Specific tasks expose constraints on social exploration and ultrasonic vocalisation production in male C57BL/6J mice.

Mice are widely studied for investigation of the mechanisms underlying sociability. Our understanding of the preferences, persistence and sensitivity of mouse social exploration to different sensory modalities is growing but studies report inconsistent social preferences in the C57BL/6 J strain, which is very commonly employed in studies of behavioural genetics. Herein, a battery of socially-relevant choice tasks were performed to assess the propensity of adult male C57BL/6 J mice to engage in exploration under various settings and emit ultrasonic vocalisations. With sex and age-matched conspecifics, the mice displayed preferences for social stimuli over objects and neutral odours; but the strength and persistence of this preferential exploration was time and affective state dependant. Importantly, under the commonly used social three-chamber assay very few vocalisations were detected, highlighting a limitation of the task for ultrasonic vocalisation-based social communication studies. In contrast, complex ultrasonic vocalisations and robust interactions were recorded in the free-interaction habituation / dishabituation task. These results demonstrate the modulation of ultrasonic production by task design, and highlight the sensitivity of social exploration measurements to the degrees of acoustic, olfactory and sensory complexity of the task stimuli.