High-precision spatial analysis of mouse courtship vocalization behavior reveals sex and strain differences

Abstract

Mice display a wide repertoire of vocalizations that varies with sex, strain, and context. Especially during social interaction, mice emit sequences of ultrasonic vocalizations (USVs) of high complexity. As animals of both sexes vocalize, a reliable attribution of USVs to their emitter is essential. The state-of-the-art in sound localization for USVs in 2D allows spatial localization at a resolution of multiple centimeters. However, animals interact at closer ranges, e.g. snout-to-snout. Hence, improved algorithms are required to reliably assign USVs. We present a novel algorithm, SLIM (Sound Localization via Intersecting Manifolds), that achieves a 3-fold improvement in accuracy (12-14.3mm) using only 4 microphones and extends to many microphones and localization in 3D. This accuracy allows reliable assignment of 84.3% of all USVs in our dataset. We apply SLIM to courtship interactions between adult C57Bl/6J wildtype mice and those carrying a heterozygous Foxp2 variant (R552H). The improved spatial accuracy reveals detailed vocalization preferences for specific spatial relations between the mice. Specifically, vocalization probability, duration, Wiener entropy, and frequency level differed in particular spatial relations between WT females, Foxp2-R552H and WT males. In conclusion, the improved attribution of vocalizations to their emitters provides a foundation for better understanding social vocal behaviors.

Rodent ultrasonic vocal interaction resolved with millimeter precision using hybrid beamforming

“…S2). The USM4 data is analyzed using our SLIM algorithm, 73 which delivers accurate (MAE = ~11-14 mm) and less frequency-limited estimates. The methods exhibit a complementary pattern of localization errors, which predestines them for high synergy when combined (see below).…”

“…Compared to the previous state of the art 73,75 , the accuracy represents a three-fold improvement that halves the proportion of previously unassigned USVs. Given the physical dimensions of the mouse snout (ø~10 mm), this likely approaches the physical limit of localizability for USVs.…”

“…in mm's), we scaled them such that their average across all USVs matched the residual error of each method in the Far-condition (all animals >100 mm apart, see Fig. 3C and Oliveira-Stahl et al 73 ). In this way, the 𝑀𝑃𝐼 𝑘 for individual USVs took into account the uncertainty of each method: if the uncertainty of one method was higher, probabilities across mice would become more similar and the 𝑀𝑃𝐼 𝑘 would reduce.…”

“…In recent years, substantial advances have been made in USV detection [67][68][69][70][71] , classification 67,68,70,72 , and localization. [73][74][75][76] Localization is of particular importance during social interactions, when most USVs are emitted and any meaningful analysis of USV properties rests on a reliable assignment of each USV to its emitter. This task is complex for multiple reasons: (i) most USVs are emitted at close range, (ii) social behavior often requires free movement of the animals, and (iii) USV production is invisible.…”

Hearing, touching, and multisensory integration during mate choice

“…Pheromones may be the most important modality for the initial approach, but they are most certainly not acting in isolation (Asaba et al, 2014 , 2017 ; Ågmo and Snoeren, 2017 ; Haskal de la Zerda et al, 2020 ; Ronald et al, 2020 ; Zala et al, 2020 ; Contestabile et al, 2021 ). However, it has been hard to unravel the role of other cues in mate choice; controversy surrounds the role of calls for example, in part due to the difficulty of identifying who says what, an obstacle that was overcome by recent technical advances (Binder et al, 2020 ) in the capacity to locate sound sources (Neunuebel et al, 2015 ; Heckman et al, 2017 ; Warren et al, 2018 ; Coffey et al, 2019 ; Sangiamo et al, 2020 ; Oliveira-Stahl et al, 2021 ). Hence, recent studies in mice (Asaba et al, 2017 ; Ronald et al, 2020 ; Warren et al, 2020 ) made important progress towards investigating the role of sound communication during various socio-sexual behaviors (Sangiamo et al, 2020 ) and found that specific calls in the ultrasound range (named ultrasonic vocalizations, USVs) are expressed by males and females during mating (Holy and Guo, 2005 ; Potfors and Perkel, 2014 ; Heckman et al, 2016 ; Seagraves et al, 2016 ; Asaba et al, 2017 ; Matsumoto and Okanoya, 2018 ; Niemczura et al, 2020 ; Ronald et al, 2020 ; Warren et al, 2020 ).…”