Novel 31-kHz calls emitted by female Lewis rats during social isolation and social inequality conditions

Shota Okabe; Yuki Takayanagi; Masahide Yoshida; Tatsushi Onaka

doi:10.1016/j.isci.2023.106243

Novel 31-kHz calls emitted by female Lewis rats during social isolation and social inequality conditions

iScience. 2023 Feb 20;26(3):106243. doi: 10.1016/j.isci.2023.106243. eCollection 2023 Mar 17.

Authors

Shota Okabe¹, Yuki Takayanagi¹, Masahide Yoshida¹, Tatsushi Onaka¹

Affiliation

¹ Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan.

Abstract

Whether commonly used experimental animals show aversion toward inequality of social rewards, as humans do remains unknown. We examined whether rats emitted the 22-kHz distress calls under social reward inequality. Rats showed affiliative behavior for a specific human who repeatedly stroked and tickled them. When experimenter stroked another rat in front of them and during social isolation, these rats emitted novel calls with acoustic characteristics different from those of calls emitted under physical stress, namely air-puff. Under inequality conditions, rats emitted calls with higher frequency (∼31 kHz) and shorter duration (<0.5 s) than those emitted when receiving air-puff. However, with an affiliative human in front of them, the number of novel calls was lower and rats emitted 50-kHz calls, indicative of the appetitive state. These results indicate that rats distinguish between conditions of social reward inequality and the presence of an experimenter, and emit novel 31-kHz calls.

Keywords: Behavioral neuroscience; Biological sciences; Cognitive neuroscience; Neuroscience.