Recognition of Modified Conditioning Sounds by Competitively Trained Guinea Pigs.

Hisayuki Ojima,Junsei Horikawa

doi:10.3389/fnbeh.2015.00373

Abstract

The guinea pig (GP) is an often-used species in hearing research. However, behavioral studies are rare, especially in the context of sound recognition, because of difficulties in training these animals. We examined sound recognition in a social competitive setting in order to examine whether this setting could be used as an easy model. Two starved GPs were placed in the same training arena and compelled to compete for food after hearing a conditioning sound (CS), which was a repeat of almost identical sound segments. Through a 2-week intensive training, animals were trained to demonstrate a set of distinct behaviors solely to the CS. Then, each of them was subjected to generalization tests for recognition of sounds that had been modified from the CS in spectral, fine temporal and tempo (i.e., intersegment interval, ISI) dimensions. Results showed that they discriminated between the CS and band-rejected test sounds but had no preference for a particular frequency range for the recognition. In contrast, sounds modified in the fine temporal domain were largely perceived to be in the same category as the CS, except for the test sound generated by fully reversing the CS in time. Animals also discriminated sounds played at different tempos. Test sounds with ISIs shorter than that of the multi-segment CS were discriminated from the CS, while test sounds with ISIs longer than that of the CS segments were not. For the shorter ISIs, most animals initiated apparently positive food-access behavior as they did in response to the CS, but discontinued it during the sound-on period probably because of later recognition of tempo. Interestingly, the population range and mean of the delay time before animals initiated the food-access behavior were very similar among different ISI test sounds. This study, for the first time, demonstrates a wide aspect of sound discrimination abilities of the GP and will provide a way to examine tempo perception mechanisms using this animal species.

Highlights

In the early training stage, paired guinea pig (GP) competed for food with the conflict behavior shown above and initiated distinct food-approaching behaviors including quick head swaying combined with neck extending above the food saucer and/or circling about it (i.e., behavioral reactions (BhRs); see the 1st scene of Video 2) at the onset of the T sound
If the minimum Reaction time (RT) to the conditioning sound (CS) reflects the temporal integration time window (TITW) for processing and coding of timing information, it is possible to comprehensively explain the behavioral variability to the test sounds different in tempo
Findings from the tempo discrimination test suggest that the GP may have an inherent, asymmetrical disposition in tempo perception, implying that faster tempos of natural sounds might be more meaningful for the survival or social behavior of this species, such as approaching sounds produced by predators in their final stage of attack

Summary

Introduction

A considerable number of studies have used the guinea pig (Cavia porcellus; GP) as an animal model to study cochlear functions (Prosen et al, 1981; Miller, 2001; Pfingst et al, 2011; Géléoc and Holt, 2014), mechanisms of acoustic trauma (Nicol et al, 1992; Noreña et al, 2010), and Competitively-Trained Guinea Pig’s Sound Recognition learning-induced plasticity of adult auditory cortex (Bakin and Weinberger, 1990; Edeline and Weinberger, 1993; Edeline et al, 1993; Weinberger et al, 1993). This may have led to hesitation of use of the GP in research of the sound discrimination abilities that have been investigated for rats and mice

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