Effect of the duration of a conditioned stimulus on component recognition in binary taste mixtures in rats

• Published in: Journal of oral biosciences 2020-09, Vol.62 (3), p.267-271
• Main Authors: Yamamura, Tomoki, Nakamura, Fumihiko, Yasuo, Toshiaki, Suwabe, Takeshi, Sako, Noritaka
• Format: Article
• Language: English
• Subjects: Binary taste mixture; Conditioned taste aversion; Duration of conditioned stimulus; Lick test
• ISSN: 1349-0079
• DOI: 10.1016/j.job.2020.06.001

The aim of this behavioral study was to investigate the duration of a conditioned stimulus (CS-duration) necessary for rats to recognize the components of a binary taste mixture in a conditioned taste aversion (CTA) paradigm as well as the relationship between CS-duration and their spontaneous recovery. The experimental rats were categorized under conditioned and control groups and further divided into three groups according to the CS-duration: 10, 30, and 60 s. As the test stimuli, a mixture of 100 mM sucrose (S) + 30 μM quinine hydrochloride (Q) and its components were used. On day 1 of the CTA test, the number of licks (NL) for S + Q and S in all conditioned groups was significantly lower than that of the control group presented with CS for 60 s (CON-60), which was the representative control group determined by the initial CTA test. For Q, there was no significant difference between NL of the CTA group presented with CS for 10 s and that of CON-60; however, NL in the other two CTA groups, i.e., CTA-30 and CTA-60, was significantly lower than that of CON-60. When the rats were presented with a shorter CS-duration, they showed spontaneous recovery earlier depending on the CS-duration. These results suggest that rats can recognize a binary taste mixture and its components using a CS-duration of more than 30 s and that spontaneous recovery from CTA learning depends on the CS- duration. •Rats can acquire the CTA to a mixed taste solution by CS-duration during 10 s.•Rats can recognize the components of CS by CS-duration during 30 s.•Number of licks of unconditioned rats do not depends on CS-duration.•Shorter CS-duration brings about earlier spontaneous recovery.