Biology subjects

Boehm, C.

Publications and source records attributed to Boehm, C..

5 recordsLinked to original sources

bioRxiv2026

Chronic stress does not induce behavioural signs of tinnitus or cochlear synaptopathy in Mongolian gerbils

Tinnitus is commonly associated with psychosocial stress. However, it is unclear whether stress alone is sufficient to induce neural alterations resulting in tinnitus. In this study, we investigated the causal role of stress in tinnitus generation by experimentally isolating stress exposure as the sole independent variable in a well-established Mongolian gerbil model. Animals were subjected to repeated, inescapable electric foot shocks over three weeks to create a chronic, repeated stress paradigm. Behavioural, endocrine and histological measures were combined to assess tinnitus perception, stress system activation and cochlear synaptopathy. Repeated stress exposure reliably activated the endocrine stress response, as indicated by transient increases in serum cortisol following specific stress sessions. Basal cortisol levels returned to baseline values after the stress period. Behavioural assessment using gap-prepulse inhibition of the acoustic startle reflex revealed only isolated cases of behavioural signs of tinnitus, which occurred at a frequency consistent with false-positive detection and were evenly distributed between stress-exposed and control animals. Histological analyses revealed that ribbon synapse counts were preserved across the cochlea, with no evidence of stress-induced synaptopathy. No systematic relationships were observed between endocrine activation, behavioural outcomes and the number of inner hair cell ribbon synapses. Taken together, these findings suggest that, in the absence of acoustic trauma, repeated chronic stress is not sufficient to induce tinnitus or inner hair cell synaptopathy. These results argue against a primary causal role of stress alone in tinnitus generation and instead support models in which stress modulates symptom expression or perceptual salience in the context of pre-existing auditory dysfunction.

neuroscience↗

bioRxiv2025

Miniaturized Device for Assessing Calcification Propensity of Biohybrid Implants Under Continuous Flow

Biohybrid implants are a promising development for cardiovascular disease treatment but suffer from problems like thrombogenesis and calcification. However, testing and validating biohybrid implants can be difficult and expensive due to material handling, fabrication methods and specialty medium components. The devices used to test potential samples can be large and expensive, requiring significant amounts of cell culture medium to operate. Additional, conventional static cell culture conditions do not accurately represent the vascular environment as shear and mechanical forces play key roles in the development of calcification. To address these challenges, a miniaturized, dual-channel flow chamber was designed and validated that allowed for real-time visualization of biohybrid calcification in a physiological environment. Computational Fluid Dynamics simulations were performed to determine the flow characteristics that generated physiological shear stress homogeneously across the sample surface. Micro particle tracking velocimetry measurements validated the simulated shear stresses near the sample surface. Two implant materials used for biohybrid construction, bovine pericardium and polycarbonate urethane, were inserted in the device and exposed to a flowing calcification medium for 14 days. Fluorescent fetuin-A was introduced into the calcification medium for real-time calcification monitoring. The two materials were compared with matched samples calcified in a large fatigue tester for 14 days. Our results showed similar material calcification for bovine pericardium and no calcification for polycarbonate urethane in the large fatigue tester and in our newly developed device. Biohybrid textile-reinforced fibrin-based scaffold populated with vascular smooth muscle cells started to calcify over 7 days in calcification medium. We conclude that this platform will provide novel insights into the origin and progression of pathological calcification and its potentially harmful health effects, which can occur as a result of tissue or metabolic abnormalities, disease, or implantation of certain biomaterials, by providing the ability to monitor the progression of calcification in biohybrid implants in real time, while also minimizing the cost and size of samples and reagents required for testing.

bioengineering↗

bioRxiv2024

varVAMP: automated pan-specific primer design for tiled full genome sequencing and qPCR of highly diverse viral pathogens.

Time- and cost-saving surveillance of viral pathogens is achieved by tiled sequencing in which a viral genome is amplified in overlapping PCR amplicons and qPCR. However, designing pan-specific primers for viral pathogens that have high genomic variability represents a major challenge. Here, we present a bioinformatics command-line tool, called varVAMP (variable virus amplicons). It relies on multiple sequence alignments of highly variable virus sequences and enables automatic pan-specific primer design for qPCR or tiled amplicon whole genome sequencing. The varVAMP software guarantees pan-specificity by two means: it designs primers in regions with minimal variability and introduces degenerate nucleotides into primer sequences to compensate for common sequence variations. We demonstrate varVAMPs utility by designing and evaluating novel pan-specific primer schemes suitable for sequencing the genomes of SARS-CoV-2, Hepatitis E virus, rat Hepatitis E virus, Hepatitis A virus, Borna-disease-virus-1, and Poliovirus. Moreover, we established highly sensitive and specific Poliovirus qPCR assays that could potentially simplify current Poliovirus surveillance. Importantly, wet-lab and bioinformatic techniques established for SARS-CoV-2 tiled amplicon sequencing were readily transferable to these new primer schemes and will allow sequencing laboratories to extend their established methodology to other human pathogens.

bioinformatics↗

bioRxiv2022

Deep learning based decoding of local field potential events

How is information processed in the cerebral cortex? To answer this question a lot of effort has been undertaken to create novel and to further develop existing neuroimaging techniques. Thus, a high spatial resolution of fMRI devices was the key to exactly localize cognitive processes. Furthermore, an increase in time-resolution and number of recording channels of electro-physiological setups has opened the door to investigate the exact timing of neural activity. However, in most cases the recorded signal is averaged over many (stimulus) repetitions, which erases the fine-structure of the neural signal. Here, we show that an unsupervised machine learning approach can be used to extract meaningful information from electro-physiological recordings on a single-trial base. We use an auto-encoder network to reduce the dimensions of single local field potential (LFP) events to create interpretable clusters of different neural activity patterns. Strikingly, certain LFP shapes correspond to latency differences in different recording channels. Hence, LFP shapes can be used to determine the direction of information flux in the cerebral cortex. Furthermore, after clustering, we decoded the cluster centroids to reverse-engineer the underlying prototypical LFP event shapes. To evaluate our approach, we applied it to both neural extra-cellular recordings in rodents, and intra-cranial EEG recordings in humans. Finally, we find that single channel LFP event shapes during spontaneous activity sample from the realm of possible stimulus evoked event shapes. A finding which so far has only been demonstrated for multi-channel population coding.

neuroscience↗

bioRxiv2022

Neural Correlates of Linguistic Collocations During Continuous Speech Perception

Language is fundamentally predictable, both on a higher schematic level as well as low-level lexical items. Regarding predictability on a lexical level, collocations are frequent co-occurrences of words that are often characterized by high strength of association. So far, psycho-and neurolin guistic studies have mostly employed highly artificial experimental paradigms in the investigation of collocations by focusing on the processing of single words or isolated sentences. In contrast, here we analyze EEG brain responses recorded during stimulation with continuous speech, i.e. audio books. We find that the N400 response to collocations is significantly different from that of non-collocations, whereas the effect varies with respect to cortical region (anterior/ posterior) and laterality (left/right). Our results are in line with studies using continuous speech, and they mostly contradict those using artificial paradigms and stimuli. To the best of our knowledge, this is the first neurolinguistic study on collocations using continuous speech stimulation.

neuroscience↗