Brain-wide inputs to the non-lemniscal inferior colliculus in mice.

The inferior colliculus (IC) is the hub along the auditory pathway. Although it is fundamentally an auditory structure, the neurons in the IC, especially its non-lemniscal part also respond to multimodal stimuli. However, the sources of these non-auditory inputs are unclear. In this study, we injected the rAAV2-retro virus, a virus with efficient retrograde function, into the non-lemniscal IC of the Ai14 reporter line. The majority of cortical and subcortical brain areas, including cognitive, motor, somatosensory, auditory, and visual-related regions were revealed. The quantified whole brain input data have showed that the non-lemniscal IC received a higher proportion of inputs from ipsilateral cortical brain regions. The non-lemniscal IC integrates different multimodal patterns, for the dorsal cortex (ICD) receives primarily auditory inputs, and the external cortex (ICE) receives primarily auditory and somatosensory inputs. These findings demonstrate that auditory integration is shaped by a network of multi-sensory connections in the non-lemniscal IC subregions.