Rodent ultrasonic vocalizations are bound to active sniffing behavior

Area of Science:

• Neuroscience
• Behavioral Biology
• Animal Communication

Background:

• Rodent orofacial behaviors like sniffing and whisking exhibit theta-range rhythmicity (~5-10 Hz) during active behavior.
• These rhythmic patterns can interlock, making motor program execution state-dependent.

Purpose of the Study:

• To investigate the relationship between breathing patterns and ultrasonic vocalization (USV) emission in rats and mice during social interactions.
• To determine if USVs are integrated into the rhythmic orofacial behavioral ensemble and contribute to temporal structuring of communication.

Main Methods:

• Simultaneous recording of respiratory cycles and ultrasonic vocalization (50 kHz USVs) in adult rats and mice in social settings.
• Automated analysis to examine long-term relationships between breathing patterns and vocalization.

Main Results:

• Rat USVs were predominantly emitted during active sniffing (5-10 Hz) and absent during passive breathing (1-4 Hz).
• USV emission was tightly linked to the exhalation phase, with sniffing cycles segmenting vocal production and imposing theta rhythmicity.
• USVs briefly prolonged exhalations, leading to an immediate decrease in sniffing rate, a phenomenon also observed in mice.

Conclusions:

• Ultrasonic vocalizations are an integral component of the rhythmic orofacial behavioral ensemble in rodents.
• This behavioral program not only facilitates active sensing but also plays a crucial role in the temporal structuring of social communication signals.
• The findings suggest a potential mechanism for theta-range structuring observed in various mammalian social signals, including human speech.