iScience· 2026Q1
Positive emotional contagion by laughter-like 50-kHz ultrasonic vocalizations in rats
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- Q1SCImago
- 2026year
Short summary
Rats exhibit positive emotional contagion when exposed to 50-kHz ultrasonic vocalizations (USVs), which are analogous to laughter, as evidenced by a significant attenuation of their acoustic startle response (ASR).
AI-generated from the title and abstract; the full text is not read.
Key points
- Rats show positive emotional contagion via 50-kHz ultrasonic vocalizations (USVs), similar to laughter.
- Exposure to 50-kHz USVs significantly attenuated the acoustic startle response (ASR) in receiver rats.
- 22-kHz USVs, associated with negative affect, did not attenuate the ASR.
- The study developed a new paradigm using USVs and ASR to measure positive emotional contagion.
AI-generated from the title and abstract; the full text is not read.
Abstract
Rats display advanced empathic abilities, yet current research is focused on empathy toward negative affect, largely neglecting positive affective states. We therefore developed a paradigm suitable for assessing both negative and positive emotional contagion. It relies on ethotransmission (i.e., acoustic emotional communication) of affective states to conspecifics via ultrasonic vocalizations (USV), i.e., alarming 22-kHz USV (negative affect) and laughter-like 50-kHz USV (positive affect). Specifically, we subjected rats to playback of 22-kHz or 50-kHz USV, while assessing their acoustic startle response (ASR), which is known to be emotionally modulated (i.e., potentiated and attenuated by negative and positive affect, respectively). Here, 50-kHz but not 22-kHz USV strongly attenuated the ASR across sexes and development, suggesting that laughter-like 50-kHz USV induced positive affect in receivers, indicative of positive emotional contagion. Our paradigm provides the first quantitative assessment of positive emotional contagion in rats through capitalizing on ethological signals (USV) and simple reflexes (ASR).
The authors' abstract, as published at the source. iScience, 2026 · DOI ↗
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Developmental BiologyBiochemistry, Genetics and Molecular Biology