Representation of Auditory Motion Directions and Sound Source Locations in the Human Planum Temporale

Abstract

The ability to compute the location and direction of sounds is a crucial perceptual skill to efficiently interact with dynamic environments. How the human brain implements spatial hearing is, however, poorly understood. In our study, we used fMRI to characterize the brain activity of male and female humans 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). Using independently localized hPT, we show that this region contains information about auditory motion directions and, to a lesser extent, sound source locations. Moreover, hPT showed an axis of motion organization reminiscent of the functional organization of the middle-temporal cortex (hMTϩ/V5) for vision. 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. 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. Significance StatementCompared with what we know about visual motion, little is known about how the brain implements spatial hearing. Our study reveals that motion directions and sound source locations can be reliably decoded in the human planum temporale (hPT) and that they rely on partially shared pattern geometries. Our study, therefore, sheds important new light on how computing the location or direction of sounds is implemented in the human auditory cortex by showing that those two computations rely on partially shared neural codes. Furthermore, our results show that the neural representation of moving sounds in hPT follows a "preferred axis of motion" organization, reminiscent of the coding mechanisms typically observed in the occipital middle-temporal cortex (hMTϩ/V5) region for computing visual motion.

Visual motion processing recruits regions selective for auditory motion in early deaf individuals

“…Consistently with previous investigations (Fine et al, 2005;Finney et al, 2001;Sadato et al, 2005;Shiell et al, 2014), the present work confirms the recruitment of the superior temporal cortex in response to visual motion processing in early deaf individuals. Our study adds on these previous reports by showing that cross-modal visual motion processing is restricted to the portion of the right superior temporal cortex that is preferentially recruited by auditory motion in hearing individuals (Battal et al, 2019). Further, we observed that the visually reorganized STC of deaf people is capable of accurately discriminating between different categories of visual motion (i.e.…”

“…Although cross-modal activation of auditory regions has been observed in response to visual motion in deaf humans (Fine et al, 2005; Finney et al, 2001; Shiell et al, 2014), several important questions remain unanswered. In our study we tested whether visual motion processing recruits discrete regions of the temporal cortex known to selectively respond to specific auditory motion trajectories in hearing individuals (Battal et al, 2019; Hall and Moore, 2003; Warren et al, 2002). In addition, we used multivariate pattern decoding analyses to assess whether different motion trajectories could be discriminated in the deprived auditory cortex of deaf people.…”

Structural and functional network-level reorganization in the coding of auditory motion directions and sound source locations in the absence of vision

“…In the human auditory system, the planum temporale (hereafter hPT), which is located in the superior temporal cortex (posterior to Heschl’s gyrus), engages preferentially in the processing of moving sounds (Baumgart and Gaschler-Markefski, 1999; Warren, Zielinski and Green, 2002; Krumbholz et al ., 2005). Similar to what was found in hMT+/V5 for the processing of visual directions, hPT also codes for the direction of sounds following an axis-of-motion organization (Battal et al ., 2019).…”

Electrocorticography Evidence of Tactile Responses in Visual Cortices

“…According to one parcellation (Glasser et al 2016), electrode 2 was located on the border of the fundus of the superior temporal area FST and the putative human temporal area PHT. Interestingly, the latter was recently shown to code for auditory motion and source location (Battal et al 2019). Moreover, the electrode's visual pRF properties are in line with the localization of the electrode within TO2.…”

“…Even primary visual cortex has been shown to be involved in Braille reading by the visually impaired (Sadato et al 1996;Zangaladze et al 1999). Moreover, in the last decades several neuroimaging studies have reported auditory and tactile responses to motion stimuli in the human Middle Temporal complex hMT+, more specifically in the most anterior part of the complex, known as visual extrastriate area MST (Blake et al 2004;Van Boven et al 2005;Beauchamp et al 2007;Ricciardi et al 2007;Ptito et al 2009;Summers et al 2009;Sani et al 2010;Van Kemenade et al 2014) and also in the human planum temporale (Battal et al 2019). Other fMRI studies offer contradictory findings about the contribution of extrastriate cortex to tactile motion processing.…”