Biology subjects

Braun, H.

Publications and source records attributed to Braun, H..

4 recordsLinked to original sources

bioRxiv2026

Prefrontal cortical pathways mediating cognitive control enhancement from internal capsule stimulation

BackgroundDeep brain stimulation (DBS) targeting the ventral internal capsule/ventral striatum (VCVS) is an effective treatment for several psychiatric disorders, but clinical responses often vary amongst patients likely due to an incomplete mechanistic understanding of the brain pathways mediating response. VCVS DBS can improve cognitive control, a core deficit in multiple psychiatric disorders. Here, we investigated which prefrontal cortical pathway(s) in the internal capsule are associated with improving cognitive control during VCVS DBS. MethodsFour participants with bilateral VCVS DBS completed the Multi-Source Interference Task (MSIT) under 27 stimulation settings varying by side (left/right lead), electrode, amplitude, and frequency. Each condition included 100 trials and response time (RT) assessed task performance. Personalized pathway activation models quantified axonal recruitment across 11 segmented prefrontal cortical fiber bundles per brain hemisphere. Associations between pathway activation and task RT were analyzed to identify circuits linked to improved cognitive control performance. ResultsRight-sided VCVS stimulation produced greater improvements in cognitive control (reductions in MSIT RT) than left-sided stimulation. Activation of right dorsal prefrontal cortical pathways connected to the dorsolateral prefrontal cortex (dlPFC) and dorsomedial prefrontal cortex (dmPFC) most strongly predicted faster MSIT RTs, whereas no left-sided pathways were associated with performance changes. ConclusionsThese findings suggest that the effects of VCVS DBS on cognitive control are primarily mediated by right dorsal prefrontal cortical axons projecting from the dlPFC and dmPFC. Targeting these pathways may improve stimulation strategies and outcomes for psychiatric disorders characterized by impaired cognitive control.

neuroscience↗

bioRxiv2025

Development and validation of an ultra-low-cost, open source normothermic ex vivo organ perfusion platform

BackgroundNormothermic ex vivo organ perfusion (NEVOP) promises to catalyze organ preservation, therapeutic discovery, and organ-specific disease modeling. Existing technology platforms remain inaccessible for research due to restricted access to commercial organ perfusion devices, high costs of both devices and proprietary consumables, and steep technical learning curves. Additionally, the available technology is not optimized to perfuse smaller organs such as the kidney. MethodsTo overcome these barriers, a custom NEVOP circuit was developed using recycled, repurposed, and low-cost components. Porcine kidneys and autologous blood were used to iteratively optimize circuit design. A porcine kidney autotransplantation protocol was adapted to evaluate in vivo kidney function after ex vivo perfusion. To pilot the flexibility of this system as a multi-organ platform for ex vivo human biology, non-transplantable human donor kidney, spleen, and pancreas specimens were stably perfused using human blood products and analyzed. ResultsAn ultra low-cost NEVOP system engineered to perfuse porcine kidneys and diverse human organs (kidney, pancreas, and spleen) sustained viable organs for up to 24 hours with evidence of both function and viability. Key innovations included a parallel flow resistor to facilitate low-flow perfusion in non-heparinized organs and a containment bag with adjustable magnets to provide vascular stability and recycling of venous overflow. The circuit costs less than 1,500USD to construct, and porcine kidneys perfused for 24 hours on this platform demonstrated healthy in vivo function upon autotransplantation. ConclusionsCustom NEVOP platforms constitute novel and potentially transformative research platforms which use low-cost and readily available materials. Paired with access to non-transplantable research organs from altruistic donors, this model provides a road map for investigators to advance biomedical discovery and human ex vivo biology.

bioengineering↗

bioRxiv2022

ZNF524 directly interacts with telomeric DNA and supports telomere integrity

Telomeres are nucleoprotein structures at the ends of linear chromosomes. In humans, they consist of TTAGGG repeats, which are bound by dedicated proteins such as the shelterin complex. This complex blocks unwanted DNA damage repair at telomeres, e.g. by suppressing non-homologous end joining (NHEJ) through its subunit TRF2. We here describe ZNF524, a zinc finger protein that directly binds telomeric repeats with nanomolar affinity and reveal the base-specific sequence recognition by co-crystallization with telomeric DNA. ZNF524 localizes to telomeres and specifically maintains the presence of the TRF2/RAP1 subcomplex at telomeres without affecting other shelterin members. Loss of ZNF524 concomitantly results in an increase in DNA damage signaling and recombination events. Overall, ZNF524 is a direct telomere-binding protein involved in the maintenance of telomere integrity.

cell biology↗

bioRxiv2020

Deep-learning based fully automatic segmentation of the globus pallidus interna and externa using ultra-high 7 Tesla MRI

Deep brain stimulation (DBS) surgery has been shown to dramatically improve the quality of life for patients with various motor dysfunctions, such as those afflicted with Parkinsons disease (PD), dystonia, and essential tremor (ET), by relieving motor symptoms associated with such pathologies. The success of DBS procedures is directly related to the proper placement of the electrodes, which requires the ability to accurately detect and identify relevant target structures within the subcortical basal ganglia region. In particular, accurate and reliable segmentation of the globus pallidus (GP) interna is of great interest for DBS surgery for PD and dystonia. In this work, we present a deep-learning based neural network, which we term GP-net, for the automatic segmentation of both the external and internal segments of the globus pallidus. High resolution 7 Tesla images from 101 subjects were used in this study; GP-net is trained on a cohort of 58 subjects, containing patients with movement disorders as well as healthy control subjects. GP-net performs 3D inference in a patient-specific manner, alleviating the need for atlas-based segmentation. GP-net was extensively validated, both quantitatively and qualitatively over 43 test subjects including patients with movement disorders and healthy control and is shown to consistently produce improved segmentation results compared with state-of-the-art atlas-based segmentations. We also demonstrate a post-operative lead location assessment with respect to a segmented globus pallidus obtained by GP-net.

neuroscience↗