Abstract
Mice produce ultrasonic vocalizations (USVs) in a variety of social situations, and USVs have been leveraged to study many neurological diseases including verbal dyspraxia, depression, autism and stuttering. Pups produce isolation calls, a common USV, spontaneously when they are isolated from their mother during the first 2 weeks of life. Several genetic manipulations affect (and often reduce) pup isolation calls in mice. To facilitate the use of this assay as a means of testing whether significant functional differences in genotypes exist instead of contextual differences, we test the variability inherent in many commons measures of mouse vocalizations. Here we use biological consistency as a way of determining which are reproducible in mouse pup vocalizations. We present a comprehensive analysis of the normal variability of these vocalizations in groups of mice, individual mice and different strains of mice. To control for maturation effects, we recorded pup isolation calls in the same group of C57BL/6J 5 days old mice twice, with 1 h of rest in between recordings. In almost all cases, the group averages between the first and second recordings were the same. We also found that there were high correlations in some parameters in individual mice across recording while others were not well correlated. These findings could be replicated for the majority of features in a separate group of C57BL/6J mice and a group of 129/SvEvBrd-C57BL/6J mice. The averages of these mouse USV features are highly consistent and represent a robust assay to test the effects of genetic and other interventions in the experimental setting.
Highlights
Mouse ultrasonic vocalizations (USVs) are a recognized assay of neurological function in mice and reflect the animal’s cognitive and social state (Branchi et al, 2001; Hofer et al, 2002; Fisher et al, 2003; Liu et al, 2003; Scattoni et al, 2009; Hammerschmidt et al, 2012)
Pup isolation calls are affected by a wide variety of genetic manipulations (Nastiti et al, 1991; Nelson and Panksepp, 1998; Weller et al, 2003; Antonelli et al, 2005; Takayanagi et al, 2005; Scattoni et al, 2008) that often decrease the vocalization number (Nastiti et al, 1991; Nelson and Panksepp, 1998; Branchi et al, 2001; Fischer and Hammerschmidt, 2010; Gaub et al, 2010)
Understanding and recognizing natural variability is crucial when interpreting many USV features including call rate, pitch jump and power over several days but that most USV features were consistent within a single recording session
Summary
Mouse ultrasonic vocalizations (USVs) are a recognized assay of neurological function in mice and reflect the animal’s cognitive and social state (Branchi et al, 2001; Hofer et al, 2002; Fisher et al, 2003; Liu et al, 2003; Scattoni et al, 2009; Hammerschmidt et al, 2012). In contrast Gaub et al (2010) showed there was no effect in mice heterozygous for the Foxp S321X nonsense mutation that representing a null allele. Another disorder that has been explored utilizing USVs in mutant mice is autism. Understanding and recognizing natural variability is crucial when interpreting many USV features including call rate, pitch jump and power over several days (i.e., during critical early maturation) but that most USV features were consistent within a single recording session. The averages of these mouse vocalization features are generally consistent, and recording USVs in mouse pups represents a robust assay to test the effects of genetic and other interventions in the experimental setting
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