Biology subjects

Rieger, S. W.

Publications and source records attributed to Rieger, S. W..

4 recordsLinked to original sources

bioRxiv2025

Dual-site beta transcranial alternating current stimulation during a bimanual coordination task modulates functional connectivity between motor areas

BackgroundCommunication within brain networks depends on functional connectivity. One promising approach to modulate such connectivity between cortical areas is dual-site transcranial alternating current stimulation (tACS), which non-invasively applies weak alternating currents to two brain areas. Objectives/HypothesesIn the current study, we aimed to modulate inter-regional functional connectivity with dual-site tACS to bilateral primary motor cortices (M1s) during bimanual coordination and, in turn, alter behaviour. MethodsUsing functional magnetic resonance imaging (fMRI), we recorded participants brain responses during a bimanual coordination task in a concurrent tACS-fMRI design. While performing a slow and fast version of the task, participants received one of three types of beta (20 Hz) dual-site tACS over both M1s: in-phase, jittered-phase or sham, in a within-subject, repeated measures design. ResultsWhile we did not observe any significant tACS effects on behaviour, the study revealed a disruptive effect of in-phase tACS on interhemispheric connectivity. Additionally, the two active types of tACS (in-phase and jittered-phase) differed in the task-related M1 connectivity with other motor cortical regions, such as premotor cortex and supplementary motor area. Furthermore, individual E-field strengths were related to functional connectivity in the in-phase condition. ConclusionsDual-site beta tACS over both M1s altered functional connectivity between motor areas. However, this effect did not translate to the behavioural level, possibly due to compensatory mechanisms. HighlightsO_LIInterhemispheric connectivity between the primary motor cortices was targeted with dual-site beta tACS during bimanual coordination. C_LIO_LIIn-phase as compared to sham tACS disrupted interhemispheric connectivity during task performance. C_LIO_LIIn-phase and jittered-phase tACS led to different task-related functional connectivity patterns within the motor network. C_LIO_LIThe relationship between individual in-phase E-field strengths and interhemispheric connectivity depended on task demand. C_LIO_LIThere were no significant tACS effects on behavioural performance of bimanual coordination, possibly due to compensatory mechanisms. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/647211v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@17ecdd8org.highwire.dtl.DTLVardef@1fc5b25org.highwire.dtl.DTLVardef@c3df42org.highwire.dtl.DTLVardef@17671bb_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Ultrasound system for precise neuromodulation of human deep brain circuits

Transcranial ultrasound stimulation (TUS) has emerged as a promising technique for non-invasive neuromodulation, but current systems lack the precision to target deep brain structures effectively. Here, we introduce an advanced TUS system that achieves unprecedented precision in deep brain neuromodulation. The system features a 256-element, helmet-shaped transducer array operating at 555 kHz, coupled with a stereotactic positioning system, individualised treatment planning, and real-time monitoring using functional MRI. In a series of experiments, we demonstrate the systems ability to selectively modulate the activity of the lateral geniculate nucleus (LGN) and its functionally connected regions in the visual cortex. Participants exhibited significantly increased visual cortex activity during concurrent TUS and visual stimulation, with high reproducibility across individuals. Moreover, a theta-burst TUS protocol induced robust neuromodulatory effects, with decreased visual cortex activity observed for at least 40 minutes post-stimulation. These neuromodulatory effects were specific to the targeted LGN, as confirmed by control experiments. Our findings highlight the potential of this advanced TUS system to non-invasively modulate deep brain circuits with high precision and specificity, offering new avenues for studying brain function and developing targeted therapies for neurological and psychiatric disorders. The unprecedented spatial resolution and prolonged neuromodulatory effects demonstrate the transformative potential of this technology for both research and clinical applications, paving the way for a new era of non-invasive deep brain neuromodulation.

neuroscience↗

bioRxiv2021

The Forget-Me-Not dHCP study: 7 Tesla high resolution diffusion imaging in the unfixed post-mortem neonatal brain

Diffusion MRI of the neonatal brain allows investigation of the organisational structure of maturing fibres during brain development. Post-mortem imaging has the potential to achieve high resolution by using long scan times, enabling precise assessment of small structures. The Forget-Me-Not study, part of the Developing Human Connectome Project (dHCP), aims to acquire and publicly distribute high-resolution diffusion MRI data for unfixed post-mortem neonatal brain at 7T with a custom-built head coil. This paper describes how the study addressed logistical, technical and ethical challenges relating to recruitment pipeline, care pathway, tissue preservation, scan setup and protocol optimisation. Results from the first subject recruited to the study demonstrate high-quality diffusion MRI data. Preliminary voxel-wise and tractography-based analyses are presented for the cortical plate, subplate and white matter pathways, with comparison to age-matched in vivo dHCP data. These results demonstrate that high quality post-mortem data can be acquired and provide a sensitive means to explore the developing human brain, as well as altered diffusion properties consistent with post-mortem changes, at high resolution.

bioengineering↗

bioRxiv2019

Tools and Resources: Remote, automated and MRI-compatible administration of interoceptive inspiratory resistive loading

Research on how humans perceive sensory inputs from their bodies ( interoception) has been rapidly gaining momentum, with interest across a host of disciplines from physiology through to psychiatry. However, studying interoceptive processes is not without significant challenges, and many methods utilised to access internal states have been largely devoted to capturing and relating naturally-occurring variations in interoceptive signals (such as heartbeats) to measures of how the brain processes these signals. An alternative procedure involves the controlled perturbation of specific interoceptive axes. This is challenging because it requires non-invasive interventions that can be repeated many times within a subject and that are potent but safe. Here we present an effective methodology for instigating these perturbations within the breathing domain. We describe a custom-built circuitry that is capable of delivering inspiratory resistive loads automatically and precisely. Importantly, our approach is compatible with magnetic resonance imaging environments, allowing for the administration of complicated experimental designs in neuroimaging as increasingly required within developing fields such as computational psychiatry/psychosomatics. We describe the experimental setup for both the control and monitoring of the inspiratory resistive loads, and demonstrate its possible utilities within different study designs. This methodology represents an important step forward from the previously utilised, manually-controlled resistive loading setups, which present significant experimental burdens with prolonged and/or complicated sequences of breathing stimuli.

neuroscience↗