Biology subjects

Hatano, K.

Publications and source records attributed to Hatano, K..

5 recordsLinked to original sources

bioRxiv2026

Enabling Stable Cortical Reconstruction in the HCP Pipeline at Standard Resolution Using FastSurfer Integration with Hybrid T2w- and T1w-based Masking

This study aimed to enable stable cortical reconstruction within the Human Connectome Project (HCP) pipeline under standard-resolution (1 mm3) conditions by developing an integrated framework combining FastSurfer with a hybrid T2w- and T1w-based masking strategy. We implemented a FastSurfer-integrated HCP pipeline incorporating a hybrid masking approach (t2log-hybrid) to stabilize cortical reconstruction, where SynthStrip-derived masks were refined using log-transformed T2-weighted and squared T1-weighted images. An anterior commissure-anchored spatial switching mechanism selectively replaced artifact-prone T2w regions with T1w-derived information in orbitofrontal areas. Performance was evaluated against FreeSurfer v6 (FS6), v7 (FS7), and FastSurfer using geometric agreement, regional consistency, and vertex-wise thickness-myelin analyses. The proposed framework reduced total processing time by over 50% compared with FS6 and maintained high geometric agreement with modern pipelines (vertex-wise r = 0.970 vs FastSurfer; r = 0.929 vs FS7). Agreement with FS6 was lower (r = 0.842), reflecting systematic differences in boundary definition rather than random error. The hybrid masking approach showed higher regional consistency and lower variability in T1w/T2w-derived myelin estimates (CV = 16.50% vs 40.56% in FastSurfer), with more spatially consistent thickness-myelin interaction patterns in artifact-prone ventral regions. Integrating FastSurfer into the HCP pipeline with hybrid T2w- and T1w-based masking enables stable cortical reconstruction by constraining signal-driven instability while preserving algorithm-dependent spatial organization. These findings highlight the importance of masking as a constraint on instability in cortical reconstruction and support the applicability of HCP-style analysis to clinical and legacy MRI datasets.

neuroscience↗

bioRxiv2025

Whole-Brain Millisecond-Scale Effective Connectivity Atlas of Auditory and Visual Naming

Neurobiological models suggest that speech relies on interactions among distant cortical regions interconnected by white matter pathways. Prior studies have shown that speech-related functional coactivation--simultaneous high-gamma augmentation across distributed regions--reflects underlying neural interactions, as validated by electrical stimulation mapping. However, it remains unclear at the whole-brain level when, for how long, and in which directions cortical regions transmit information, and how dynamic information flows contribute to speech. Here, we investigated the causal roles of directional neural information flow during auditory and visual naming using intracranial EEG from 9,526 artifact-free nonepileptic sites across 127 patients. Information flow, estimated by transfer entropy-based effective connectivity, was classified as excitatory when high-gamma acceleration in one region predicted subsequent acceleration in another, and inhibitory when deceleration predicted downstream deceleration. Following stimulus onset, excitatory flows emerged from modality-specific sensory cortices and propagated to higher-order regions, later becoming bidirectional as functional coactivation developed. Each excitatory flow event was transient (<500 ms), typically followed by inhibitory flows and decreased coactivation, during which excitatory flows often emerged along new pathways. During auditory naming, faster response times were associated with stronger excitatory flows in left perisylvian regions; during visual naming, faster responses were linked to stronger flows in bilateral basal temporal cortices. Stronger excitatory flows at specific time points predicted a higher probability of stimulation-induced symptoms (Spearmans rho: 0.54-0.81; p<0.00001), whereas associations with inhibitory flows peaked later. Excitatory flows near visual naming response onset were particularly associated with stimulation-induced speech arrest and face sensorimotor symptoms, whereas functional coactivation alone failed to reveal comparable associations. These findings demonstrate that transient acceleration of directional neural interactions through white matter supports successive stages of speech processing. As activity within one pathway decelerates, excitatory flow accelerates along another, enabling functional transitions critical for naming. By establishing the causal contribution of temporally precise, anatomically specific white matter pathways, this study substantiates and extends existing neurobiological models of speech. To facilitate replication and dynamic whole-brain visualization, we provide open access to the full dataset (62.15 GB) and analysis code.

neuroscience↗

bioRxiv2025

Dynamic Causal White Matter Atlas of Auditory and Visual Speech Networks at Millisecond Resolution: Intracranial Evidence from 125 Patients

Background and ObjectivesSince the era of Penfield, invasive neurophysiology has laid a lasting foundation for functional neuroscience by elucidating brain regions necessary for speech. However, whole-brain investigations have yet to distinguish the millisecond-scale dynamics and specific white matter pathways that support rapid naming in the auditory and visual domains. MethodsIn this observational study, we constructed a whole-brain Dynamic Causal Tractography atlas using intracranial neurophysiological data from 125 neurosurgical patients. The resulting video atlas captured local cortical high-gamma activity and cortico-cortical coactivation via white matter tracts during rapid and delayed auditory and picture naming. Direct electrical stimulation was employed to assess the causal significance of the observed neural dynamics. ResultsThe atlas revealed white matter coactivation intensity patterns at specific 5-millisecond time windows that best aligned with sensorimotor and language symptoms elicited by electrical stimulation (Spearmans {rho} = 0.58-0.91; p = 4.8 x 10cc to 1.6 x 10c{superscript 2}c). Rapid auditory naming was associated with deactivation of the right rostral middle frontal gyrus and increased coactivation along the left arcuate fasciculus, linked to stimulation-induced receptive and expressive aphasia. In contrast, delayed auditory naming correlated with a late surge in bifrontal coactivation. Rapid picture naming involved early coactivation between cortices connected via the bilateral inferior longitudinal fasciculi--associated with stimulation-induced visual distortions--coinciding with transient co-inactivation of Brocas area. DiscussionThese findings delineate dissociable white matter-mediated mechanisms supporting rapid naming in the auditory and visual domains. Reduced inhibitory monitoring by the right dorsolateral prefrontal cortex may facilitate efficient lexical retrieval via left perisylvian pathways during auditory naming. In contrast, excessive bifrontal interaction may underlie delayed auditory naming. Rapid visual object recognition appears to rely on early occipitotemporal coactivation with minimal involvement of Brocas area. The resulting atlas--accompanied by a publicly available dataset (61.2 GB) and analysis code--serves as a valuable resource for students and trainees studying the network dynamics underlying speech, as well as for presurgical language mapping in patients undergoing cortical or subcortical intervention.

neuroscience↗

bioRxiv2025

Millisecond-Scale White Matter Dynamics Underlying Visuomotor Integration

In the conventional neuropsychological model, nonverbal visuospatial processing is predominantly handled by the right hemisphere, whereas verbal processing occurs in the left, with right-hand responses governed by the left motor cortex. Using intracranial EEG and MRI tractography, we investigated the timing and white matter networks involved in processing nonverbal visuospatial stimuli, forming response decisions, and generating motor outputs. Within 200 ms of stimulus onset, we observed widespread increases in functional connectivity and bidirectional neural flows from visual to association cortices, predominantly in the right hemisphere. Engagement of the right anterior middle frontal gyrus improved response accuracy; however, the accompanying enhancement in intra-hemispheric connectivity delayed response times. In the final 100 ms before right-hand response, functional connectivity and bidirectional communication via the corpus callosum between the right and left motor cortices became prominent. These findings provide millisecond-level support for the established model of hemispheric specialization, while highlighting a trade-off between accuracy and speed governed by the right dorsolateral prefrontal network. They also underscore the critical timing of callosal transmission of response decisions formed in right-hemispheric networks to the left-hemispheric motor system. HighlightsNeural information propagates through fasciculi during a visuomotor task. Non-verbal visuospatial analysis is mediated with right-hemispheric dominance. The right middle frontal gyrus improves response accuracy but delays responses. Interhemispheric information transfer occurs immediately before motor responses. This transfer between motor cortices is mediated by the corpus callosum.

neuroscience↗

bioRxiv2020

Understanding the impact of preprocessing pipelines on neuroimaging cortical surface analyses

The choice of preprocessing pipeline introduces variability in neuroimaging analyses that affects the reproducibility of scientific findings. Features derived from structural and functional MR imaging data are sensitive to the algorithmic or parametric differences of preprocessing tasks, such as image normalization, registration, and segmentation to name a few. Therefore it is critical to understand and potentially mitigate the cumulative biases of pipelines in order to distinguish biological effects from methodological variance. Here we use an open structural MR imaging dataset (ABIDE), supplemented with the Human Connectome Project (HCP), to highlight the impact of pipeline selection on cortical thickness measures. Specifically, we investigate the effect of 1) software tool (e.g. ANTs, CIVET, FreeSurfer), 2) cortical parcellation (DKT, Destrieux, Glasser), and 3) quality control procedure (manual, automatic). We divide our statistical analyses by 1) method type, i.e. task-free (unsupervised) versus task-driven (supervised), and 2) inference objective, i.e. neurobiological group differences versus individual prediction. Results show that software, parcellation, and quality control significantly impact task-driven neurobiological inference. Additionally, software selection strongly impacts neurobiological and individual task-free analyses, and quality control alters the performance for the individual-centric prediction tasks. This comparative performance evaluation partially explains the source of inconsistencies in neuroimaging findings. Furthermore, it underscores the need for more rigorous scientific workflows and accessible informatics resources to replicate and compare preprocessing pipelines to address the compounding problem of reproducibility in the age of large-scale, data-driven computational neuroscience.Competing Interest StatementThe authors have declared no competing interest.View Full Text

bioinformatics↗