Biology subjects

Arcaro, M.

Publications and source records attributed to Arcaro, M..

11 recordsLinked to original sources

bioRxiv2026

Primary and higher-order thalamic nuclei make distinct contributions to cortical reorganization in congenital sensory loss

Early sensory loss transforms the functional organization of affected sensory systems, with regions that normally support vision or audition participating in noncanonical perceptual and cognitive functions. Such reorganization requires coordination across distributed networks. Higher-order thalamic nuclei are positioned to support these interactions through their widespread reciprocal cortical connectivity, yet studies of sensory-loss plasticity have focused primarily on cortex and first-order sensory pathways. Here, we combined structural and functional MRI in early blind and early deaf adults to test how reorganization after sensory loss is expressed across thalamocortical networks. In blindness, structural differences were concentrated along the primary input pathway, with reduced lateral geniculate nucleus volume that covaried with areal organization of primary visual cortex. Functional reorganization was more broadly distributed, with visual cortex showing greater similarity with higher-order (association) thalamic nuclei linked to cognitive control, paralleling a shift toward cognitive-control networks across cortex. This pattern was amplified during a nonvisual perceptual judgment task. Across visual cortex, cross-network functional differences were strongest in regions showing the largest structural effects. A related shift toward control-associated higher-order thalamus was observed in deafness, indicating that higher-order thalamic involvement generalizes across sensory modalities. Together, these results indicate that thalamocortical architecture shapes both the developmental consequences of early sensory loss and the capacity for distributed functional reorganization.

neuroscience↗

bioRxiv2026

Cascading periods of language-related brain plasticity across early childhood

Language is thought to have multiple sensitive periods in early childhood, but the neural basis of these sensitive periods is less understood. We leverage advances in in-vivo neuroimaging of plasticity, measuring the neural inhibition across the brain via Hurst exponent. Using two large datasets with children ages 10 months to 18 years (Baby Connectome Project: 10m-3y6m, 458 observations across n=222 children; Human Connectome Project-Development: 5-18y, n=437), we characterize the development of the Hurst exponent in language-related brain regions. In early childhood, Hurst increases in temporal and frontal language areas, and posterior regions develop earlier than anterior regions. In contrast, thalamic Hurst plateaus earlier, perhaps underlying the earliest language-related sensitive periods. Children with higher language-related skills show slower increases in cortical Hurst in early childhood, suggesting protracted plasticity. Later in childhood, cortical Hurst plateaus around age 9, suggesting a potential neural mechanism for age-related declines syntax learning. These results highlight a potential neural basis for cascading language-related sensitive periods. Research highlightsO_LILanguage has multiple, cascading sensitive periods, but the neural basis of these sensitive periods is not well-understood. C_LIO_LIWe leverage advances in in-vivo neuroimaging to quantify plasticity in language-related brain regions across childhood via Hurst, a measure of inhibition. C_LIO_LIWe find that Hurst increases (plasticity decreases) in a graded fashion, with posterior regions maturing before anterior regions. C_LIO_LIThalamic hurst plateaus in the first year of life, while cortical Hurst plateaus at age 9, suggesting a neural basis for distinct language-related sensitive periods. C_LI

developmental biology↗

bioRxiv2025

Functional organization of the human visual system at birth and across late gestation

Understanding how the brains functional architecture emerges prior to substantial postnatal visual experience is crucial for determining what initial capabilities infants possess and how they learn from their environment. Using resting-state fMRI from 584 neonates in the Developing Human Connectome Project, we provide the first comprehensive systems-level characterization of human visual cortex within hours of birth and across the third trimester of gestation. We discover that newborns possess a sophisticated visual architecture already functionally organized into three distinct pathways (ventral, lateral, and dorsal), each exhibiting posterior-to-anterior hierarchical structure and adult-like topographic organization. This tripartite visual organization differs from the bipartite organization observed in macaques, suggesting this architecture emerges through intrinsic developmental mechanisms rather than being a product of extensive postnatal experience and environmental adaptation. Moreover, pathway segregation, hierarchical ordering, and connectivity maturity all strengthen progressively with gestational age, revealing that visual cortical organization emerges through an active developmental program that unfolds across late gestation. Yet, despite this large-scale structure, individual pathways follow strikingly different maturation trajectories: dorsal areas exhibit a near-adult-like functional organization, even at the earliest gestational timepoints tested, whereas ventral areas remain immature and poised for experience-dependent refinement. These findings reframe our understanding of early visual development by revealing that complex functional networks emerge before substantial visual experience, yet are differentially prepared for plasticity, providing crucial insights into how evolution has optimized the brain for rapid learning while maintaining the flexibility needed for adaptation to diverse environments.

neuroscience↗

bioRxiv2025

Alcohol impacts an fMRI marker of neural inhibition in humans and rodents.

Acute alcohol consumption leads to cognitive and behavioral disinhibition that increase health and social risks, such as traffic fatalities and violence. Although rodent studies have shown that alcohol affects inhibitory neuronal activity, its relevance to humans remains largely unexplored. Here, we used the Hurst exponent--an fMRI-based marker of neural inhibition--to examine alcohols effects in both rats and humans. In rats, acute alcohol administration significantly reduced the cortical Hurst exponent, suggesting a decrease in inhibitory neuronal activity. This reduction was strongly correlated with the spatial distribution of GABAA receptor expression, highlighting the key role of these receptors in mediating alcohols effects. Similarly, in humans, acute alcohol consumption reduced the cortical Hurst exponent, especially in brain regions with high GABAA receptor expression. Our findings provide cross-species in vivo evidence that acute alcohol consumption modulates neural inhibition, offering new insights into the neural mechanisms underlying alcohol-induced behavioral modulation.

neuroscience↗

bioRxiv2025

Myelination across cortical hierarchies and depths in humans and macaques

Myelination is fundamental to brain function, enabling rapid neural communication and supporting neuroplasticity throughout the lifespan. While hierarchical patterns of myelin maturation across the cortical surface are well-documented in humans, it remains unclear which features reflect evolutionarily conserved developmental processes versus human-characteristic adaptations. Moreover, the laminar development of myelin across the primate cortical surface, which shapes hierarchies and supports functions ranging from sensory integration to network communication, has been largely unexplored. Using neuroimaging to measure the T1-weighted/T2-weighted ratio in tissue contrast as a proxy for myelin content, we systematically compared depth-dependent trajectories of myelination across the cortical surface in humans and macaques. We identified a conserved "inside-out" pattern, with deeper layers exhibiting steeper increases in myelination and earlier plateaus than superficial layers. This depth-dependent organization followed a hierarchical gradient across the cortical surface, progressing from early maturation in sensorimotor regions to prolonged development in association areas. Humans exhibited a markedly extended timeline of myelination across both cortical regions and depths compared to macaques, allowing for prolonged postnatal plasticity across the entire cortical hierarchy -- from sensory and motor processing to higher-order association networks. This extended potential for plasticity may facilitate the shaping of cortical circuits through postnatal experience in ways that support human-characteristic perceptual and cognitive capabilities.

developmental biology↗

bioRxiv2024

An intrinsic hierarchical, retinotopic organization of pulvinar connectivity in the human neonate

Thalamic connectivity is crucial for the development of the neocortex. The pulvinar nuclei are thought to be particularly important for visual development due to their involvement in various functions that emerge early in infancy. The development of these connections constrains the role the pulvinar plays in infant visual processing and the maturation of associated cortical networks. However, the extent to which pulvino-cortical pathways found in adults are established at birth remains largely unknown, limiting our understanding of how these thalamic connections may support infant vision. To address this gap, we examined the organization of pulvino-cortical connections in human neonates using probabilistic tractography analyses on diffusion imaging data. Our findings revealed the presence of white matter pathways between the pulvinar and each individual visual area at birth. These pathways exhibited specificity in their connectivity within the pulvinar, reflecting both intraareal retinotopic organization and the hierarchical organization across ventral, lateral, and dorsal visual cortical pathways. These connections could enable detailed processing of information across sensory space and communication along distinct processing pathways. Comparative analyses revealed that the large-scale organization of pulvino-cortical connectivity in neonates mirrored that of adults. However, connectivity with ventral visual cortex was less adult-like than the other cortical pathways, aligning with prior findings of protracted development associated with the visual recognition pathway. These results deepen our understanding of the developmental trajectory of thalamocortical connections and provide a framework for how subcortical structures may support early perceptual abilities and scaffold the development of cortex.

neuroscience↗

bioRxiv2020

Anatomical correlates of face patches in macaque inferotemporal cortex

Primate brains typically have regions within the ventral visual stream that are selectively responsive to faces. These face patches are located in similar parts of macaque inferotemporal (IT) cortex across individuals though correspondence with particular anatomical features has not been previously reported. Here, using high resolution functional and anatomical imaging, we show that small "bumps" along the lower bank of the superior temporal sulcus are predictive of the location of face-selective regions. Recordings from implanted multi-electrode arrays verified that these bumps contain face-selective neurons. These bumps were present in monkeys raised without seeing faces and that lack face patches, indicating that these anatomical landmarks are predictive, of but not sufficient for, the presence of face selectivity. These bumps are found across primate species, indicating common evolutionary developmental mechanisms.

neuroscience↗

bioRxiv2020

Sulcal depth in medial ventral temporal cortex predicts the location of a place-selective region in macaques, children, and adults.

The evolution and development of anatomical-functional relationships in the cerebral cortex is of major interest in neuroscience. Here, we leveraged the fact that a functional region selective for visual scenes is located within a sulcus in medial ventral temporal cortex (VTC) in both humans and macaques to examine the relationship between sulcal depth and place-selectivity in medial VTC across species and age groups. To do so, we acquired anatomical and functional magnetic resonance imaging scans in 9 macaques, 26 human children, and 28 human adults. Our results revealed a strong structural-functional coupling between sulcal depth and place-selectivity across age groups and species in which selectivity was strongest at the deepest sulcal point (the sulcal pit). Interestingly, this coupling between sulcal depth and place-selectivity strengthens from childhood to adulthood in humans. Morphological analyses suggest that the stabilization of sulcal-functional coupling in adulthood may be due to sulcal deepening and areal expansion with age as well as developmental differences in cortical curvature at the pial, but not the white matter surfaces. Our results implicate sulcal features as functional landmarks in high-level visual cortex and highlight that sulcal-functional relationships in medial VTC are preserved between macaques and humans despite differences in cortical folding.

neuroscience↗

bioRxiv2019

Body-map proto-organization in newborn macaques

Topographic sensory maps are a prominent feature of the adult primate brain. Here, we asked whether topographic representations of the environment are fundamental to early development. Using fMRI, we find that the newborn somato-motor system, spanning frontoparietal cortex and subcortex, comprises multiple topographic body representations. The organization of these large-scale body maps was indistinguishable from those in adults and already exhibited features stereotypical of adult maps. Finer-scale differentiation of individual fingers increased over the first two years, suggesting that topographic representations are refined during early development. Last, we found that somato-motor representations were unchanged in two visually impaired monkeys who relied entirely on touch for interacting with their environment, demonstrating that massive shifts in early sensory experience in an otherwise anatomically intact brain are not sufficient for driving cross-modal plasticity. We propose that a topographic scaffolding is present at birth that both directs and constrains experience-driven modifications throughout sensory systems.

neuroscience↗

bioRxiv2017

Elucidating relations between fMRI, ECoG and EEG through a common natural stimulus

Human brain mapping relies heavily on fMRI, ECoG and EEG, which capture different physiological signals. Relationships between these signals have been established in the context of specific tasks or during resting state, often using spatially confined concurrent recordings in animals. But it is not certain whether these correlations generalize to other contexts relevant for human cognitive neuroscience. Here, we address the case of complex naturalistic stimuli and ask two basic questions. First, how reliable are the responses evoked by a naturalistic audio-visual stimulus in each of these imaging methods, and second, how similar are stimulus-related responses across methods? To this end, we investigated a wide range of brain regions and frequency bands. We presented the same movie clip twice to three different cohorts of subjects (NEEG = 45, NfMRI = 11, NECoG = 5) and assessed stimulus-driven correlations across viewings and between imaging methods, thereby ruling out task-irrelevant confounds. All three imaging methods had similar repeat-reliability across viewings when fMRI and EEG data were averaged across subjects, highlighting the potential to achieve large signal-to-noise ratio by leveraging large sample sizes. The fMRI signal correlated positively with high-frequency ECoG power across multiple task-related cortical structures but positively with low-frequency EEG and ECoG power. In contrast to previous studies, these correlations were as strong for low-frequency as for high frequency ECoG. We also observed links between fMRI and infra-slow EEG voltage fluctuations. These results extend previous findings to the case of natural stimulus processing.

neuroscience↗

bioRxiv2017

Organizing principles of pulvino-cortical connectivity in humans

The pulvinar regulates information transmission to cortex and communication between cortical areas. The way the pulvinar interacts with cortex is governed by its intrinsic organization. Here, we show using fMRI that the human pulvinar is functionally heterogeneous, broadly separated into dorsal and ventral subdivisions based on characterization of response properties and functional connectivity with cortex. These differences mirrored the organization of the dorsal and ventral streams of visual cortex. The ventral subdivision of the pulvinar was functionally coupled with occipital and temporal cortex. The dorsal subdivision of the pulvinar was functionally coupled with frontal and parietal cortex. The dorsal subdivision was also coupled with the human-specific tool network and to the default mode network. The spatial organization of pulvino-cortical coupling reflected both the functional similarities and anatomical distances between cortical areas. Together, the human pulvinar appears to represent the entire visual system and the principles that govern its organization, though in a spatially compressed form.\n\nAuthor ContributionsMA, MP, and JC collected data; MA and JC analyzed the data; MA, MP, JC, and SK wrote the paper.

neuroscience↗