Laurel A. Screven

Discrimination of frequency modulated sweeps by mice

Mice often produce ultrasonic vocalizations (USVs) that sweep upwards in frequency from around 60 to around 80 kHz and downwards in frequency from 80 to 60 kHz. Whether or not these USVs are used for communication purposes is still unknown. Here, mice were trained and tested using operant conditioning procedures and positive reinforcement to discriminate between synthetic upsweeps and downsweeps. The stimuli varied in bandwidth, duration, and direction of sweep. The mice performed significantly worse when discriminating between background and test stimuli when the stimuli all occupied the same bandwidths. Further, the mices discrimination performance became much worse for stimuli that had durations similar to those natural vocalizations of the mice. Sweeps composed of different frequency ranges and longer durations had improved discrimination. These results collected using artificial stimuli created to mimic natural USVs indicate that the bandwidth of the vocalizations may be much more important for communication than the frequency contours of the vocalizations.

CBA/CaJ mouse ultrasonic vocalizations depend on prior social experience

Mouse ultrasonic vocalizations (USVs) have variable spectrotemporal features, which researchers use to parse them into different categories. USVs may be important for communication, but it is unclear whether the categories that researchers have developed are relevant to the mice. Instead, other properties such as the number, rate, peak frequency, or bandwidth of the vocalizations may be important cues that the mice are using to interpret the nature of the social interaction. To investigate this, a comprehensive catalog of the USVs that mice are producing across different social contexts must be created. Forty male and female adult CBA/CaJ mice were recorded in isolation for five minutes following either a one-hour period of isolation or an exposure to a same- or opposite-sex mouse. Vocalizations were separated into nine categories based on the frequency composition of each USV. Additionally, USVs were quantified based on the bandwidth, duration, peak frequency, total number, and proportion of vocalizations produced. Results indicate that mice differentially produce their vocalizations across social encounters. There were significant differences in the number of USVs that mice produce across exposure conditions, the proportional probability of producing the different categories of USVs across sex and conditions, and the features of the USVs across conditions. In sum, there are sex-specific differences in production of USVs by laboratory mice, and prior social experiences matter for vocalization production. Furthermore, this study provides critical evidence that female mice probably produce vocalizations in opposite-sex interactions, which is important because this is an often overlooked variable in mouse communication research.

Discrimination of frequency-modulated sweeps by laboratory mice

Mice often produce ultrasonic vocalizations (USVs) that sweep upwards in frequency from around 60 kHz to around 80 kHz, and similarly sweep downwards in frequency from 80 kHz to 60 kHz. Whether or not these USVs are used for communication purposes is still unknown. Determining the ability of mice to discriminate between synthetic upsweep and downsweep frequency-modulated stimuli will expand the current knowledge about acoustic communication in mice. Mice were trained and tested using operant conditioning procedures and positive reinforcement to discriminate between upsweeps and downsweeps. The stimuli varied in bandwidth, duration, and direction of the sweep. The animals responded when they heard a change in the repeating background, indicating that they could discriminate background from target. The mice performed significantly worse discriminating between background and targets when the stimuli occupied the same bandwidths. Further, the mice’s discrimination performance became much worse when the durati...

Rodent Vocalizations: Adaptations to Physical, Social, and Sexual Factors

This chapter introduces representative studies in acoustic communication in rodents. By using rodents as a model in which to study the evolution of vocal communication, researchers are able to utilize their diversity in physical habitats, social complexity, and sexual rituals. The widespread use of rodents as subjects of acoustic communication research is largely because many such species are the most successful mammalian group in terms of speciation. Much attention has been paid to isolation calls, alarm calls, and contact (or signature) calls in several species of rodents, with emphasis on the physical, social, and sexual variables involved in their production. Emergence of song-like vocalizations in both mother-infant contexts and male-female mating contexts are also discussed. Furthermore, the chapter focuses on the degree of plasticity in perception, production, and usage of these vocalizations in relation to the organization of neural structures related to hearing and vocalizations in rodents. Finally, these observations are integrated to suggest a general hypothesis on the evolution of vocal communication in rodents.

Hearing in Rodents

Hearing in rodents has been measured using both behavioral and physiological methods. Features of hearing that have been measured in rodents include auditory acuity in quiet and in noise, frequency selectivity and sensitivity, intensity resolution, temporal resolution, and complex sound perception. Generally, and especially for simple tone detection, behavioral thresholds are lower than physiological thresholds. Within behavioral studies, operant experiments using awake, behaving rodents produce lower thresholds than simple reflexive measures. Rodents generally have broader frequency filters than other mammals. Frequency and intensity resolution are similar but slightly elevated relative to other mammals. The few measures of complex sound perception performed to date show that at least some rodents have the capacity to distinguish between spectrotemporal characteristics of acoustic signals for communication. Most studies have typically employed domesticated laboratory rodents rather than wild-caught species, so few attempts have been made to correlate lifestyle and evolutionary history with auditory processing. Nonetheless, a baseline knowledge of hearing abilities in rodents will facilitate experiments on the perception of more complex, natural acoustic stimuli in the future.

Tinnitus related to physiological changes in the auditory nerve in chronically noise-exposed mice

Tinnitus is a pervasive auditory dysfunction affecting up to 10% of the adult population. The perception of ringing or hissing in the absence of a physical stimulus in one or both ears can be caused by acoustic trauma and other factors. Mice are a commonly used model for auditory disorders in humans, although the behavioral examination of tinnitus in mice has primarily been limited to reflexive measures involving inhibition of the acoustic startle by gaps in noise. Using an identification paradigm, we behaviorally tested whether mice show symptoms of tinnitus following long-term moderate noise exposure. Tinnitus was demonstrated by a shift in categorizing silence as narrowband noise. This experiment demonstrated that tinnitus can be induced in mice using noise exposure, similar to that caused by salicylate. Physiological and anatomical experiments reveal synaptic changes including response facilitation, increased reliability, increased synaptic terminal area, and increased number of release sites in mice ...

Ultrasonic vocalization production by socially isolated and experienced mice

Mice produce ultrasonic vocalizations (USVs) in a wide variety of social situations, including courtship, investigation, and territorial defense. Although production of USVs is believed to be innate, suggesting mice do not need acoustic experience with conspecifics to produce calls, it is possible mice require experience to emit calls in the proper behavioral context. Male mice require social experience with a female to produce USVs in response to olfactory signals present in dirty bedding (e.g., Nyby et al., 1983), and isolated male mice will produce more USVs than socially experienced males (Keesom et al., 2017), however the influence of social experience on vocal production by female mice has yet to be investigated. The present experiment aimed to determine if social isolation or experience with conspecifics influences the vocal repertoire of adult female CBA/CaJ mice. Mouse calls were recorded during exposure to an unknown male or female mouse and analyzed to determine if isolation or experience affected call number, rate, or spectrotemporal complexity. Chronic social isolation did influence the vocal repertoire, suggesting that social experience plays a role in the production of USVs by female mice.Mice produce ultrasonic vocalizations (USVs) in a wide variety of social situations, including courtship, investigation, and territorial defense. Although production of USVs is believed to be innate, suggesting mice do not need acoustic experience with conspecifics to produce calls, it is possible mice require experience to emit calls in the proper behavioral context. Male mice require social experience with a female to produce USVs in response to olfactory signals present in dirty bedding (e.g., Nyby et al., 1983), and isolated male mice will produce more USVs than socially experienced males (Keesom et al., 2017), however the influence of social experience on vocal production by female mice has yet to be investigated. The present experiment aimed to determine if social isolation or experience with conspecifics influences the vocal repertoire of adult female CBA/CaJ mice. Mouse calls were recorded during exposure to an unknown male or female mouse and analyzed to determine if isolation or experience affec...

Effects of numbers of repetitions, repetition rate, frequency separation, and frequency range on auditory streaming in budgerigars (Melopsittacus undulatus)

Auditory streaming has been widely investigated behaviorally and physiologically in animals. The paradigm used in European starlings (Sturnus vulgaris) by MacDougall-Shackleton and colleagues (1998, J. Acoust. Soc. Amer.) was used here in budgerigars (Melopsittacus undulatus) to measure the effects of different numbers of repetitions of HLH- (high and low tones) triplets, repetition rates, tone frequencies, and frequency separations between the two tones on auditory streaming. Similar to humans, budgerigars subjectively experienced the auditory streaming phenomenon; more repetitions of HLH- triplets, faster repetition rates, and larger frequency separations enhanced the streaming perception. Further, these results were consistent across the two frequency ranges used in this study. When increasing the numbers of HLH- repetitions, it took longer to establish the streaming perception in budgerigars, similar to the buildup phenomenon in humans. These results indicate, for the first time using a behavioral paradigm, that budgerigars experience auditory streaming in a manner similar to humans.Auditory streaming has been widely investigated behaviorally and physiologically in animals. The paradigm used in European starlings (Sturnus vulgaris) by MacDougall-Shackleton and colleagues (1998, J. Acoust. Soc. Amer.) was used here in budgerigars (Melopsittacus undulatus) to measure the effects of different numbers of repetitions of HLH- (high and low tones) triplets, repetition rates, tone frequencies, and frequency separations between the two tones on auditory streaming. Similar to humans, budgerigars subjectively experienced the auditory streaming phenomenon; more repetitions of HLH- triplets, faster repetition rates, and larger frequency separations enhanced the streaming perception. Further, these results were consistent across the two frequency ranges used in this study. When increasing the numbers of HLH- repetitions, it took longer to establish the streaming perception in budgerigars, similar to the buildup phenomenon in humans. These results indicate, for the first time using a behavioral par...

Preference in female laboratory mice is influenced by social experience

Mice must perceive and interpret the signals they are presented with to evaluate potential mates, and should show a preference for high quality conspecifics. The present experiment was designed to investigate preference for acoustic, olfactory, and acoustic + olfactory signals in laboratory mice. Eighteen female CBA/CaJ mice, socially housed or isolated, were tested to evaluate preference for signals produced by males. Social experience influenced female preference for male USV playback and soiled bedding. Female mice who had experience with males showed a stronger preference for olfactory signals, whereas female mice with experience only with other females preferred USV playback. Isolated mice showed a greater preference for signals of different modalities presented together than socially experienced mice. This preference may have occurred because of increased motivation to make social contact. The findings of this experiment illustrate that social experience could play a role in mate choice.

Build-up effect of auditory streaming in budgerigars (Melopsittacus undulatus)

When listening to a rapid tone sequence of the form ABA-ABA-ABA-… (where A and B are two tones of different frequencies and “-” indicates a silence interval), listeners may either hear one coherent “gallop” of three tones grouped together or two separate auditory streams (one high frequency, one low frequency) appearing to come from two sound sources. Research on humans indicates that the tendency to perceive two streams can be built up as exposure time increases. Neural recordings in European starlings show build-up effects of auditory streaming too. A lack of behavioral data on the build-up effect in nonhumans make it difficult to draw parallels between animals and humans. The present research aims to behaviorally validate the build-up effect of auditory streaming and factors that may influence the effect in nonhuman animals. Four budgerigars were tested in a categorization task using operant conditioning. “Streaming” categorization increased as the frequency separation increased. Additionally, in some ...