Biology subjects

Pedersini, C. A.

Publications and source records attributed to Pedersini, C. A..

3 recordsLinked to original sources

bioRxiv2025

Attention modulates the geometry of auditory representations

Selective attention enables the brain to prioritize behaviourally relevant information in complex environments, yet its neural mechanisms remain unclear. Here, we combined fMRI with representational geometry analyses to examine how attention reshapes neural population codes during naturalistic sound scenes. Participants attended to individual sound objects presented either with distractors from different categories (three objects across, 3OA) or the same category (three objects within, 3OW). Attention attracted neural population responses in low-dimensional manifolds toward the representation of each object presented in isolation, consistent with a reorganization of high-dimensional representational geometry. This effect depended on acoustic context: in 3OA, attended representations were significantly closer to object-alone representations than to distractors, whereas in 3OW attentional modulation was minimal. Category-specific effects were observed, with speech engaging left-lateralized language regions beyond the auditory cortex. Finally, stronger behavioural performance predicted greater representational attraction. These findings show that selective attention reshapes neural geometry in a context- and category-dependent manner closely linked to behaviour.

neuroscience↗

bioRxiv2024

Gray matter abnormalities in sight deprivation and sight restoration

Blindness provides a unique model for investigating brain plasticity in response to sensory deprivation. While structural changes in both gray and white matter have been widely documented, particularly in cases of early or congenital visual deprivation, gray matter studies have traditionally focused on cortical thickness, often finding cortical thickening in posterior regions. However, other aspects of gray matter integrity, such as cortical myelin content, remain underexplored. In this study, we examined the effects of visual deprivation on cortical structure in a cohort of congenitally blind individuals who received eye surgery during adolescence, expanding beyond conventional measures to include cortical thickness, curvature, and T1-weighted signal intensity. This multi-faceted approach offers a more comprehensive view of cortical adaptations to congenital sensory deprivation. While blindness offers valuable insights into sensory-driven brain plasticity, an intriguing and unresolved question is whether structural plasticity reverses after sight restoration, enabling typical visual processing circuits to develop despite the initial period of deprivation. To address this, we assessed the effect of sight-recovering eye surgery on gray matter changes. Critically, individuals in this cohort received surgery after the closure of the sensitive period for visual development. We did not find evidence of gray matter changes after surgery. However, in a previous study conducted on the same cohort, we reported that notable plasticity in white matter emerged in this same population. These results suggest that white matter alterations, rather than gray matter changes, may potentially serve as a biomarker of structural plasticity following sight restoration, even beyond the sensitive developmental window.

neuroscience↗

bioRxiv2024

Characterizing dynamic functional connectivity in congenitally blind people using Hidden Markov Models

How sensory experience shapes the organization of the human brain connectome remains a central question in neuroscience. Previous studies of congenital blindness have primarily relied on stationary functional connectivity, potentially overlooking how sensory deprivation affects the temporal reconfiguration of large-scale brain networks. Here, we investigated dynamic functional connectivity in blindness by comparing resting-state fMRI data from sighted (n = 50) and early blind individuals (n = 33) using a data-driven hidden Markov model approach. Early blind individuals exhibited increased fractional occupancy of two brain states characterized by bilateral somatomotor and left-lateralized occipito-frontal networks, whereas sighted participants more frequently occupied a state dominated by default mode and ventral attention networks. Connectivity states preferentially expressed by sighted participants showed reduced visual-somatomotor coupling in blind individuals, while states more frequently visited by early blind participants exhibited enhanced connectivity within the visual network and between occipital, fusiform, and prefrontal regions. Critically, the hyperconnectivity in blindness was largely explained by altered state occupancy, indicating that temporal dynamics, rather than connectivity patterns per se, drive reorganization. Beyond temporal dynamics, visual deprivation altered the spatial organization of functional gradients derived from model-based, state-specific connectivity: occipital regions shifted closer to transmodal networks, while the overall low-dimensional geometry of latent states remained largely preserved. This suggests that early visual deprivation selectively reshapes the temporal expression and functional embedding of brain states without altering the core scaffold of large-scale dynamics. Together, these findings demonstrate that blindness reshapes both the temporal and spatial structure of large-scale brain networks, highlighting the chronnectome as a critical substrate of experience-dependent plasticity. Significance StatementBlindness provides a unique opportunity to understand how the human brain reorganizes in the absence of typical sensory experience. Previous studies have relied on stationary functional connectivity, overlooking the role of temporal network dynamics. Using a data-driven Hidden Markov Model approach applied to resting-state fMRI, we show that early visual deprivation primarily alters the temporal dynamics of brain states. Crucially, the hyperconnectivity classically observed in early blind individuals emerges from changes in state occupancy rather than intrinsic alterations of connectivity patterns. Beyond temporal effects, we also demonstrate that visual deprivation reshapes functional gradients, with occipital regions shifting toward transmodal systems. Together, these findings reveal the chronnectome as a key mechanism of experience-dependent plasticity, while preserving a robust large-scale organizational scaffold.

neuroscience↗