Summary: New research in mice shows that the inferior colliculus processes movement and sound at the same time, and that movement-related signals can reshape how external sounds are represented.
Source: eLife
New research provides clearer insight into how the brain integrates auditory and motor information.
Researchers publishing in the open-access journal eLife report that a midbrain structure long regarded primarily as an auditory hub — the inferior colliculus (IC) — simultaneously processes signals related to both sound and movement. The study, conducted in mice, also reveals mechanisms that could help animals avoid confusing self-generated noise with important environmental sounds while they are moving.
The IC is a central node in the auditory pathway where nearly all ascending sound information converges. For decades it has been studied for its role in analyzing sound timing, frequency and location — functions critical to detecting and responding to threats or opportunities in the environment. However, relatively little was known about how IC neurons behave while animals are actively moving, a routine condition in natural hearing situations.
Lead author Yoonsun Yang of the Center for Neuroscience Imaging Research (CNIR) at the Institute for Basic Science in Suwon, Korea, explains the motivation behind the work: animals must be able to separate noises they themselves produce from sounds coming from the environment. Prior evidence that auditory neurons below the cerebral cortex change their activity during different motor behaviors prompted the team to ask whether IC cells carry movement-related signals as well as auditory signals.
To investigate, the researchers recorded neuronal activity in the IC of mice walking on a treadmill. They observed that many IC neurons showed clear modulation linked to locomotion: some cells increased their firing rate when the animal moved, while others decreased it. Importantly, these changes often occurred not only during walking but also just before movement began, suggesting that the IC receives internal motor-related signals in addition to external auditory input.
To make sure these effects were not simply driven by sounds generated by the animals’ own footsteps or treadmill noise, the team repeated the experiments in deaf mice. The same pattern of locomotion-related modulation appeared even in the absence of auditory input, confirming that the IC receives non-auditory signals related to movement.
Next, the researchers presented external sounds to normally hearing mice while they walked. They found that sound-evoked responses in the IC were generally suppressed during locomotion. This suppression reduced the overall responsiveness to external acoustic stimuli, yet it sharpened frequency selectivity across the neuronal population without shifting each neuron’s preferred frequency. In other words, while movement dampened responses to incoming sounds, neurons preserved the specific frequencies to which they were tuned and became more selective.
Senior author Gunsoo Kim, who leads the Auditory Processing Laboratory at CNIR, notes that these dual effects—modulation by movement and concurrent suppression of sound-evoked responses—could serve complementary functions. Movement-linked activity could allow the IC to track or predict locomotor state, while attenuation of response to external sounds during movement may help prevent self-generated noises from masking important environmental cues such as predator sounds or communication signals.
Collectively, the results highlight a previously underappreciated role for the inferior colliculus: it integrates locomotion-related and auditory information to support accurate and rapid sensory processing during behavior. This integration likely helps animals adapt their perception and actions in real time when they are moving, enhancing survival in complex acoustic environments.
Source:
eLife
Media Contacts:
Emily Packer – eLife
Image Source:
The image is in the public domain.
Original Research: Open access
“Integration of locomotion and auditory signals in the mouse inferior colliculus.” Authors: Yoonsun Yang, Joonyeol Lee, Gunsoo Kim. eLife. doi: 10.7554/eLife.52228
Abstract
Integration of locomotion and auditory signals in the mouse inferior colliculus
The inferior colliculus (IC) is the major midbrain auditory integration center, where virtually all ascending auditory inputs converge. Although the IC has been extensively studied for sound processing, little is known about the neural activity of the IC in moving subjects, as frequently happens in natural hearing conditions. Here, by recording neural activity in walking mice, the authors show that the activity of IC neurons is strongly modulated by locomotion, even in the absence of sound stimuli. Similar modulation was also found in hearing-impaired mice, demonstrating that IC neurons receive non-auditory, locomotion-related neural signals. Sound-evoked activity was attenuated during locomotion, and this attenuation increased frequency selectivity across the neuronal population while maintaining preferred frequencies. These results suggest that during behavior, integrating movement-related and auditory information is an essential aspect of sound processing in the IC.