Primary visual cortex BOLD responses to relative localization of sounds at 7T

To clarify the computational role and dynamics of auditory-driven cross-modal activations in visual cortices, we investigated the recruitment of the primary visual cortex (V1) during auditory spatial perception using fMRI and dynamic causal modeling (DCM). Ten participants estimated the relative position of sounds with respect to two spatial landmarks. We found significant activation of V1 in response to the sound to localize, along with bilateral activation in the primary auditory cortex (A1) and intraparietal sulcus (IPS; pFWE < 0.001). Moreover, we observed task-dependent changes in the effective connectivity between V1, A1, and IPS: in particular, the coupling between A1 to IPS, as well as from IPS to V1 increased positively. This study suggests that judgments of the relative distance between sounds elicit activity in V1, and V1 recruitment is likely explained by an increased effective connectivity from IPS. This network may support the brain ability to perform high-level spatial computations in the auditory domain.