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Functional connectivity of illusory surface representation in V1 with the default mode network

Poster No:

2551

Submission Type:

Abstract Submission

Authors:

Ana Arsenovic¹^,2, Natalia Zaretskaya¹^,2

Institutions:

¹University of Graz, Graz, Austria, ²BioTechMed-Graz, Graz, Austria

First Author:

Ana Arsenovic
University of Graz|BioTechMed-Graz
Graz, Austria|Graz, Austria

Co-Author:

Natalia Zaretskaya
University of Graz|BioTechMed-Graz
Graz, Austria|Graz, Austria

Introduction:

Illusory surface is represented in a topographic manner in the brain, with distinct patterns of surface enhancement and suppression of the surrounding regions across multiple early and higher-level visual topographic areas (Arsenovic et al., 2022; Kok & de Lange, 2014). Here we tested if the topographic representations of the illusory surface in the primary visual cortex (V1) are functionally connected to other, possibly also topographic areas in the brain.

Methods:

We present results from an fMRI study including 29 healthy participants. We measured BOLD responses while participants observed either illusory Kanizsa figures (diamond, left triangle or right triangle conditions) or inverted pac-man inducers (no illusion condition). Participants performed an unrelated detection task at the center of the visual field to ensure fixation. During the same session, we also acquired a functional localizer for each participant by presenting a flickering checkerboard at either surface, inducer, or background location of the illusory figure. We performed a seed-based functional connectivity (SBC) analysis, using the illusory surface and background representations in V1 as seeds. Changes in connectivity related to illusory surface presence were calculated as differences in functional connectivity between the illusory diamond condition and the no illusion condition, while accounting for the stimulus-evoked activity using a finite impulse response GLM analysis.

Results:

We observed a significant functional connectivity reduction of both the left and the right V1 seeds representing illusory surface with the lateral parietal default mode network (DMN LP) region of the right hemisphere during illusory shape presence. For the right V1 seed (representing illusory surface in the left hemifield), 191 voxels (90%) of the negative cluster (212 voxels, p_FDR = 0.001) with a peak at MNI [+42 -64 +28] overlapped with the DMN LP in the right hemisphere (Figure 1A). For the left V1 seed (representing illusory surface in the right hemifield), 118 voxels (91%) of the negative cluster (129 voxels, p_FDR = 0.023) with a peak at MNI [+44 -64 +30], overlapped the same DMN LP in the right hemisphere (Figure 1B). More specifically, the correlation between these two areas changed from being positive or zero in the inverted condition to being below zero in the illusory diamond condition (Figure 1, bar graphs). During illusory surface perception, activity in the surface representation of V1 and the DMN cluster thus fluctuated in opposite directions. We did not find significant changes in functional connectivity of the background subregion seed in V1 in either hemisphere.

Conclusions:

DMN can represent negative, but at the same time topographically specific visual responses (Szinte & Knapen, 2020). Our connectivity results point to the possible DMN involvement in illusory surface processing, with potentially overlapping topographic representation of the illusory surface with negative pRFs responding to visual stimulation. The latter hypothesis needs to be tested in future studies. Overall, our results add to the existing evidence for the DMN contribution to representing subjective aspects of perception (Gonzalez-Castillo & Bandettini, 2018; Lyu et al., 2022; Wilding et al., 2023).

Modeling and Analysis Methods:

Connectivity (eg. functional, effective, structural) ²

Perception, Attention and Motor Behavior:

Perception: Visual ¹

Keywords:

FUNCTIONAL MRI

Perception

Vision

Other - illusory surface; functional connectivity; V1; default mode network

^1|2Indicates the priority used for review

Provide references using author date format

Arsenovic, A. (2022). Dissociation between Attention-Dependent and Spatially Specific Illusory Shape Responses within the Topographic Areas of the Posterior Parietal Cortex. Journal of Neuroscience, 42(43), 8125–8135.
Gonzalez-Castillo, J. (2018). Task-based dynamic functional connectivity: Recent findings and open questions. NeuroImage, 180, 526–533.
Kok, P. (2014). Shape Perception Simultaneously Up- and Downregulates Neural Activity in the Primary Visual Cortex. Current Biology, 24(13), 1531–1535.
Lyu, D. (2022). Intrinsic brain dynamics in the Default Mode Network predict involuntary fluctuations of visual awareness. Nature Communications, 13(1), Article 1.
Szinte, M. (2020). Visual Organization of the Default Network. Cerebral Cortex, 30(6), 3518–3527.
Wilding, M. (2023). Resting-state neural correlates of visual Gestalt experience. Cerebral Cortex, bhad029.