2026-09-18T18:33:05Zhttps://publikationen.uni-tuebingen.de/oai/requestoai:publikationen.uni-tuebingen.de:10900/1723482025-12-08T13:52:28Zcom_10900_42126col_10900_42130
Publikationssystem UB Tuebingen
advisor
Kuehn, Esther (Prof. Dr.)
author
Kalyani, Avinash
2025-11-19T11:23:26Z
2025-11-19
http://hdl.handle.net/10900/172348
Functional Magnetic Resonance Imaging (fMRI), particularly at ultra-high-field strengths such as 7-Tesla (7T), has revolutionized neuroscience by enabling detailed exploration of the human brain’s functional architecture. This thesis leverages the advanced spatial resolution of 7T-fMRI to investigate the sensorimotor cortex, focusing on age-related changes and disease-specific alterations associated with Amyotrophic Lateral Sclerosis (ALS). While the unprecedented resolution of 7T-fMRI allows for the analysis of fine-grained features, such as cortical columns and laminar structures, the high dimensionality and complexity of the data necessitate sophisticated analytical methods.
This work employs 7 T task-based fMRI with advanced multivariate techniques, including Robust Shared Response Modeling (rSRM), Columnar Shared Response Modeling (C-SRM) (introduced as a novel method), and Partial Least Squares Regression (PLSR), to address the challenges posed by high-dimensional fMRI data. SRM and C-SRM are utilized to align functional data across participants and examine fine-scale neural organization, particularly at the columnar level, while PLSR links neural activity to clinical and behavioral outcomes. These approaches enable the identification of both shared and individual-specific neural patterns, offering a nuanced understanding of functional changes in the sensorimotor cortex.
In the context of aging, rSRM and C-SRM show that the hierarchical layout of Brodmann areas (BA) 3b → 1 → 2 is preserved in older adults, yet digit representations become less precise. In BA1, the optimal number of functional columns drops relative to young adults, indicating enlarged, less se- lective columns; while BA3b remains stable. These findings reveal a subtle dedifferentiation—blurred maps but an intact hierarchy—consistent with compensatory pooling of sensory inputs.
In ALS, rSRM combined with PLSR distinguishes patients from controls with high accuracy based on task-evoked BOLD patterns. Connectivity-derived latent variables outperform activation maps in clustering disease onset site and staging, and they exhibit an atopographic signature: foot and face regions of MI track progression regardless of the initial symptom locus. The data suggest an early, network-wide hyper-connective compensation that collapses as degeneration advances.
Together, these results validate advanced alignment and dimensionality-reduction strategies for extracting fine grained insights from 7 T data. They establish enlarged columns as a fingerprint of healthy ageing and identify network-level connectivity markers for ALS staging—outcomes that can guide larger multicentre, multimodal studies and inform therapeutic efforts aimed at preserving sensorimotor function across the lifespan and in neurodegenerative disease.
en
ubt-podno
Mapping Age- and ALS-Related Changes in the Sensorimotor Cortex with Multivariate 7T-fMRI Analyses
PhDThesis
URL
https://publikationen.uni-tuebingen.de/xmlui/bitstream/10900/172348/1/thesis.pdf
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thesis.pdf
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https://publikationen.uni-tuebingen.de/xmlui/bitstream/10900/172348/2/thesis.pdf.txt
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thesis.pdf.txt