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

How does blindness affect the brain network supporting spatial hearing? We used a combined functional and diffusion MRI approach to study the impact of early blindness on the brain networks typically coding for audio–visual motion and location. Whole-brain functional univariate analysis revealed preferential response to auditory motion in a dorsal network including the planum temporale (hPT) as well as the anterior portion of the middle temporal cortex (hMT+/V5) in both sighted and congenitally blind participants (male and female). Blind participants showed additional preferential response to auditory motion in the posterior region of hMT+/V5. Importantly, multivariate decoding analysis revealed the presence of motion direction information that was higher in hMT+/V5 and lower in hPT of blind relative to sighted people. Decoding sound source location showed a similar pattern of results even if the decoding accuracies were in general lower than those obtained from motion directions. Diffusion MRI revealed that the macrostructure (trajectory and connectivity index) of hMT+/V5 — hPT connectivity did not differ between groups, while the microstructure of the connections was altered in blind people. These results suggest that early visual deprivation triggers a network-level reorganization that enhances the recruitment of occipital areas in conjunction with a release in the computational workload of temporal regions typically dedicated to spatial hearing. This functional reorganization is accompanied by white-matter microstructural alterations in related occipital-temporal connections.

Unsettled Issues Regarding Visual Communication Between Automated Vehicles and Other Road Users

As automated road vehicles begin their deployment into public traffic, and they will need to interact with human driven vehicles, pedestrians, bicyclists, etc. This requires some form of communication between those automated vehicles (AVs) and other road users. Some of these communication modes (e.g., auditory, motion) were discussed in “Unsettled Issues Regarding Communication of Automated Vehicles with Other Road Users.” Unsettled Issues Regarding Visual Communication Between Automated Vehicles and Other Road Users focuses on sisual communication and its balance of reach, clarity, and intuitiveness. This report discusses the different modes of visual communication (such a simple lights and rich text) and how they can be used for communication between AVs and other road users. A particular emphasis is put on standardization to highlight how uniformity and mass adoption increases efficacy of communications means.

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

In early deaf individuals, the auditory deprived temporal brain regions become engaged in visual processing. In our study we tested further the hypothesis that intrinsic functional specialization guides the expression of cross-modal responses in the deprived auditory cortex. We used functional MRI to characterize the brain response to horizontal, radial and stochastic visual motion in early deaf and hearing individuals matched for the use of oral or sign language. Visual motion showed enhanced response in the ‘deaf’ mid-lateral planum temporale, a region selective to auditory motion as demonstrated by a separate auditory motion localizer in hearing people. Moreover, multivariate pattern analysis revealed that this reorganized temporal region showed enhanced decoding of motion categories in the deaf group, while visual motion-selective region hMT+/V5 showed reduced decoding when compared to hearing people. Dynamic Causal Modelling revealed that the ‘deaf’ motion-selective temporal region shows a specific increase of its functional interactions with hMT+/V5 and is now part of a large-scale visual motion selective network. In addition, we observed preferential responses to radial, compared to horizontal, visual motion in the ‘deaf’ right superior temporal cortex region that also show preferential response to approaching/receding sounds in the hearing brain. Overall, our results suggest that the early experience of auditory deprivation interacts with intrinsic constraints and triggers a large-scale reallocation of computational load between auditory and visual brain regions that typically support the multisensory processing of motion information.HighlightsAuditory motion-sensitive regions respond to visual motion in the deafReorganized auditory cortex can discriminate between visual motion trajectoriesPart of the deaf auditory cortex shows preference for in-depth visual motionDeafness might lead to computational reallocation between auditory/visual regions.

Direct structural connections between auditory and visual motion selective regions in humans

ABSTRACTIn humans, the occipital middle-temporal region (hMT+/V5) specializes in the processing of visual motion, while the Planum Temporale (hPT) specializes in auditory motion processing. It has been hypothesized that these regions might communicate directly to achieve fast and optimal exchange of multisensory motion information. In this study, we investigated for the first time in humans the existence of direct white matter connections between visual and auditory motion-selective regions using a combined functional- and diffusion-MRI approach. We found reliable evidence supporting the existence of direct white matter connections between individually and functionally defined hMT+/V5 and hPT. We show that projections between hMT+/V5 and hPT do not overlap with large white matter bundles such as the Inferior Longitudinal Fasciculus (ILF) nor the Inferior Frontal Occipital Fasciculus (IFOF). Moreover, we did not find evidence for the existence of reciprocal projections between the face fusiform area and hPT, supporting the functional specificity of hMT+/V5 – hPT connections. Finally, evidence supporting the existence of hMT+/V5 – hPT connections was corroborated in a large sample of participants (n=114) from the human connectome project. Altogether, this study provides first evidence supporting the existence of direct occipito-temporal projections between hMT+/V5 and hPT which may support the exchange of motion information between functionally specialized auditory and visual regions and that we propose to name the middle (or motion) occipito-temporal track (MOTT).