Coding auditory space in the sighted and in the blind individuals

The ability to compute the location and direction of sounds is a crucial skill for efficiently interacting with dynamic environments in sighted people, and to a greater extent in congenitally blind people. How the auditory cortex implements spatial hearing is, however, poorly understood. In our study, we used fMRI to characterize the brain activity of sighted and congenitally blind people listening to sounds moving left, right, up, and down as well as static sounds. Whole-brain univariate results contrasting moving and static sounds varying in their location revealed a robust functional preference for auditory motion in bilateral human planum temporale (hPT) in the sighted and blind participants. Using independently localized hPT, we show that this region contains information about auditory motion directions and, to a lesser extent, sound source locations in both sighted and blind participants. Moreover, multivariate pattern analysis revealed that decoding accuracies in the blind participants were significantly lower in hPT when compared to the sighted participants. Importantly, whereas motion direction and location rely on partially shared pattern geometries in hPT, as demonstrated by successful cross-condition decoding, the responses elicited by static and moving sounds were, however, significantly distinct in both of the participant groups. Altogether, our results demonstrate that the hPT codes for auditory motion and location but that the underlying neural computation linked to motion processing is more reliable and partially distinct from the one supporting sound source location. Interestingly, intramodal plasticity in the auditory cortex may respect the functional organization of how the spatial hearing is encoded but leads to a decreased computational load in the congenitally blind individuals