Shared Representation of Visual and Auditory Motion Directions in the Human Middle-Temporal Cortex

Abstract

Highlights d Cross-modal decoding of visual and auditory motion directions in hMT + /V5 d Motion-direction representation is, however, not abstracted from the sensory input d We reveal a multifaced representation of multisensory motion signals in hMT + /V5

Are critical periods reversible in the adult brain? Insights on cortical specializations based on sensory deprivation studies

“…Over the years, similar results were reported by several additional studies documenting in congenitally blind adults, maintained specializations for other computations typically processed in the dorsal "visual" stream -also previously conceived as strictly visual. This was the case of spatial localization in the Middle Occipital Gyrus (MOG) and motion detection in the MT + complex, experienced via both audition or touch (Bedny et al, 2010;Collignon et al, 2011;Dormal et al, 2016;Jiang et al, 2014;Matteau et al, 2010;Poirier et al, 2006;Renier et al, 2010;Ricciardi et al, 2007;Strnad et al, 2013;Wolbers et al, 2011) (see also (Hagen et al, 2002;Rezk et al, 2020) for convergent results in sighted adults) ( Fig. 1).…”

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

“…Interestingly, however, the ‘deaf’ A-motion-STC was found to exert a stronger excitatory influence over motion-selective activity in hMT+/V5 compared to its reciprocal from hMT+/V5. A tentative interpretation of this observation might relate to the intrinsic multifaceted representation of motion signals in hMT+/V5 (Rezk et al, 2020) and its potential role as a higher-level hub for motion processing, which might result into higher sensitivity of this region to motion information conveyed by auditory and visual motion-sensitive regions. More specifically, predetermined excitatory afferent connections from A-motion-STC to hMT+/V5 might exceed in quantity and excitatory strength their reciprocal from hMT+/V5 and represent a privileged target for cross-modal recycling of long-range connectivity following early auditory deprivation.…”

“…Our observation also suggests a prominent lateralization of the reorganization process for moving stimuli in the right hemisphere of deaf individuals, consistent with the well-known right lateralization of visuo-spatial processing (Corbetta and Shulman, 2002) and the observation that cortical thickness of the right planum temporale is greater in deaf individuals with better visual motion detection thresholds (Shiell et al, 2016). Furthermore, the enhanced multivoxel decoding accuracy, detected in the reorganized right planum temporale of deaf people suggests that this region might be capable of representing discrete motion trajectories, a feature that is typically found in occipital region selective for visual motion like hMT+/V5 (Kamitani and Tong, 2006; Rezk et al, 2020).…”

“…Notably, increased functional connectivity between the hMT+/V5 and the STC during auditory motion has been recently reported in early blind compared to sighted individuals (Dormal et al, 2016), supporting the hypothesis that intrinsic occipito-temporal connections underlying audio-visual integration may play a prominent role in driving the functionally selective cross-modal reorganization observed in case of auditory or visual deprivation (Benetti et al, 2017; Hannagan et al, 2015; Mattioni et al, 2020). Indeed, since motion processing engages both vision and audition, it can be hypothesized that a privileged and intrinsic link already exists between auditory and visual motion selective regions in hearing people (Gurtubay-Antolin et al, 2020; Poirier et al, 2005; Rezk et al, 2020), leading to the emergence of selective cross-modal recruitment in the auditory cortex of early deaf individuals (Dormal and Collignon, 2011; Lomber et al, 2010; Ricciardi et al, 2014). Recently, we also supported this hypothesis in deaf humans by showing that face-selective cross-modal recruitment of the ‘deaf’ temporal voice area, and the large-scale functional reorganization within the face-voice systems, are associated with overall preserved macrostructural connections between visual face- and auditory voice-sensitive brain regions (Benetti et al, 2018).…”

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

“…Recent works have suggested that hMT+/V5 and hPT are part of a network involved in the processing and integration of audio-visual motion information(Gurtubay-Antolin et al ., 2021). For instance, in addition to its well-documented role for visual motion, hMT+/V5 also responds preferentially to auditory motion (Poirier et al ., 2005) and contains information about planes of auditory motion using a similar representational format in vision and audition (Rezk et al ., 2020).…”