Breslav, D. | Search bioRxiv

bioRxiv2025

Separation slang - Laboratory mice use low-frequency call repertoire during physical separation

The discovery of a diverse repertoire of ultrasonic vocalizations (USVs) sparked interest in understanding their role in mouse social behavior. Social communication in mice is not just vocal, but multimodal and occurs mostly in close proximity. Aiming to unravel the impact direct physical interaction has on the vocal communication of same-sex mouse dyads, we separated mice through a divider preventing direct physical interaction, but allowing visual, olfactory and some tactile interaction through holes. Separated dyads emitted a distinct call repertoire consisting mainly of calls in or just above the human audible range (but not squeaks) as well as Noisy calls, and only to a lesser degree of USVs. Increasing the possibility for direct interaction through larger holes in the divider led to an adaption of the call repertoire. The separation-induced call repertoire was neither affected by sex, nor was it mouse strain specific, even though differences in spectro-temporal parameters and call class proportion occurred. Lastly, buspirone treatment showed no observable effect, suggesting anxiety to not be the main driver underlying the separation-induced call repertoire. We show that separated same-sex mouse dyads predominantly emit a call repertoire that until now has only been observed in isolation or during aversive stimulation.

animal behavior and cognition↗

bioRxiv2024

An improved isochronous pulse after lentiviral knock-down of STEP in Area X of juvenile zebra finches

The zebra finch is one of the most commonly used animal models for studying the genetic mechanisms underlying vocal learning. To investigate the genetic basis of vocal learning, various genes have been knocked down in Area X--a brain region involved in birdsong acquisition--during the critical learning period. All genes that affect speech when mutated in humans similarly impair song learning in zebra finches. To date, no study has demonstrated that not all genes downregulated in Area X result in decreased song learning. Therefore, we sought a candidate gene to knock down in Area X that could either have no effect or potentially improve song learning. STEP is a protein that dephosphorylates many targets in the brain, and its knockout in mice has resulted in enhanced learning. In this study, a lentiviral knockdown of STEP in Area X during song learning resulted in birds producing normal song in almost all parameters and levels of song analysis. This stands in contrast to the knockdown of other genes like all FoxP subfamily members, which resulted in diminished song learning in previous studies. The only parameter positively affected by STEP knockdown was song rhythmicity, as evidenced by a lower deviation of song element onsets from an isochronous pulse than even their tutors. These results demonstrate for the first time that not all knockdowns in Area X lead to deterioration of song learning and validate the specificity of the method and previous findings. Significance StatementThis is the first coding gene knockdown in Area X without negatively affecting song learning.

animal behavior and cognition↗