Publications by authors named "Andreas Horn"

Gilles de la Tourette Syndrome (GTS) is a chronic tic disorder, characterized by unwanted motor actions and vocalizations. While brain stimulation techniques show promise in reducing tic severity, optimal target networks are not well-defined. Here, we leverage datasets from two independent deep brain stimulation (DBS) cohorts and a cohort of tic-inducing lesions to infer critical networks for treatment and occurrence of tics by mapping stimulation sites and lesions to a functional connectome derived from 1,000 healthy participants.

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Subthalamic (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) patients not only improves kinematic parameters of movement but also modulates cognitive control in the motor and non-motor domain, especially in situations of high conflict. The objective of this study was to investigate the relationship between DBS-induced changes in functional connectivity at rest and modulation of response- and movement inhibition by STN-DBS in a visuomotor task involving high conflict. During DBS ON and OFF conditions, we conducted a visuomotor task in 14 PD patients who previously underwent resting-state functional MRI (rs-fMRI) acquisitions DBS ON and OFF as part of a different study.

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Brain rhythms can facilitate neural communication for the maintenance of brain function. Beta rhythms (13-35 Hz) have been proposed to serve multiple domains of human ability, including motor control, cognition, memory, and emotion, but the overarching organisational principles remain unknown. To uncover the circuit architecture of beta oscillations, we leverage normative brain data, analysing over 30 hr of invasive brain signals from 1772 channels from cortical areas in epilepsy patients, to demonstrate that beta is the most distributed cortical brain rhythm.

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Article Synopsis
  • Disorders of consciousness (DoC) refer to conditions where a person has reduced awareness or ability to respond, and deep brain stimulation (DBS) is being explored as a treatment, with varying effectiveness based on patient specifics and stimulation methods.
  • In a study of 40 DoC patients receiving DBS, improved consciousness was linked to better gray matter preservation, particularly in the striatum, and effective stimulation targeted specific brain areas, particularly the thalamic centromedian-parafascicular complex.
  • The research highlights the need for precise electrode placement and suggests a connection between successful DBS treatment for DoC and mechanisms involved in other conditions that impair consciousness, such as absence seizures and brain lesions
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  • White matter hyperintensities (WMH) are linked to cognitive impairment but solely measuring their volume doesn't fully explain the cognitive deficits.
  • Lesion network mapping (LNM) offers a new way to assess how WMH connects with brain networks, potentially improving our understanding of their impact on cognition.
  • In a study of 3,485 patients, LNM scores outperformed WMH volumes in predicting cognitive performance, especially in attention, processing speed, and verbal memory, but not for language functions.
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Background: Stimulation of a specific site in the dorsolateral subthalamic nucleus (STN) was recently associated with slower motor progression in Parkinson's Disease (PD), based on the deep brain stimulation (DBS) in early-stage PD pilot clinical trial. Here, subject-level visualizations are presented of this early-stage PD dataset to further describe the relationship between active contacts and motor progression. This study also evaluates whether stimulation of the sweet spot and connectivity model associated with slower motor progression is also associated with improvements in long-term motor outcomes in patients with advanced-stage PD.

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Subcortical arousal systems are known to play a key role in controlling sustained changes in attention and conscious awareness. Recent studies indicate that these systems have a major influence on short-term dynamic modulation of visual attention, but their role across sensory modalities is not fully understood. In this study, we investigated shared subcortical arousal systems across sensory modalities during transient changes in attention using block and event-related fMRI paradigms.

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Background: Transcranial temporal interference stimulation (tTIS) is a new, emerging neurostimulation technology that utilizes two or more electric fields at specific frequencies to modulate the oscillations of neurons at a desired spatial location in the brain. The physics of tTIS offers the advantage of modulating deep brain structures in a non-invasive fashion and with minimal stimulation of the overlying cortex outside of a selected target. As such, tTIS can be effectively employed in the context of therapeutics for the psychiatric disease of disrupted brain connectivity, such as major depressive disorder (MDD).

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  • Recent studies have found a brain network linked to improvement in Parkinson's disease (PD) after deep brain stimulation (DBS), called the PD response network.
  • The study explored how noninvasive multifocal transcranial direct current stimulation (tDCS) affects motor symptoms in PD by targeting this network.
  • Results showed that active tDCS led to a significant reduction in PD symptoms compared to sham stimulation, suggesting noninvasive stimulation can effectively improve motor function in PD patients.
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  • * A study of 58 patients showed that different stimulation sites within STN are linked to specific improvements: cervical dystonia improved with stimulation of the ventral oral posterior nucleus, while limb dystonia and blepharospasm improved with dorsolateral STN stimulation.
  • * Each type of dystonia has distinct neural pathways and connectivity patterns, indicating that tailored stimulation targeting is essential for achieving the best treatment outcomes.
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  • Thalamic aphasia happens when certain parts of the thalamus get damaged, affecting how we understand and use language.
  • Researchers found that damage to specific thalamus areas is linked to difficulties with understanding and speaking, especially in the left side of the brain where important language areas are located.
  • The study highlights that these damaged areas in the thalamus are important for helping the brain's frontal regions, particularly Broca's area, to work properly when we talk or understand language.
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  • Deep Brain Stimulation (DBS) effectively improves symptoms of Parkinson's disease, including tremor, bradykinesia, rigidity, and axial symptoms, by stimulating specific white matter tracts.
  • A study involving 237 patients identified distinct brain tracts linked to improvements in each symptom, with tremor associated with the primary motor cortex and cerebellum, and axial symptoms linked to the supplementary motor cortex and brainstem.
  • An introduced algorithm utilizes these symptom-tract connections to tailor DBS settings for individual patients, aiming to enhance treatment effectiveness based on the most impactful symptoms for each person.
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Comprehensive understanding of the neural circuits involving the ventral tegmental area is essential for elucidating the anatomofunctional mechanisms governing human behaviour, in addition to the therapeutic and adverse effects of deep brain stimulation for neuropsychiatric diseases. Although the ventral tegmental area has been targeted successfully with deep brain stimulation for different neuropsychiatric diseases, the axonal connectivity of the region is not fully understood. Here, using fibre microdissections in human cadaveric hemispheres, population-based high-definition fibre tractography and previously reported deep brain stimulation hotspots, we find that the ventral tegmental area participates in an intricate network involving the serotonergic pontine nuclei, basal ganglia, limbic system, basal forebrain and prefrontal cortex, which is implicated in the treatment of obsessive-compulsive disorder, major depressive disorder, Alzheimer's disease, cluster headaches and aggressive behaviours.

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Diffusion-weighted MRI (dMRI) is a widely used neuroimaging modality that permits the in vivo exploration of white matter connections in the human brain. Normative structural connectomics - the application of large-scale, group-derived dMRI datasets to out-of-sample cohorts - have increasingly been leveraged to study the network correlates of focal brain interventions, insults, and other regions-of-interest (ROIs). Here, we provide a normative, whole-brain connectome in MNI space that enables researchers to interrogate fiber streamlines that are likely perturbed by given ROIs, even in the absence of subject-specific dMRI data.

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Introduction: White matter hyperintensities of presumed vascular origin (WMH) are associated with cognitive impairment and are a key imaging marker in evaluating cognitive health. However, WMH volume alone does not fully account for the extent of cognitive deficits and the mechanisms linking WMH to these deficits remain unclear. We propose that lesion network mapping (LNM), enables to infer if brain networks are connected to lesions, and could be a promising technique for enhancing our understanding of the role of WMH in cognitive disorders.

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  • * Researchers analyzed 14 cases of oculogyric crises and identified a shared neural network involved, which includes areas such as the basal ganglia, thalamus, brainstem, and cerebellum.
  • * The study found that this network correlates with gene expression for dopamine receptors, specifically DRD2, linking specific brain lesions to the occurrence of oculogyric crises due to D2 receptor blockage.
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The Deep Brain Stimulation (DBS) Think Tank XI was held on August 9-11, 2023 in Gainesville, Florida with the theme of "Pushing the Forefront of Neuromodulation". The keynote speaker was Dr. Nico Dosenbach from Washington University in St.

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Frontal circuits play a critical role in motor, cognitive and affective processing, and their dysfunction may result in a variety of brain disorders. However, exactly which frontal domains mediate which (dys)functions remains largely elusive. We studied 534 deep brain stimulation electrodes implanted to treat four different brain disorders.

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The advent of next-generation technology has significantly advanced the implementation and delivery of Deep Brain Stimulation (DBS) for Essential Tremor (ET), yet controversies persist regarding optimal targets and networks responsible for tremor genesis and suppression. This review consolidates key insights from anatomy, neurology, electrophysiology, and radiology to summarize the current state-of-the-art in DBS for ET. We explore the role of the thalamus in motor function and describe how differences in parcellations and nomenclature have shaped our understanding of the neuroanatomical substrates associated with optimal outcomes.

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  • Deep brain stimulation (DBS) is being explored as an effective treatment for severe obsessive-compulsive disorder (OCD), with various potential targets in the brain, especially around the anterior limb of the internal capsule and ventral striatum.
  • A study involving 82 OCD patients identified two key stimulation sites linked to significant symptom improvements: one near the anterior limb of the internal capsule and another near the inferior thalamic peduncle, while also showing that stimulation at certain locations can lead to better outcomes for depression and anxiety.
  • The findings suggest that refining the targeting of DBS could enhance treatment effectiveness and help optimize DBS programming for patients already receiving therapy.
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Deep-brain stimulation (DBS) is a potential novel treatment for memory dysfunction. Current attempts to enhance memory focus on stimulating human hippocampus or entorhinal cortex. However, an alternative strategy is to stimulate brain areas providing modulatory inputs to medial temporal memory-related structures, such as the nucleus accumbens (NAc), which is implicated in enhancing episodic memory encoding.

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Spatial normalization-the process of mapping subject brain images to an average template brain-has evolved over the last 20+ years into a reliable method that facilitates the comparison of brain imaging results across patients, centers & modalities. While overall successful, sometimes, this automatic process yields suboptimal results, especially when dealing with brains with extensive neurodegeneration and atrophy patterns, or when high accuracy in specific regions is needed. Here we introduce WarpDrive, a novel tool for manual refinements of image alignment after automated registration.

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Brain computer interfaces (BCI) provide unprecedented spatiotemporal precision that will enable significant expansion in how numerous brain disorders are treated. Decoding dynamic patient states from brain signals with machine learning is required to leverage this precision, but a standardized framework for identifying and advancing novel clinical BCI approaches does not exist. Here, we developed a platform that integrates brain signal decoding with connectomics and demonstrate its utility across 123 hours of invasively recorded brain data from 73 neurosurgical patients treated for movement disorders, depression and epilepsy.

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