reference measures in these populations and support the systematic collection of objective data regarding lingual strength, lingual range of motion, and jaw range of motion in clinical populations. The application of this clinically meaningful protocol also provides a means to track physiological changes over time in order to maximize the results of rehabilitative efforts to restore swallow function.

Predictive value of laryngeal adductor reflex testing in patients with dysphagia due to a cerebral vascular accident.

Purpose: To determine the relationship between air pulse vs. touch laryngeal adductor reflex (LAR) tests and the clinical sensory findings of fiberoptic endoscopic evaluations of swallowing.Method: A retrospective review was conducted for 43 patients with dysphagia due to stroke that underwent fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST). Each patient received LAR testing using air pulse or touch methodologies. Clinically, responsiveness to pharyngeal residue and responsiveness to penetration or aspiration were analysed.Result: The sensitivity, specificity, positive and negative predictive values for both LAR test groups indicate that LAR testing did not effectively predict sensory function during the clinical swallow evaluation. Across both LAR groups, specificity values were higher than sensitivity values. In fact, the specificity values for the light touch LAR test group were extremely high, but the negative predictive values did not support those findings. Sensitivity and positive predictive values were low for both groups.Conclusion: Although LAR testing provides valuable information regarding laryngeal sensory discrimination, the results of the current study suggest that a clinical evaluation of swallowing is critical for effectively assessing the way in which patients utilise sensory information during swallowing.

Time-Frequency Analysis of Mu Rhythm Activity during Picture and Video Action Naming Tasks.

This study used whole-head 64 channel electroencephalography to measure changes in sensorimotor activity-as indexed by the mu rhythm-in neurologically-healthy adults, during subvocal confrontation naming tasks. Independent component analyses revealed sensorimotor mu component clusters in the right and left hemispheres. Event related spectral perturbation analyses indicated significantly stronger patterns of mu rhythm activity ( p FDR < 0.05) during the video condition as compared to the picture condition, specifically in the left hemisphere. Mu activity is hypothesized to reflect typical patterns of sensorimotor activation during action verb naming tasks. These results support further investigation into sensorimotor cortical activity during action verb naming in clinical populations.

Temporal dynamics of sensorimotor integration in speech perception and production: independent component analysis of EEG data.

Activity in anterior sensorimotor regions is found in speech production and some perception tasks. Yet, how sensorimotor integration supports these functions is unclear due to a lack of data examining the timing of activity from these regions. Beta (~20 Hz) and alpha (~10 Hz) spectral power within the EEG µ rhythm are considered indices of motor and somatosensory activity, respectively. In the current study, perception conditions required discrimination (same/different) of syllables pairs (/ba/ and /da/) in quiet and noisy conditions. Production conditions required covert and overt syllable productions and overt word production. Independent component analysis was performed on EEG data obtained during these conditions to (1) identify clusters of µ components common to all conditions and (2) examine real-time event-related spectral perturbations (ERSP) within alpha and beta bands. 17 and 15 out of 20 participants produced left and right µ-components, respectively, localized to precentral gyri. Discrimination conditions were characterized by significant (pFDR < 0.05) early alpha event-related synchronization (ERS) prior to and during stimulus presentation and later alpha event-related desynchronization (ERD) following stimulus offset. Beta ERD began early and gained strength across time. Differences were found between quiet and noisy discrimination conditions. Both overt syllable and word productions yielded similar alpha/beta ERD that began prior to production and was strongest during muscle activity. Findings during covert production were weaker than during overt production. One explanation for these findings is that µ-beta ERD indexes early predictive coding (e.g., internal modeling) and/or overt and covert attentional/motor processes. µ-alpha ERS may index inhibitory input to the premotor cortex from sensory regions prior to and during discrimination, while µ-alpha ERD may index sensory feedback during speech rehearsal and production.

Suppression of the µ rhythm during speech and non-speech discrimination revealed by independent component analysis: implications for sensorimotor integration in speech processing.

BACKGROUND: Constructivist theories propose that articulatory hypotheses about incoming phonetic targets may function to enhance perception by limiting the possibilities for sensory analysis. To provide evidence for this proposal, it is necessary to map ongoing, high-temporal resolution changes in sensorimotor activity (i.e., the sensorimotor µ rhythm) to accurate speech and non-speech discrimination performance (i.e., correct trials.). METHODS: Sixteen participants (15 female and 1 male) were asked to passively listen to or actively identify speech and tone-sweeps in a two-force choice discrimination task while the electroencephalograph (EEG) was recorded from 32 channels. The stimuli were presented at signal-to-noise ratios (SNRs) in which discrimination accuracy was high (i.e., 80-100%) and low SNRs producing discrimination performance at chance. EEG data were decomposed using independent component analysis and clustered across participants using principle component methods in EEGLAB. RESULTS: ICA revealed left and right sensorimotor µ components for 14/16 and 13/16 participants respectively that were identified on the basis of scalp topography, spectral peaks, and localization to the precentral and postcentral gyri. Time-frequency analysis of left and right lateralized µ component clusters revealed significant (pFDR<.05) suppression in the traditional beta frequency range (13-30 Hz) prior to, during, and following syllable discrimination trials. No significant differences from baseline were found for passive tasks. Tone conditions produced right µ beta suppression following stimulus onset only. For the left µ, significant differences in the magnitude of beta suppression were found for correct speech discrimination trials relative to chance trials following stimulus offset. CONCLUSIONS: Findings are consistent with constructivist, internal model theories proposing that early forward motor models generate predictions about likely phonemic units that are then synthesized with incoming sensory cues during active as opposed to passive processing. Future directions and possible translational value for clinical populations in which sensorimotor integration may play a functional role are discussed.

Mu suppression as an index of sensorimotor contributions to speech processing: evidence from continuous EEG signals.

Mu rhythm suppression is an index of sensorimotor activity during the processing of sensory stimuli. Two present studies investigate the extent to which this measure is sensitive to differences in acoustic processing. In both studies, participants were required to listen to 90second acoustic stimuli clips with their eyes closed and identify predetermined targets. Experimental conditions were designed to vary the acoustic processing demands. Mu suppression was measured continuously across central electrodes (C3, Cz, and C4). Ten adult females participated in the first study in which the target was a pseudoword presented in three conditions (identification, discrimination, discrimination in noise). Mu suppression was strongest and reached significance relative to baseline only in the discrimination in noise task at C3 (indicative of left hemisphere sensorimotor activity) when measured in a 10-12Hz bandwidth. Thirteen adult females participated in the second study, which measured mu suppression to acoustic stimuli with 'segmentation' (i.e., separating a parsed stimulus into individual components) versus non-segmentation requirements in both speech and tone discrimination conditions. Significantly greater overall suppression to speech relative to tone tasks was found in the 10-12Hz bandwidth. Further, suppression relative to baseline was significant only at C3 during the speech discrimination with segmentation task. Taken together, findings indicate that mu rhythm suppression in acoustic processing is sensitive to dorsal stream processing. More specifically, it is sensitive to (1) increases in overall processing demands and (2) processing linguistic versus non-linguistic information.