The auditory midbrain mediates tactile vibration sensing

Vibrations are ubiquitous in nature, shaping behavior across the animal kingdom. For mammals, sound waves traveling through air are captured by the cochlea and the neural signals they generate are encoded in the auditory system. Mechanical vibrations acting on the body are detected by mechanoreceptors of the skin and deep tissue and processed by the somatosensory system. As such, the neural pathways that underlie perception and reaction to sound waves and mechanical vibrations are believed to be anatomically distinct and functionally independent. Here, we report that mechanical vibrations are prominently encoded by neurons in the lateral cortex of the inferior colliculus (LCIC) of the auditory midbrain. LCIC responses to environmental vibrations are mediated by Aβ rapidly adapting (RA)-LTMRs associated with Pacinian corpuscles, which are exquisitely sensitive and unique in their ability to entrain to high frequency (40-1000 Hz) environmental vibrations. Remarkably, most LCIC neurons are dual somatosensory and auditory environmental vibration detectors. Moreover, the LCIC is required for behavioral responses to high frequency mechanical vibrations, but not other somatosensory modalities. Thus, environmental vibrations captured by Pacinian corpuscles of the body are encoded in the auditory midbrain to mediate behavior.