The effect of neurodegeneration on ultrasonic vocalisations (USV) and their neuronal substrates in mice and rats: A systematic review.

Neurodegenerative diseases, such as Parkinson's, Alzheimer's, and Frontotemporal Degeneration, significantly impair communication abilities in humans. Animal models, particularly rats and mice, are widely used to study the underlying mechanisms of these disorders. Ultrasonic vocalisations (USVs) play a crucial role in signalling emotional states during social interaction, mating, and distress and may reflect low versus high arousal and/or a positive versus negative affective state of the animal, making them valuable behavioural biomarkers for neurological dysfunction. This systematic review synthesises the existing literature on USVs in rodent models of neurodegeneration. Specifically, it compares USV alterations across disease models, summarises the experimental paradigms used to elicit USVs, and reviews the neurobiological findings reported alongside these vocal changes. By integrating findings across studies, this review highlights consistent patterns, methodological differences, and current knowledge gaps to guide future research. Studying USV impairments in animal models may help to neurobiologically validate biomarkers based on the detection of acoustic changes in the vocal output of patients with neurodegenerative diseases. By bridging the gap between preclinical and clinical research, this review aims to contribute to the growing field of neurobehavioral biomarkers, which could ultimately improve early diagnosis and intervention in human neurodegenerative conditions.