Discrimination training affects stimulus generalization in mice during Pavlovian eyeblink conditioning

TL;DR

This study shows that how mice are trained to distinguish between sounds affects how they generalize their learned eyeblink responses to new sounds.

Contribution

The study reveals that differential training increases generalization of eyelid responses based on stimulus differences.

Findings

Generalization of eyelid responses correlates with the difference between trained stimuli.

Generalization effects were observed in response probability and amplitude but not timing.

Differential training leads to more specific generalization compared to non-differential training.

Abstract

The delicate balance between discrimination and generalization of responses is crucial for survival in our ever-changing environment. In particular, it is important to understand how stimulus discrimination affects the level of stimulus generalization. For example, when we use non-differential training for Pavlovian eyeblink conditioning to investigate generalization of cerebellar-related eyelid motor responses, we find generalization effects on amount, amplitude and timing of the conditioned responses. However, it is unknown what the generalization effects are following differential training. We trained mice to close their eyelids to a 10 kHz tone with an air-puff as the reinforcing stimulus (CS+), while alternatingly exposing them to a tone frequency of either 4 kHz, 9 kHz or 9.5 kHz without the air-puff (CS−) during the training blocks. We tested the generalization effects during the expression of the responses after the training period with tones ranging from 2 kHz to 20 kHz. Our results show that the level of generalization tended to positively correlate with the difference between the CS+ and the CS− training stimuli. These effects of generalization were found for the probability, amplitude but not for the timing of the conditioned eyelid responses. These data indicate the specificity of the generalization effects following differential versus non-differential training, highlighting the relevance of discrimination learning for stimulus generalization.

Figures