Active and passive listening channels for auditory scene analysis

Angeles Salles

Animals exploit acoustic signals for a wide range of behaviors, from sound communication to predator localization. Echolocating bats, for example, rely not only on sound to navigate the environment, but also to communicate with conspecifics. Past research has yielded a wealth of data on the neural mechanisms of biological sonar in bats, but far less is known about how the bat auditory system differentiates between signals used for echolocation and acoustic communication. My research aims to address this question by recording and analyzing inferior colliculus responses to sound stimuli that carry echo information from the environment and social acoustic information from conspecifics. Experiment 1 will compare neural activity in bats listening to playbacks of their own echolocation signals, those of conspecifics, and acoustic communication signals. Experiment 2 will investigate the dynamics of neural activity evoked by actively echolocating bats engaged in a target-tracking task. Experiment 3 will exploit novel methods to characterize auditory activity evoked by sonar echoes and social communication signals in the free-flying bat. Comparative studies are key to identifying specializations and general principles of neural systems, and this project will contribute to a broader understanding of auditory processing in animals that rely on sound to guide behavior.

Figure 1.
Graphical abstract of experimental design proposed for the project.

Experiment I. Inferior colliculus neural responses of restrained bats passively listening to playbacks of different calls.

Experiment II: Inferior colliculus neural responses of vocalizing animals to sonar echoes from real-time echoes from calls, self-playbacks and conspecific playbacks.

Experiment III: Inferior colliculus neural recordings of freely flying bats. Quantitative analyses of behavior will include echolocation and social call features, sonar beam aim, 3D flight trajectory, flight configuration of bat pairs, and prey capture success.

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