Vocal Training Mitigates Age-Related Changes Within the Vocal Mechanism in Old Rats

Abstract

Aging affects voice production and is associated with reduced communicative ability and quality of life. Voice therapy is a critical component of treatment, but its effects on neuromuscular mechanisms are unknown. The ultrasonic vocalizations (USVs) of rats can be used to test the effects of aging and voice use on the laryngeal neuromuscular system. This study tested the hypothesis that age-related changes in the USVs of rats and laryngeal neuromuscular junctions can be reversed through vocal exercise. Young and old rats were trained for 8 weeks to increase their USVs and were compared with a no intervention group pre- and post-treatment. USV acoustics and aspects of neuromuscular junction (NMJ) morphology were measured in the thyroarytenoid muscle. Vocal training reduced or eliminated some age differences found in both USVs and NMJs. We conclude that vocal exercise may assist in mitigating age-related changes in voice characteristics and underlying neuromuscular adaptations.

Cross-activation and detraining effects of tongue exercise in aged rats

“…Our findings were similar to age-related changes reported in previous studies examining aging rat vocalizations (Basken, et al, 2012,Johnson, et al, 2013), including reduced number of calls, increased duration, and decreased intensity in old versus young adult groups. In the Basken study, these age-related behavioral changes were correlated with significant motor neuron loss in the NA (Basken, et al, 2012).…”

“…Spectrograms were built from each waveform with the frequency resolution set to an FFT of 512 points, frame size of 100%, flat top window, and the temporal resolution set to display 75 % overlap. (For video example and review of previous studies, see Ciucci, et al, 2009,Johnson, et al, 2013,Johnson, et al, 2011). …”

Aging voice and the laryngeal muscle atrophy

“…Voice therapy for presbyphonia has proved to be effective in improving glottic incompetence and vocal performance in the elderly . Johnson et al studied the effects of voice therapy on neuromuscular mechanisms in rats using the ultrasonic vocalizations. In this study, young and old Fischer 344/Brown Norway male rats were trained during 8 weeks to increase their ultrasonic vocalization.…”

Social isolation alters ultrasonic vocalizations but not thyroarytenoid neuromuscular junctions in old rats

“…Likewise, the thyroarytenoid (TA) muscle undergoes atrophic changes in advanced age accompanied by alterations of NMJ morphology . Additionally, functional age‐related vocalization deficits, such as a decrease in the amplitude of the ultrasonic vocalizations (USVs) of old rats, have been associated with increased NMJ motor endplate dispersion in a normally aging rat model . Thus, changes in NMJ morphology are related to structural and functional sarcopenic changes.…”