Pupillary Dilation Response to Changes in Sound Stimuli

(In-Person) Oral Panel—Stimuli and Response, Poster Presentation

To understand the world around us, the auditory system of our brains discriminates between different sounds to interpret our surroundings. Normally, simple sounds (like pure tones) are used to study the neural mechanisms for processing sounds by training animals. Training animals to discriminate between sounds is an arduous endeavor. Further, using simple sounds limits our understanding of how the brain interprets sounds of the complexity that is experienced every day. To address these problems, we developed a methodology to study sound discrimination in naive mice without training the animals by using pupillometry.

Changes in pupil size is one of the many responses to stimuli an animal can have. A study performed by Montes-Lourido et al. found pupil diameter changes correlate with an increase in motivation, effort and arousal in the brain in subjects (Montes-Lourido et al., 2021). Previous studies found changes in pupil sizes to sounds like pure tones and animal calls (Montes-Lourido et al., 2021). We hypothesized pupil responses would occur when the animal is presented with complex sounds that are found in nature. To study natural complex sounds, we first had to establish if pupillary dilation responses occurred to changes in simpler sounds like chords. We found that the pupils exhibited a pupillary dilation response to changes in frequency. Through this project, we determined pupillary dilation responses can be used as a method to study frequency discrimination in mice.