Talk Session: Monday, May 20, 2024, 10:45 am – 12:15 pm, Talk Room 2

Talk 1, 10:45 am

Increased use of priors in the oblique effect in children

Sarit Szpiro1,2, Eman Mhajne1; 1University of Haifa, 2The Edmond J. Safra Brain Research Center, University of Haifa

Background: According to Bayesian inference models of vision, perception is affected by incoming input (i.e., likelihood) and by past experiences (i.e., priors). Although perceptual inference has been widely studied in adults, much less is known about how Bayesian inference is modified during development. Here, we study how priors impact perception during development by examining the oblique effect in children. In the oblique effect, adults exhibit lower motion direction thresholds and larger estimation biases for cardinals versus oblique motion directions. Methods: We compared the perception of motion directions using RDK motion stimuli in adults (ages 20-38) and children (ages 7-9). First, we determined individual coherence discrimination thresholds for near oblique and for near horizontal directions using a staircase procedure. Then, participants were presented their at-threshold motion directions (near horizontal/oblique) and moved a mouse to estimate directions. Results: Results indicated that children exhibited higher overall thresholds compared to adults. Both groups showed significantly lower thresholds for horizontal motion compared to oblique motion, with this difference significantly more pronounced in children. Additionally, both groups displayed significantly larger estimation biases for near horizontal directions, which again was significantly more prominent in children. Conclusions: Even though horizontal and oblique stimuli were presented at their corresponding thresholds, there were larger estimation biases for horizontal versus oblique in both groups. This suggests that these biases persist even when equating for difficulty, an important factor to consider in future computational models of bias and discriminability. Importantly, our results reveal that children exhibit larger oblique effects than adults. The overall worse thresholds in children (i.e, likelihood) may drive children to rely more on perceptual priors than adults, impacting their perception of motion. Our study contributes valuable insights into the developmental aspects of perceptual inference and the role of priors in perception during development.

Acknowledgements: ISF research grant 1198/22 to Sarit Szpiro

Talk 2, 11:00 am

The emergence of VWFA laterality: examining the role of white matter connectivity in early childhood

Jin Li1,2 (), Leah DiRubio1,2, Zeynep Saygin1,2; 1Department of Psychology, The Ohio State University, 2Center for Cognitive and Behavioral Brain Imaging (CCBBI), The Ohio State University

The visual word form area is a brain region that selectively responds to visual words as people become literate. Interestingly, while face selectivity is typically dominant on the right hemisphere, word selectivity is dominant on the left. What factors contribute to the development of left laterality for words? Here we tested three potential sources of this word laterality: 1) the development of face laterality, 2) cross-hemispheric structural connectivity, and 3) connectivity with ipsilateral language regions. We scanned children (3-9 years, prereaders and readers) and adults on an fMRI task to extract functional activation to words and faces and diffusion-weighted imaging (DWI) in the same participants to examine white matter connectivity. In children, even though word selectivity became increasingly left-lateralized and face selectivity more right-lateralized over development, they were not directly related: while face laterality increased with age in both readers and prereaders, word laterality increased with age only in readers. Word laterality additionally showed a significant correlation with cross-hemispheric connectivity between left VWFA and its right homotope, especially in readers. Furthermore, we found that in readers, the connectivity of VWFA with ipsilateral frontal language regions was positively related to its laterality. Interestingly, in adults, neither face laterality nor connectivity was correlated with individual differences in word laterality. These results demonstrate how anatomical and developmental factors contribute to changes in laterality of high-level visual cortex, and highlight the role of both cross-hemispheric and ipsilateral white matter connectivity in developing word laterality.

Acknowledgements: Alfred P. Sloan Research Fellowship (to Z.M.S); CCBBI Gibson Research Award (to J.L.)

Talk 3, 11:15 am

Early neural development of social perception: evidence from voxel-wise encoding in young children and adults

Elizabeth Jiwon Im1 (), Angira Shirahatti1, Leyla Isik1; 1Johns Hopkins University

From a young age, children show advanced social perceptual and reasoning abilities. However, the neural development of these abilities is still poorly understood. To address this gap, we used publicly available fMRI data collected while children and adults watched an engaging and socially rich movie to investigate how the cortical basis of social processing changes throughout development. We annotated segments of the movie with visual and social features, including motion energy, presence of faces, presence of a social interaction, theory of mind (ToM) events, valence and arousal. Using a voxel-wise encoding model trained using these features, we find that visual (motion energy) and social (faces, social interaction, ToM, valence, and arousal) features can both predict brain activity in children as young as three years old across the cortex, with particularly high predictivity in motion selective MT and the superior temporal sulcus (STS). Furthermore, individual social feature models showed that while representations for some social features, like ToM, develop throughout childhood, social interaction representations in the STS appear adult-like in even the youngest children. The current study, for the first time, links neural activity in children to specific social features during naturalistic movie viewing and suggests social interaction perception is supported by early developing neural responses in the STS.

Acknowledgements: This work was supported with funds from the Clare Boothe Luce Program for Women in STEM and NIMH R01MH132826 awarded to LI. We would like to thank Hillary Richardson and colleagues for data used in this study.

Talk 4, 11:30 am

High-resolution diffusion MRI of the cortico-cortical connections between lower visual areas reveals divergence of connections and enhanced connectivity of the central visual field representation

Ziqi Hao1 (), Alex Valcourt Caron2, Janine Mendola1, Maxime Descoteaux2, Amir Shmuel1; 1McGill University, Montreal, QC, Canada, 2Universite de Sherbrooke, Sherbrooke, QC, Canada 

Studies of the dense structural connections between human lower visual areas with diffusion MRI (dMRI) are sparse. To investigate this fine connectivity, a dMRI pulse sequence is required to operate at both high-resolution and high signal-to-noise ratio (SNR). gSldier-SMS (Setsompop et al., 2018) makes acquiring diffusion MRI data with high SNR and high resolution possible. Using gSlider-SMS, we aim to image the white matter connections between the densely connected lower visual areas V1, V2, and V3. Data were obtained from 10 healthy subjects. Using gSlider-SMS, we acquired dMRI with isotropic 1 mm voxels. We used Benson’s atlas (Benson & Winawer, 2018) to generate the retinotopic polar angle and eccentricity maps of human visual areas V1, V2, and V3. Our diffusion data demonstrated a retinotopically organized connectivity pattern between V1-V2, V2-V3, and V1-V3. Moreover, our results also revealed differential density in connectivity patterns between the central and peripheral visual fields. We found that for each pair of connections between V1, V2, and V3, the central visual field regions were more densely connected than the regions in the periphery. This underscores the notion that the central visual field, responsible for detailed and sharp vision, might have evolved to have stronger connectivity to facilitate visual processing at high acuity. In addition, we evaluated the divergence of connections emerging from an eccentricity range in one visual area and connecting to a second visual area. A Gaussian curve showed a good fit to the divergence distribution. Our study provides novel insight into the visual cortex's intricate connectivity patterns, underlining the importance of central visual field representation, retinotopic organization, and hierarchical processing. Our findings also pave the way for investigating the structural-functional relationship of connections between lower visual areas, potentially leading to a deeper understanding of vision-related disorders.

Acknowledgements: This work was supported by the Assistant Secretary of Defense for Health Affairs endorsed by the Department of Defense, through the Vision Research Program (VRP) under Award No W81XWH1910853. Opinions, interpretations, conclusions and recommendations of the author are not endorsed by the Department.

Talk 5, 11:45 am

Reduced Dissociation between Perception and Action in Individuals with Autism

Zoha Ahmad1 (), Orly Aziza1, Tzvi Ganel2, Bat-Sheva Hadad3, Erez Freud1; 1York University, 2Ben Gurion University of the Negev, 3University of Haifa

Changes in perceptual behaviors are commonly reported in individuals with Autism. Nevertheless, the mechanisms that mediate these alterations are yet to be determined. One hypothesis is that these changes are the result of reduced cortical specialization. In this study, we scrutinize this hypothesis utilizing the framework of the functional dissociation between perception and action. Past studies have demonstrated that unlike their robust effect on perception, altering the temporal or spatial size context of stimulus presentation have little effect on grasping. Therefore, we manipulated the temporal or spatial context of stimulus presentation, while both autistic and neurotypical participants completed grasping and estimation tasks. In Experiment 1 (spatial context), we used two objects that differ in size, and placed on an illusory Ponzo background such that they were perceived as “close” or “far” from the observer. The neurotypical individuals showed a perception-action dissociation with a robust effect of the illusion only during the estimation task, and no effect of the illusion during grasping. In contrast, autistic individuals were affected by the illusion under both conditions. In Experiment 2 (temporal context), we presented a standard stimulus (40mm) in two temporally distinct blocks. In one block (“wide”), the stimuli used as flanks for the standard stimuli encompassed a larger range (20-60mm). In the other block (“narrow”), the flanks encompassed a smaller range (35-45mm). The neurotypical individuals showed a perception-action dissociation with a robust effect of the experimental temporal context only during the perceptual task. In contrast, autistic individuals showed a consistent effect of the experimental temporal context under the perceptual and the visuomotor task, with larger JNDs for the standard stimulus presented during the “wide” block. Taken together, these results provide converging evidence for reduced functional dissociation between perception and action in autism, such that perceptual representations intrude and modulate visuomotor behaviors.

Talk 6, 12:00 pm

Visual experience is required to develop a flexible sense of position.

Carolina Tammurello1,2 (), Lara Coelho1, Maria Bianca Amadeo1, Claudio Campus1, Walter Setti1, Monica Gori1; 1Italian Institute of Technology, 2University of Genoa

In the somatic Rubber Hand Illusion, a blindfolded participant is guided in brushing a dummy hand, while the experimenter synchronously brushes the participant’s hand. This can induce proprioceptive drift (PD), i.e., a shift in perceived position of one’s own hand. One population that is immune to PD are blind adults, a fact often attributed to their hypothesized superior proprioceptive precision. To explore the role of visual experience on PD and if a lack of vision causes different developmental trajectories, we recruited Severely Visually Impaired (SVI) children (6-11 y.o.; n=14) and compared their PD to that of sighted-age-matched controls (n=51). As hypothesized, SVI children failed to show PD across the age span, unlike sighted children, whose PD increased as a function of age. We then tested whether I) proprioceptive precision and II) distance between the initially perceived position of their own hand and the placement of the dummy hand predicted PD in sighted children. I) did not predict PD in sighted children, nor were there any differences between groups in this parameter. Instead, II) was significant (i.e., the farther the two, the larger the shift) and not modulated by age. We speculate that sighted children show PD as a reaction to the conflict between inter-hand distance (proprioceptive information) and coherence between the stimulation performed (which is actually on the dummy hand) and the one received (tactile and kinesthetic feedbacks). Thus, an intermediate position, where the stimulated hand would be if participants were stroking their own hand, becomes an attractor. The perceptual system of SVI children, instead, fails to react to this conflict and continues to compute the position of the hand irrespectively of any additional contextual information. Visual experience is therefore necessary to remap the body in external space and achieve a reduction in intersensory conflict.

Acknowledgements: The research was supported by the MYSpace project (PI Monica Gori), which has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 948349)