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.