Faculty mentor/PI email address
gouldf@rowan.edu
Keywords
Parkinson's disease, dysphagia
Date of Presentation
5-6-2026 12:00 AM
Poster Abstract
In Parkinson’s disease, the loss of dopaminergic neurons in the substantia nigra can cause dysphagia, which affects all phases of swallowing. In swallowing, bilateral pairs of muscles under the control of independent unilateral neural mechanisms must simultaneously activate to coordinate their movements and produce a swallow. However it is unknown how Parkinson’s disease impairs the activation of the right and left sides of those muscles. In this study we tested how Parkinson’s disease impacts the lateralization of the digastric muscle in rats. We hypothesized that Parkinson’s disease will cause a difference in activation of the right and left digastric muscles during feeding behaviors. We injected four male rats with rotenone over 16 days to induce Parkinson’s disease and recorded electromyography (EMG) with simultaneous videofluoroscopy while the rats ate and drank food and water mixed with barium. Chewing cycles and swallows were identified from the videofluoroscopic recordings and corresponding EMG sequences with strong digastric signals were extracted. EMG data was rectified, integrated, and baseline corrected prior to analysis using R. Using timings from synchronized high speed videofluoroscopy, individual chewing and licking cycles were identified. In the EMG data, duration of right and left digastric activity was measured for each chewing or licking cycle. Linear mixed models with individual as a random factor tested for the effect of side, treatment group, and their interaction on duration of digastric activity in chewing and drinking. Planned post hoc contracts tests identified significant pairwise differences. On Day 16 the control animals showed no difference in the duration of activation of the left versus right digastric during chewing (p = 0.08), but in the treated animals there was a significant increase in duration of activation of the right digastric compared to the left (p < 0.01). Rotenone treatment caused a unilateral increase in duration of right digastric activation in chewing solid food, suggesting the deficits from rotenone-induced Parkinson’s disease were more localized to the right digastric muscle. This could reflect a disruption in the simultaneous activation of the digastric muscle, given the reduction in chewing velocity of the right digastric muscle. On Day 16 the control animals also showed no difference in duration of left versus right digastric activation during drinking (p = 0.3), but in the treated animals there was a significant decrease in duration of activation of the left digastric compared to the right (p < 0.03). Drinking requires simpler jaw movements compared to chewing, so it is possible that the left digastric muscle is not recruited as much in drinking and is activated less than the right digastric. These variations in the activation of the right and left digastric muscles could indicate a Parkinson’s induced change to the neural mechanisms underlying the digastric’s role in swallowing.
Disciplines
Medicine and Health Sciences | Nervous System Diseases
Included in
Effect of Parkinson’s Disease on the lateralization of the digastric muscle in a rodent model
In Parkinson’s disease, the loss of dopaminergic neurons in the substantia nigra can cause dysphagia, which affects all phases of swallowing. In swallowing, bilateral pairs of muscles under the control of independent unilateral neural mechanisms must simultaneously activate to coordinate their movements and produce a swallow. However it is unknown how Parkinson’s disease impairs the activation of the right and left sides of those muscles. In this study we tested how Parkinson’s disease impacts the lateralization of the digastric muscle in rats. We hypothesized that Parkinson’s disease will cause a difference in activation of the right and left digastric muscles during feeding behaviors. We injected four male rats with rotenone over 16 days to induce Parkinson’s disease and recorded electromyography (EMG) with simultaneous videofluoroscopy while the rats ate and drank food and water mixed with barium. Chewing cycles and swallows were identified from the videofluoroscopic recordings and corresponding EMG sequences with strong digastric signals were extracted. EMG data was rectified, integrated, and baseline corrected prior to analysis using R. Using timings from synchronized high speed videofluoroscopy, individual chewing and licking cycles were identified. In the EMG data, duration of right and left digastric activity was measured for each chewing or licking cycle. Linear mixed models with individual as a random factor tested for the effect of side, treatment group, and their interaction on duration of digastric activity in chewing and drinking. Planned post hoc contracts tests identified significant pairwise differences. On Day 16 the control animals showed no difference in the duration of activation of the left versus right digastric during chewing (p = 0.08), but in the treated animals there was a significant increase in duration of activation of the right digastric compared to the left (p < 0.01). Rotenone treatment caused a unilateral increase in duration of right digastric activation in chewing solid food, suggesting the deficits from rotenone-induced Parkinson’s disease were more localized to the right digastric muscle. This could reflect a disruption in the simultaneous activation of the digastric muscle, given the reduction in chewing velocity of the right digastric muscle. On Day 16 the control animals also showed no difference in duration of left versus right digastric activation during drinking (p = 0.3), but in the treated animals there was a significant decrease in duration of activation of the left digastric compared to the right (p < 0.03). Drinking requires simpler jaw movements compared to chewing, so it is possible that the left digastric muscle is not recruited as much in drinking and is activated less than the right digastric. These variations in the activation of the right and left digastric muscles could indicate a Parkinson’s induced change to the neural mechanisms underlying the digastric’s role in swallowing.