Current Issue

Hakataya, S., Saito, Y., Katsu, N., Kamijo, M., Yuki, S., & Okanoya, K. (2026). Operant discrimination of emotional calls in rats: Are there biological constraints? Animal Behavior and Cognition, 13(3), 239-255.  https://doi.org/10.26451/abc.13.03.03.2026

Rats emit 50 kHz ultrasonic vocalizations (USVs) in positive contexts, while they produce 22 kHz USVs in negative contexts. 50 kHz USVs are possibly associated with positive affective states, while 22 kHz USVs with those of negative, and such associations may influence the feasibility of discrimination learning using USVs. Here, we investigated whether operant conditioning which utilizes USV stimuli is affected by presumed innate connections between 50 kHz USVs and positive, and 22 kHz USVs with negative affective states. We trained rats to discriminate 50 kHz and 22 kHz USVs in two conditions. In the congruent condition, 50 kHz USVs were paired with a positive event, while 22 kHz USVs with a negative one. In the incongruent condition, 22 kHz USVs were paired with a positive and 50 kHz USVs with a negative outcome. Rats were trained to serially reverse the learning conditions four times in total. Results show that the number of lever presses to reach the learning criteria did not significantly differ between the congruent and the incongruent conditions, both in the discrimination and reversal learning phases. These results suggest that rats did not learn the congruent condition faster than the incongruent condition, nor did the congruent condition more strongly hamper the acquisition of reversal learning than the incongruent condition. Namely, rats did not respond differently to the congruent and the incongruent conditions. The presumed innate connections (50 kHz USVs with positive, 22 kHz USVs with negative affective states) do not appear to substantially influence the feasibility of discrimination and serial reversal learning which utilizes USV stimuli.

Rats, Ultrasonic vocalization (USV), Operant conditioning, Biological predisposition