Biology subjects

Wendt, J.

Publications and source records attributed to Wendt, J..

4 recordsLinked to original sources

bioRxiv2025

Claustrum volume in human lifespan trajectory and effect of age, hemisphere, and sex

The human claustrum is a bilateral, thin, irregularly shaped gray matter structure located between the striatum and insula. While previous research demonstrated the effect of distinct medical conditions, such as prematurity, schizophrenia, and Alzheimers disease, on claustrum function and structure, it is poorly understood how non-pathologic biological conditions effect the claustrum. This study aimed to investigate the effect of age, hemisphere, and sex on claustrum volume. We used T1-weighted 3 Tesla MRI scans of 3,474 healthy participants ranging from 1 to 80 years of age, deep learning-based automated claustrum segmentation, and a normative modeling approach to delineate lifespan trajectories of claustrum volumes for both hemispheres and sexes. Additionally, ordinary least squares regression analyses were applied to further characterize age, hemisphere, and sex effect. Lifespan analysis revealed a trajectory of rapid claustrum volume increase from infancy to adolescence ([~] 1-15 years, annual growth 39.300 mm3/year), a plateau phase from early to middle adulthood ([~] 15-40 years, annual change 0.153 mm3/year), and a subsequent decline from middle adulthood to old age ([~] 40-80 years, annual decrease 10.325 mm3/year). The right claustrum was on average larger than the left one across all ages. Finally, overall, females had larger total intracranial volume-adjusted claustrum volumes than males across the lifespan. Results demonstrate a distinct effect of age, hemisphere, and sex on claustrum volume. Data provide a comprehensive framework for sex- and hemisphere-sensitive claustrum structure lifespan trajectories relevant for studying neurodevelopmental and neurodegenerative effects on the claustrum.

neuroscience↗

bioRxiv2021

New insights on the correspondence between subjective affective experience and physiological responses from representational similarity analyses

Classical views suggest that experienced affect is related to a specific bodily response (Fingerprint hypothesis), whereas recent perspectives challenge this view postulating that similar affective experiences rather evoke different physiological responses. To further advance this debate in the field, we used representational similarity analysis (N= 64) to investigate the correspondence between subjective affect (arousal and valence ratings) and physiological reactions (skin conductance response [SCR], startle blink response, heart rate and corrugator activity) across various emotion induction contexts (picture viewing task, sound listening task and imagery task). Significant similarities were exclusively observed between SCR and arousal in the picture viewing task. However, none of the other physiological measures showed a significant relation with valence and arousal ratings in any of the tasks. These findings tend to support the populations hypothesis, suggesting that there is no clear match between the evoked physiological responses and the experienced subjective affect between individuals. Statement of relevanceThe subjective affective experience evoked by an event is accompanied by physiological responses. The correspondence between physiological response patterns and the experienced affect, however, is still under debate. Classical views (Fingerprint hypothesis) suggest that affect is related to a specific physiological response, whereas recent perspectives (Populations hypothesis) challenge this view, postulating rather different physiological responses. In the current study, we used representational similarity analysis (RSA) to examine the relation between affective experience, assessed using valence and arousal ratings, and the evoked physiological reactivity across three affect-inducing contexts. Results showed significant similarities exclusively between SCR and arousal in the passive picture viewing task. However, none of the other physiological measures showed a significant relation with valence and arousal ratings in any of the tasks, supporting the populations hypothesis. These findings invite to reframe the relation between physiology and affect from invariant and homogeneous to variant and context-dependent.

neuroscience↗

bioRxiv2019

The neurofunctional basis of affective startle modulation in humans - evidence from combined facial EMG-fMRI

The startle reflex, a protective response elicited by an immediate, unexpected sensory event, is potentiated when evoked during threat and inhibited during safety. In contrast to skin conductance responses or pupil dilation, modulation of the startle reflex is valence-specific and considered the cross-species translational tool for defensive responding.\n\nRodent models implicate a modulatory pathway centering on the brainstem (i.e., nucleus reticularis pontis caudalis, PnC) and the centromedial amygdala (CeM) as key hubs for flexibly integrating valence information into differential startle magnitude.\n\nWe employed innovative combined EMG-fMRI measurements in two independent experiments and samples and provide converging evidence for the involvement of these key regions in the modulatory acoustic startle reflex pathway in humans. Furthermore, we provide the crucial direct link between EMG startle eye-blink magnitude and neural response strength.\n\nWe argue that startle-evoked amygdala responding and its affective modulation may hold promise as an important novel tool for affective neuroscience.

neuroscience↗

bioRxiv2019

CO2 conversion to methane and biomass in obligate methylotrophic methanogens in marine sediments

Methyl substrates are important compounds for methanogenesis in marine sediments but diversity and carbon utilization by methylotrophic methanogenic archaea have not been clarified. Here, we demonstrate that RNA-stable isotope probing (SIP) requires 13C-labeled bicarbonate as co-substrate for identification of methylotrophic methanogens in sediment samples of the Helgoland mud area, North Sea. Using lipid-SIP, we found that methylotrophic methanogens incorporate 60 to 86% of dissolved inorganic carbon (DIC) into lipids, and thus considerably more than what can be predicted from known metabolic pathways ([~]40% contribution). In slurry experiments amended with the marine methylotroph Methanococcoides methylutens, up to 12% of methane was produced from CO2, indicating that CO2-dependent methanogenesis is an alternative methanogenic pathway and suggesting that obligate methylotrophic methanogens grow in fact mixotrophically on methyl compounds and DIC. Thus, the observed high DIC incorporation into lipds is likely linked to CO2-dependent methanogenesis, which was triggered when methane production rates were low. Since methylotrophic methanogenesis rates are much lower in marine sediments than under optimal conditions in pure culture, CO2 conversion to methane is an important but previously overlooked methanogenic process in sediments for methylotrophic methanogens.

microbiology↗