Locating the source of a specific sound in a complex environment and determining its saliency is critical for survival. The superior colliculus (SC), a sensorimotor midbrain structure, plays an important role in sound localization and has been shown to have a topographic map of the auditory space in a range of species. In mice, previous studies using broadband white noise stimuli found that high-frequency monaural spectral cues and interaural level differences (ILDs) are used to generate a neuron's spatially restricted receptive field (RF), and that these RFs are organized topographically along the azimuth. However, in a naturalistic environment, the auditory stimuli that an animal encounters may have restricted spectral components, although these sound sources can still be localized efficiently. It remains unknown whether and how the SC neurons respond to frequency restricted sounds and in turn, how this changes the organization of their RFs into a topographic map. Here, we show results from large-scale in vivo physiological recordings of SC neurons from male and female mice in response to white noise, naturalistic ultrasonic pup call and chirps. We find that mouse SC auditory neurons respond to a pup call and chirps with distinct temporal patterns and a spatial preference predominantly at ∼60 degrees in contralateral azimuth. In addition, we categorized auditory SC neurons based on their spectrotemporal receptive field (STRF) patterns and demonstrated that there are at least 4 classes of auditory responsive neurons in the SC that lie in different locations along the anterior-posterior axis of the SC.Significance Statement The superior colliculus (SC) receives topographically organized visual and auditory inputs used for object localization. While visually responsive SC neurons are well studied, less is known about auditory neurons. We presented white noise, pup call and chirp stimuli to mice while recording from SC neurons. Analysis of the responses defines distinct classes of auditory neurons. Interestingly, while auditory neurons respond to pup calls, the responses are not organized topographically. Despite this, the population response to a pup call predicts the location of a stimulus, albeit not as well as the that generated from white noise. These results show that the SC may use different strategies to localize sound depending on the spectral composition of the source.
Si et al. (Fri,) studied this question.