Biology subjects

Lueckel, M.

Publications and source records attributed to Lueckel, M..

3 recordsLinked to original sources

bioRxiv2026

Objective Quality Assessment for Precision Functional MRI Data

Precision functional mapping (PFM) enables individual-level characterization of brain network organization but requires substantially more and higher-quality fMRI data than is standard. Despite its growing use, objective criteria for data sufficiency and quality needed to ensure interpretable and replicable individual-level results remain unclear. Here, we introduce the Network Similarity Index (NSI), an objective measure of the extent to which functional connectivity (FC) patterns in an individual dataset express the large-scale network structure required for PFM. NSI captures the integrity of low-spatial-frequency, coherent network organization and denoising fidelity, and aligns closely with blinded expert assessments of PFM usability. NSI also accounts for variability in the rate at which FC becomes reliable across individuals. Here, we provide an open-source framework for NSI-based data quality evaluation and models for linking NSI values with expert-judged PFM suitability. This framework can also inform expected returns from additional data collection, enabling principled decisions about data sufficiency and replication in precision fMRI research.

neuroscience↗

bioRxiv2026

Optimizing Network-Level TMS-fMRI: Benchmarking a Novel TMS-Compatible "Sushi" MR Coil

Concurrent TMS-fMRI can map how stimulation affects both the targeted cortex and connected brain-wide networks, but this requires MR receive hardware that allows TMS coil placement while preserving reliable whole-brain BOLD sensitivity. We developed and benchmarked a practical TMS-compatible "Sushi" MR receive setup assembled from two flexible 18-channel body arrays. Across six experiments, we tested functional readout validity, signal quality, and active TMS-fMRI compatibility. Resting-state fMRI (n = 12) and verbal N-back task-fMRI (n = 8) were acquired with Sushi, a commercially available 2x7-channel Surface setup, and a standard 64-channel head/neck array. Functional similarity to the 64-channel reference was quantified with spatial overlap, and multi-echo combination (MEcomb) was tested as a post-acquisition signal optimization strategy. Sushi recovered subject-specific resting-state networks that more closely matched the 64-channel reference than Surface, with no significant difference from the 64-channel test-retest reference. For task-fMRI, MEcomb increased task-map similarity for Sushi, whereas setup comparisons within each pipeline were not significant. MEcomb also improved resting-state similarity and increased temporal signal-to-noise ratio (tSNR) across receive setups. In phantom measurements, TMS coil placement produced spatially graded tSNR reductions relative to the no-TMS-coil condition, strongest near the coil. In one participant, active interleaved single-pulse TMS-fMRI over two cortical sites showed no detectable pulse-locked image artifacts; whole-brain MEcomb tSNR during active TMS-fMRI was reduced by 2.6-6.9% relative to the no-coil/no-stimulation reference. Together, Sushi and MEcomb provide complementary hardware and processing tools for TMS-compatible whole-brain fMRI. This combination supports network-level functional readouts while preserving feasibility for active interleaved TMS-fMRI.

neuroscience↗

bioRxiv2025

Modulating Brain Perfusion, Functional Connectivity, and Metabolite Patterns through Theta Burst Transcranial Focused Ultrasound Stimulation

BackgroundTranscranial ultrasonic stimulation (TUS) is an emerging non-invasive neuromodulation technique with the potential to target both cortical and subcortical brain regions. This study investigates the effects of theta-burst TUS (tb-TUS), a neuromodulatory pattern characterized by bursts of pulses repeated at a theta frequency, on cerebral blood flow, functional connectivity, and metabolite concentrations in the primary motor cortex (M1). The aim of this study is to take a first step towards the mechanistic and methodological feasibility of tb-TUS at the M1 using multimodal neuroimaging. MethodsSeventeen healthy participants underwent a double-blind, sham-controlled crossover design, receiving both active and sham tb-TUS to the left M1 over three days. Multimodal MRI, including pseudo-continuous arterial spin labeling (PCASL), resting-state functional MRI (rs-fMRI), and magnetic resonance spectroscopy (MRS), was conducted at baseline, pre-, and post-stimulation. Acoustic simulations and finger-tapping BOLD-peak signal guided individualized TUS targeting. ResultsActive tb-TUS significantly reduced cerebral blood flow (p < .001) and within-region functional connectivity (p < .001) in the M1 compared to sham stimulation. A non-significant trend towards decreased GABA was observed, with no significant session x condition interaction found for GABA, Glutamate, or Glx concentrations. ConclusionThis pilot study demonstrates that tb-TUS of the M1 induces reductions in cerebral blood flow and functional connectivity in healthy participants. Our findings indicate that tb-TUS may be mitigating neural hyperactivity patterns, but preliminary studies so far arrive at differing results, highlighting the need for further research to replicate our findings, elucidate the underlying mechanisms, and optimize stimulation protocols.

physiology↗