Roger Luechinger

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Luechinger

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Roger

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0000-0002-7365-0421

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Publications 1 - 10 of 21

Detecting analogies unconsciously
Reber, Thomas P.; Luechinger, Roger; Bösiger, Peter; et al. (2014)
Frontiers in Behavioral Neuroscience
Analogies may arise from the conscious detection of similarities between a present and a past situation. In this functional magnetic resonance imaging study, we tested whether young volunteers would detect analogies unconsciously between a current supraliminal (visible) and a past subliminal (invisible) situation. The subliminal encoding of the past situation precludes awareness of analogy detection in the current situation. First, participants encoded subliminal pairs of unrelated words in either one or nine encoding trials. Later, they judged the semantic fit of supraliminally presented new words that either retained a previously encoded semantic relation (“analog”) or not (“broken analog”). Words in analogs versus broken analogs were judged closer semantically, which indicates unconscious analogy detection. Hippocampal activity associated with subliminal encoding correlated with the behavioral measure of unconscious analogy detection. Analogs versus broken analogs were processed with reduced prefrontal but enhanced medial temporal activity. We conclude that analogous episodes can be detected even unconsciously drawing on the episodic memory network.
Feeling at home in a virtually amputated body; neural and phenomenological effects of illusory embodiment in body integrity dysphoria
Saetta, Gianluca; Peter, Yannik; Ruddy, Kathy; et al. (2025)
Journal of Psychiatric Research
In Body Integrity Dysphoria (BID) a profound incongruity between the physical body and the desired, i.e., amputated body, often leads to a desire for limb amputation. Virtual reality (VR) and multisensory stimulation paradigms provide powerful tools to create the experience of being embodied in an amputated body. Here we investigate the impact of such an experience on neural and subjective responses in 18 individuals with BID and 18 controls. We used both task-based and resting-state MRI before and after participants played an immersive virtual game in an amputated body corresponding to their desired bodily shape and mimicking their movements. The task-based fMRI assessed neural activity when viewing images of the body in the desired versus the undesired state. Individuals with BID reported higher sense of ownership and control over the virtual body. Task-based fMRI showed increased pre-VR activity in the right superior parietal lobule (rSPL), right angular gyrus, and right supplementary motor area in the BID group, normalizing after VR exposure. Resting-state fMRI showed reduced connectivity in the rSPL, visuo-occipital areas, fronto-parietal, and fronto-striatal mirror and limb system networks, also normalizing post-VR. Additionally, there was a normalization in the pattern of increased connectivity of cortico-striatal tracts connecting the rSPL and the pars orbitalis of the right inferior frontal gyrus with the nucleus accumbens. Our findings suggest that virtual embodiment effectively modulates BID-related neural networks, offering a safe, cost-effective intervention for BID and highlights VR's potential in exploring the complex interaction between body and self, with potential implications for similar psychiatric conditions.
Intrinsic brain connectivity alterations despite intact pain inhibition in subjects with neuropathic pain after spinal cord injury: a pilot study
Huynh, Vincent; Lütolf, Robin; Rosner, Jan; et al. (2023)
Scientific Reports
Endogenous pain modulation in humans is frequently investigated with conditioned pain modulation (CPM). Deficient pain inhibition is a proposed mechanism that contributes to neuropathic pain (NP) after spinal cord injury (SCI). Recent studies have combined CPM testing and neuroimaging to reveal neural correlates of CPM efficiency in chronic pain. This study investigated differences in CPM efficiency in relation to resting-state functional connectivity (rsFC) between 12 SCI-NP subjects and 13 age- and sex-matched healthy controls (HC). Twelve and 11 SCI-NP subjects were included in psychophysical and rsFC analyses, respectively. All HC were included in the final analyses. Psychophysical readouts were analysed to determine CPM efficiency within and between cohorts. Group differences of rsFC, in relation to CPM efficiency, were explored with seed-to-voxel rsFC analyses with pain modulatory regions, e.g. ventrolateral periaqueductal gray (vlPAG) and amygdala. Overall, pain inhibition was not deficient in SCI-NP subjects and was greater in those with more intense NP. Greater pain inhibition was associated with weaker rsFC between the vlPAG and amygdala with the visual and frontal cortex, respectively, in SCI-NP subjects but with stronger rsFC in HC. Taken together, SCI-NP subjects present with intact pain inhibition, but can be differentiated from HC by an inverse relationship between CPM efficiency and intrinsic connectivity of supraspinal regions. Future studies with larger cohorts are necessary to consolidate the findings in this study.
Safety, feasibility, and diagnostic value of cardiac magnetic resonance imaging in patients with cardiac pacemakers and implantable cardioverters/defibrillators at 1.5 T
Naehle, Claas P.; Kreuz, Jens; Strach, Katharina; et al. (2011)
American Heart Journal
Background Recent studies suggest that magnetic resonance (MR) imaging of the brain and spine may safely be performed in patients with pacemakers (PMs) and implantable cardioverter/defibrillators (ICDs), when taking adequate precautions. The aim of this study was to investigate safety, feasibility, and diagnostic value (DV) of MR imaging in cardiac applications (cardiac MR [CMR]) in patients with PMs and ICDs for the first time. Methods Thirty-two PM/ICD patients with a clinical need for CMR were examined. The specific absorption rate was limited to 1.5 W/kg. Devices were reprogrammed pre-CMR to minimize interference with the electromagnetic fields. Devices were interrogated pre-CMR and post-CMR and after 3 months. Troponin I levels were measured pre-CMR and post-CMR; image quality (IQ) and DV of CMR were assessed. Results All devices could be reprogrammed normally post-CMR. No significant changes of pacing capture threshold, lead impedance, and troponin I were observed. Image quality in patients with right-sided devices (RSD) was better compared with that in patients with left-sided devices (LSD) (P < .05), and less myocardial segments were affected by device-related artefacts (P < .05). Diagnostic value was rated as sufficiently high, allowing for diagnosis, or better in 12 (100%) of 12 patients with RSD, and only in 7 (35%) of 20 patients with LSD. Conclusions Cardiac MR may be performed safely when limiting specific absorption rate, appropriately monitoring patients, and following device reprogramming. Cardiac MR delivers good IQ and DV in patients with RSD. Cardiac MR in patients with RSD may therefore be performed with an acceptable risk/benefit ratio, whereas the risk/benefit ratio is rather unfavorable in patients with LSD.
Descending pain modulatory efficiency in healthy subjects is related to structure and resting connectivity of brain regions
Huynh, Vincent; Lütolf, Robin; Rosner, Jan; et al. (2022)
NeuroImage
The descending pain modulatory system in humans is commonly investigated using conditioned pain modulation (CPM). Whilst variability in CPM efficiency, i.e., inhibition and facilitation, is normal in healthy subjects, exploring the inter-relationship between brain structure, resting-state functional connectivity (rsFC) and CPM readouts will provide greater insight into the underlying CPM efficiency seen in healthy individuals. Thus, this study combined CPM testing, voxel-based morphometry (VBM) and rsFC to identify the neural correlates of CPM in a cohort of healthy subjects (n =40), displaying pain inhibition (n = 29), facilitation (n = 10) and no CPM effect (n = 1). Clusters identified in the VBM analysis were implemented in the rsFC analysis alongside key constituents of the endogenous pain modulatory system. Greater pain inhibition was related to higher volume of left frontal cortices and stronger rsFC between the motor cortex and periaqueductal grey. Conversely, weaker pain inhibition was related to higher volume of the right frontal cortex - coupled with stronger rsFC to the primary somatosensory cortex, and rsFC between the amygdala and posterior insula. Overall, healthy subjects showed higher volume and stronger rsFC of brain regions involved with descending modulation, while the lateral and medial pain systems were related to greater pain inhibition and facilitation during CPM, respectively. These findings reveal structural alignments and functional interactions between supraspinal areas involved in CPM efficiency. Ultimately understanding these underlying variations and how they may become affected in chronic pain conditions, will advance a more targeted subgrouping in pain patients for future cross-sectional studies investigating endogenous pain modulation.
Ramping down a clinical 3 T scanner: a journey into MRI and MRS at 0.75 T
Guenthner, Christian; Peereboom, Sophie Marie; Dillinger, Hannes; et al. (2023)
Magnetic Resonance Materials in Physics, Biology, and Medicine
ObjectLower-field MR is reemerging as a viable, potentially cost-effective alternative to high-field MR, thanks to advances in hardware, sequence design, and reconstruction over the past decades. Evaluation of lower field strengths, however, is limited by the availability of lower-field systems on the market and their considerable procurement costs. In this work, we demonstrate a low-cost, temporary alternative to purchasing a dedicated lower-field MR system.Materials and MethodsBy ramping down an existing clinical 3 T MRI system to 0.75 T, proton signals can be acquired using repurposed C-13 transmit/receive hardware and the multi-nuclei spectrometer interface. We describe the ramp-down procedure and necessary software and hardware changes to the system.ResultsApart from presenting system characterization results, we show in vivo examples of cardiac cine imaging, abdominal two- and three-point Dixon-type water/fat separation, water/fat-separated MR Fingerprinting, and point-resolved spectroscopy. In addition, the ramp-down approach allows unique comparisons of, e.g., gradient fidelity of the same MR system operated at different field strengths using the same receive chain, gradient coils, and amplifiers.DiscussionRamping down an existing MR system may be seen as a viable alternative for lower-field MR research in groups that already own multi-nuclei hardware and can also serve as a testing platform for custom-made multi-nuclei transmit/receive coils.
A MR Imaging Procedure to Measure Tarsal Bone Rotations
Wolf, Peter; Luechinger, Roger; Bösiger, Peter; et al. (2007)
Journal of Biomechanical Engineering
Magnetic resonance imaging offers unique insights into three-dimensional foot bone motion. Thereby, adequate devices enabling defined loading and positioning of the foot are needed to profit from this noninvasive procedure. Tarsal bone positions of three healthy subjects were repeatedly measured in a pronated and a supinated foot excursion under bodyweight with a newly developed MR imaging procedure. The quantification of the transferred motion from the loading and positioning device to the calcaneus and an estimation of the required degrees to distinguish between tarsal joint rotations were used to evaluate the applicability of the procedure to investigate tarsal joint motion. It was found that 45–70% (75–95%) of the externally applied 15deg foot pronation (supination) were transferred to the calcaneus. Furthermore, the talonavicular joint showed the largest amount of rotation up to 20deg eversion-inversion and abadduction, followed by the subtalar joint showing nearly half of that motion. Considerably less motion was found between the cuboid and calcaneus (about 2–6deg) and the cuboid nearly did not rotate relative to the navicular (on average 1deg). The estimated necessary differences between tarsal joint movements to identify individual kinematic behavior were in the order of 2deg (4deg related to the talonavicular joint). Since the results were in agreement with the literature, it is concluded that the applicability of the presented procedure to investigate tarsal bone mechanics is warranted. The possibility to evaluate 3D tarsal joint motion in combination with bone morphology (e.g., joint curvature) may provide new insights in the still uncertain relationship between foot function and foot morphology.
A genome-wide survey and functional brain imaging study identify CTNNBL1 as a memory-related gene
Papassotiropoulos, Andreas; Stefanova, Elka D.; Vogler, Christian; et al. (2013)
Molecular Psychiatry
Unbiased genome-wide screens combined with imaging data on brain function may identify novel molecular pathways related to human cognition. Here we performed a dense genome-wide screen to identify episodic memory-related gene variants. A genomic locus encoding the brain-expressed beta-catenin-like protein 1 (CTNNBL1) was significantly (P=7 × 10−8) associated with verbal memory performance in a cognitively healthy cohort from Switzerland (n=1073) and was replicated in a second cohort from Serbia (n=524; P=0.003). Gene expression studies showed CTNNBL1 genotype-dependent differences in beta-catenin-like protein 1 mRNA levels in the human cortex. Functional magnetic resonance imaging in 322 subjects detected CTNNBL1 genotype-dependent differences in memory-related brain activations. Converging evidence from independent experiments and different methodological approaches suggests a role for CTNNBL1 in human memory.
Material-Dependent Implant Artifact Reduction Using SEMAC-VAT and MAVRIC: A Prospective MRI Phantom Study
Filli, Lukas; Jud, Lukas; Luechinger, Roger; et al. (2017)
Investigative Radiology
Safety of magnetic resonance imaging of patients with a new Medtronic EnRhythm MRI SureScan pacing system: clinical study design
Sutton, Richard; Kanal, Emanuel; Wilkoff, Bruce L.; et al. (2008)
Trials
Background Magnetic Resonance Imaging (MRI) of patients with implanted cardiac devices is currently considered hazardous due to potential for electromagnetic interference to the patient and pacemaker system. With approximately 60 million MRI scans performed worldwide per year, an estimated majority of pacemaker patients may develop an indication for an MRI during the lifetime of their pacemakers, suggesting that safe use of pacemakers in the MRI environment would be clinically valuable. A new pacing system (Medtronic EnRhythm MRI™ SureScan™ and CapSureFix MRI™ leads) has been designed and pre-clinically tested for safe use in the MRI environment. The EnRhythm MRI study is designed to confirm the safety and efficacy of this new pacing system. Methods The EnRhythm MRI study is a prospective, randomized controlled, unblinded clinical trial to confirm the safety and efficacy of MRI at 1.5 Tesla in patients implanted with a specifically designed pacemaker and lead system. The patients have standard indications for dual chamber pacemaker implantation. Successfully implanted patients are randomized in a 2:1 ratio to undergo MRI (MRI group) or to have no MRI scan (control group) at 9–12 weeks after pacemaker system implantation. Magnetic resonance (MR) scanning includes 14 head and lumbar scan sequences representing clinically relevant scans while maximizing the gradient slew rate up to 200 T/m/s, and/or the transmitted radiofrequency (RF) power up to SAR (specific absorption rate) levels of 2 W/kg body weight (upper limit of normal operating mode). Full interrogation of all device information and sensing and capture function are measured at device implantation, every follow-up and before and immediately after MRI in the MRI group and at the same time points in the control group. Complete pacemaker and lead evaluations are also done at one week and one month after the scan for the MRI and control group patients. The primary endpoint is safe and successful completion of the MRI scan as measured by freedom from both MRI-procedure related complications and clinically significant changes in the sensing and capture function of the leads. Results Results will be communicated after approximately 156 and 470 patients have completed 4 months of follow-up.

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