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Finzi, D.

Publications and source records attributed to Finzi, D..

9 recordsLinked to original sources

From adolescence to adulthood: functional fingerprints of high-level visual cortex reveal differential development of visuospatial processing

Reading, social interaction, and navigation rely on visuospatial computations by population receptive fields (pRFs) in category-selective regions of the ventral, lateral, and dorsal streams. However, how visuospatial computations vary across streams and category, or develop during adolescence is unknown. Using functional magnetic resonance imaging (fMRI) and pRF modeling in adolescents and adults, we investigate the development of pRFs and category-selectivity. Adolescents and adults show a consistent functional fingerprint whereby, pRF location, pRF size, and visual field coverage vary by category-selectivity, stream, and hemisphere. While pRF location is largely adult-like by adolescence, pRF size, visual field coverage, and category-selectivity exhibit region-specific increases and decreases from adolescence to adulthood. Together, these findings delineate a timeline of continued functional plasticity during adolescence and provide a multidimensional framework for understanding the organization of high-level visual cortex.

neuroscience↗

Visuospatial computations vary by category and stream and continue to develop in adolescence

Reading, face recognition, and navigation are supported by visuospatial computations in category-selective regions across ventral, lateral, and dorsal visual streams. However, the nature of visuospatial computations across streams and their development in adolescence remain unknown. Using fMRI and population receptive field (pRF) modeling in adolescents and adults, we estimate pRFs in high-level visual cortex and determine their development. Results reveal that pRF location, size, and visual field coverage vary across category, stream, and hemisphere in both adolescents and adults. While pRF location is mature by adolescence, pRF size and visual field coverage continue to develop - increasing in face-selective and decreasing in place-selective regions - alongside similar development of category selectivity. These findings provide a timeline for differential development of visual functions and suggest that visuospatial computations in high-level visual cortex continue to be optimized to accommodate both category and stream demands through adolescence.

neuroscience↗

A single computational objective drives specialization of streams in visual cortex

Human visual cortex is organized into dorsal, lateral, and ventral streams. A long-standing hypothesis is that the functional organization into streams emerged to support distinct visual behaviors. Here, we compare neural network-based computational models against a massive fMRI dataset to investigate why visual streams emerge. We find that a self-supervised Topographic Deep Artificial Neural Network (TDANN), which encourages nearby units to respond similarly, better captures brain responses, as well as spatial segregation and functional differentiation across streams, than DANN models trained for stream-specific visual behaviors. These findings challenge the prevailing view that streams evolved to separately support different behaviors and suggest instead the possibility that functional organization can arise from a single principle: learning generally useful visual representations subject to local spatial constraints.

neuroscience↗

A Unifying Principle for the Functional Organization of Visual Cortex

A key feature of many cortical systems is functional organization: the arrangement of neurons with specific functional properties in characteristic spatial patterns across the cortical surface. However, the principles underlying the emergence and utility of functional organization are poorly understood. Here we develop the Topographic Deep Artificial Neural Network (TDANN), the first unified model to accurately predict the functional organization of multiple cortical areas in the primate visual system. We analyze the key factors responsible for the TDANNs success and find that it strikes a balance between two specific objectives: achieving a task-general sensory representation that is self-supervised, and maximizing the smoothness of responses across the cortical sheet according to a metric that scales relative to cortical surface area. In turn, the representations learned by the TDANN are lower dimensional and more brain-like than those in models that lack a spatial smoothness constraint. Finally, we provide evidence that the TDANNs functional organization balances performance with inter-area connection length, and use the resulting models for a proof-of-principle optimization of cortical prosthetic design. Our results thus offer a unified principle for understanding functional organization and a novel view of the functional role of the visual system in particular.

neuroscience↗

Longitudinal development of category representations in ventral temporal cortex predicts word and face recognition

Regions in ventral temporal cortex (VTC) that are involved in visual recognition of categories like words and faces, undergo differential development during childhood. However, categories are also represented in distributed responses across VTC. How do distributed category representations develop and relate to behavioral changes in recognition? Here, we used fMRI to longitudinally measure the development of distributed responses across VTC to 10 categories in school-age children over several years. Our results reveal both strengthening and weakening of category representations with age, which was mainly driven by changes across category-selective voxels. Representations became particularly more distinct for words in the left hemisphere and for faces bilaterally. Critically, distinctiveness for words and faces across category-selective voxels in left and right lateral VTC, respectively, predicted individual childrens word and face recognition performance. These results suggest that the development of distributed VTC representations has behavioral ramifications and advance our understanding of prolonged cortical development during childhood.

neuroscience↗

White matter connections of high-level visual areas predict cytoarchitecture better than category-selectivity

Ventral temporal cortex (VTC) consists of high-level visual regions that are arranged in consistent anatomical locations across individuals. This consistency has led to several hypotheses about the factors that constrain the functional organization of VTC. A prevailing theory is that white matter connections influence the organization of VTC, however, the nature of this constraint is unclear. Here, we test two hypotheses: (1) white matter tracts are specific for each category or (2) white matter tracts are specific to cytoarchitectonic areas of VTC. To test these hypotheses, we used diffusion magnetic resonance imaging (dMRI) to identify white matter tracts and functional magnetic resonance imaging (fMRI) to identify category-selective regions in VTC in children and adults. We find that in childhood, white matter connections are linked to cytoarchitecture rather than category-selectivity. In adulthood, however, white matter connections are linked to both cytoarchitecture and category-selectivity. These results suggest a rethinking of the view that category-selective regions in VTC have category-specific white matter connections early in development. Instead, these findings suggest that the neural hardware underlying the processing of categorical stimuli may be more domain-general than previously thought, particularly in childhood.

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Holistic face recognition is an emergent phenomenon of spatial integration in face-selective regions

Spatial processing by receptive fields is a core property of the visual system. However, it is unknown how spatial coding in high-level regions contributes to recognition behavior. As face inversion is thought to disrupt typical holistic processing of information in faces, we mapped population receptive fields (pRFs) with upright and inverted faces in the human visual system. In face-selective regions, but not primary visual cortex, pRFs and overall visual field coverage were smaller and shifted downward in response to face inversion. From these measurements, we successfully predicted the relative behavioral detriment of face inversion at different positions in the visual field. This correspondence between neural measurements and behavior demonstrates how spatial integration in face-selective regions enables holistic processing. These results not only show that spatial processing in high-level visual regions is dynamically used towards recognition, but also suggest a powerful approach for bridging neural computations by receptive fields to behavior.

neuroscience↗

Cortical recycling in high-level visual cortex during childhood development

Human ventral temporal cortex (VTC) contains category-selective regions that respond preferentially to ecologically-relevant categories such as faces, bodies, places, and words, which are causally involved in the perception of these categories. How do these regions develop during childhood? We used functional MRI to measure longitudinal development of category-selectivity in school-age children over 1 to 5 years. We discovered that from young childhood to the teens, face- and word-selective regions in VTC expand and become more category-selective, but limb-selective regions shrink and lose their preference for limbs. Critically, as a child develops, increases in face- and word-selectivity are directly linked to decreases in limb-selectivity, revealing that during childhood limb-selectivity in VTC is repurposed into word- and face-selectivity. These data provide evidence for cortical recycling during childhood development. This has important implications for understanding typical as well as atypical brain development and necessitates a rethinking of how cortical function develops during childhood.

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Differential spatial processing in ventral and lateral face-selective regions is scaffolded by structural connections

Face-processing occurs across ventral and lateral visual streams, which are involved in static and dynamic face perception, respectively. However, the nature of spatial computations across streams is unknown. Using functional MRI and novel population receptive field (pRF) mapping, we measured pRFs in face-selective regions. Results reveal that spatial computations by pRFs in ventral face-selective regions are concentrated around the center of gaze (fovea), but spatial computations in lateral face-selective regions extend peripherally. Diffusion MRI reveals that these differences are mirrored by a preponderance of white matter connections between ventral face-selective regions and foveal early visual cortex (EVC), while connections with lateral regions are distributed more uniformly across EVC eccentricities. These findings suggest a rethinking of spatial computations in face-selective regions, showing that they vary across ventral and lateral streams, and further propose that spatial computations in high-level regions are scaffolded by the fine-grain pattern of white matter connections from EVC.

neuroscience↗