Biology subjects

Griessenauer, C.

Publications and source records attributed to Griessenauer, C..

2 recordsLinked to original sources

bioRxiv2025

MEP-independent silent periods in hand muscles elicited by Transcranial Magnetic Stimulation of the ventral premotor cortex: a non-invasive tool to explore premotor negative motor areas

ObjectiveWe investigate the possibility to disrupt motor activity via premotor and parietal cortex stimulation, by inducing cortical silent periods (cSPs) in the voluntarily activated upper limb. MethodsWe analyzed data from 17 subjects with normal brain function, using navigated TMS (nTMS) on individual MR anatomies. We applied single-pulse biphasic stimulation at 120% of resting motor threshold (rMT) in blocks of 30 stimulations on each spot of a 10-16 point grid covering the inferior parietal and frontal lobes in the dominant hemisphere while participants performed voluntary submaximal contraction. Electromyography (EMG) was recorded bilaterally from intrinsic hand muscles. ResultsWe observed cSPs not preceded by a MEP in the contralateral hand in 16/17 participants. The maximum overlap, of individual areas where such MEP-independent cSPs could be evoked, corresponded to the ventral precentral gyrus (MNI coordinates: [x=-57, y=7, z=33]). In a subset of stimulus sites, MEP-independent cSPs were bilateral, with contralateral predominance. Canonical short-latency MEPs were observed in all patients, with maximum overlap over the primary motor cortex. We also observed rare contralateral long-latency (> 23 ms) MEP-like responses from peri-Rolandic TMS. ConclusionsMEP-independent cSPs are systematically elicitable in healthy participants They likely reflect interference with premotor representations of ongoing movements. They offer a novel possibility to investigate higher-order motor functions in the experimental and clinical neurosciences.

neuroscience↗

bioRxiv2020

Sex-specific lesion topographies explain outcomesafter acute ischemic stroke

Acute ischemic stroke affects men and women differently in many ways. In particular, women are oftentimes reported to experience a higher acute stroke severity than men. Here, we derived a low-dimensional representation of anatomical stroke lesions and designed a sex-aware Bayesian hierarchical modelling framework for a large-scale, well phenotyped stroke cohort. This framework was tailored to carefully estimate possible sex differences in lesion patterns explaining acute stroke severity (NIHSS) in 1,058 patients (39% female). Anatomical regions known to subserve motor and language functions emerged as relevant regions for both men and women. Female patients, however, presented a more widespread pattern of stroke severity-relevant lesions than male patients. Furthermore, particularly lesions in the posterior circulation of the left hemisphere underlay a higher stroke severity exclusively in women. These sex-sensitive lesion pattern effects could be discovered and subsequently robustly replicated in two large independent, multisite lesion datasets. The constellation of findings has several important conceptual and clinical implications: 1) suggesting sex-specific functional cerebral asymmetries, and 2) motivating a sex-stratified approach to management of acute ischemic stroke. To go beyond sex-averaged stroke research, future studies should explicitly test whether acute therapies administered on the basis of sex-specific cutoff volumes of salvageable tissue will lead to improved outcomes in women after acute ischemic stroke.

neuroscience↗