AUDIOVISUAL RESPONSE PROPERTIES OF VISUAL-CORTEX PROJECTING NEURONS IN THE AUDITORY CORTEX

Cells in the primary visual cortex (V1) not only respond to visual stimulation, but are also modulated by sound. While part of the auditory evoked modulation in V1 can be explained by motor behaviour of the animal, another part was found to be best explained by auditory variables. Previous studies suggested that this auditory modulation of V1 likely originates from the auditory cortex (AC). Yet, the circuit-level functional architecture of the AC→V1 remains poorly understood. To address this, we performed acute, in vivo recordings in the AC of the mouse using high-density silicon probes (Fig. 1A), while specifically identifying AC→V1 projecting neurons by optogenetic tagging (Fig. 1C, D). We investigated the response characteristics of AC→V1 projecting neurons in response to auditory, visual and audiovisual stimulation (Fig. 1B), while controlling for the effects of motor movement. Interestingly, compared to non-tagged neurons in the AC, AC→V1 projecting neurons were more likely to be auditory, visual and multisensory responsive. Part of the AC→V1 projecting neurons responded to specific orientations and/or frequencies of the visual and auditory stimuli, respectively. These feature-specific characteristics were not different from non-tagged neurons. These results show that, rather than just being a source of gain modulation, AC→V1 projecting neurons carry a dense stream of auditory and visual information to V1.

Fig 1. Identification of V1-projecting cells in the AC and general experimental setup.