Biology subjects

Benoit, E.

Publications and source records attributed to Benoit, E..

3 recordsLinked to original sources

bioRxiv2023

Noradrenergic Tone is Not Required for Neuronal Activity-Induced Rebound Sleep in Zebrafish

Sleep pressure builds during wakefulness, but the mechanisms underlying this homeostatic process are poorly understood. One zebrafish model suggests that sleep pressure increases as a function of global neuronal activity, such as during sleep deprivation or acute exposure to drugs that induce widespread brain activation. Given that the arousal-promoting noradrenergic system is important for maintaining heightened neuronal activity during wakefulness, we hypothesised that genetic and pharmacological reduction of noradrenergic tone during drug-induced neuronal activation would dampen subsequent rebound sleep in zebrafish larvae. Unexpectedly, dampening noradrenergic tone with the 2-adrenoceptor agonist clonidine during acute caffeine or pentylenetetrazol treatment enhanced subsequent rebound sleep, while stimulating noradrenergic signalling during caffeine exposure with a cocktail of 1- and {beta}-adrenoceptor agonists did not enhance sleep. Similarly, CRISPR/Cas9-mediated elimination of the dopamine {beta}-hydroxylase (dbh) gene, which encodes an enzyme required for noradrenalin synthesis, enhanced baseline sleep in larvae but did not prevent additional rebound sleep following acute induction of neuronal activity. Across all drug conditions, c-fos expression immediately after drug exposure varied inversely with noradrenergic tone and correlated strongly with the amount of induced rebound sleep. These results are consistent with a model in which increases in neuronal activity, as reflected by brain-wide levels of c-fos induction, drive a sleep pressure signal that promotes rebound sleep independently of noradrenergic tone.

neuroscience↗

bioRxiv2020

Full-field optical coherence tomography for the diagnosis of giant cell arteritis

Histopathological examination of temporal artery biopsy (TAB) remains the gold standard for the diagnosis of giant cell arteritis (GCA) but is associated with essential limitations that emphasize the need for an upgraded pathological process. This study pioneered the use of full-field optical coherence tomography (FF-OCT) for rapid and automated on-site pathological diagnosis of GCA. Sixteen TABs (12 negative and 4 positive for GCA) were selected according to major histopathological criteria of GCA following hematoxylin-eosin-saffron-staining for subsequent acquisition with FF-OCT to compare structural modifications of the artery cell wall and thickness of each tunica. Gabor filtering of FF-OCT images was then used to compute TAB orientation maps and validate a potential automated analysis of TAB sections. FF-OCT allowed both qualitative and quantitative visualization of the main structures of the temporal artery wall, from the internal elastic lamina to the vasa vasorum and red blood cells, unveiling a significant correlation with conventional histology. FF-OCT imaging of GCA TABs revealed destruction of the media with distinct remodeling of the whole arterial wall into a denser reticular fibrous neo-intima, which is distinctive of GCA pathogenesis and accessible through automated Gabor filtering. Rapid on-site FF-OCT TAB acquisition makes it possible to identify some characteristic pathological lesions of GCA within a few minutes, paving the way for potential machine intelligence-based or even non-invasive diagnosis of GCA.View Full Text

pathology↗

bioRxiv2019

Null results from a dimensional study of error-related negativity (ERN) and self-reported psychiatric symptoms

Alterations in error processing are implicated in a range of DSM-defined psychiatric disorders. For instance, obsessive-compulsive disorder (OCD) and generalised anxiety disorder show enhanced electrophysiological responses to errors - i.e. error-related negativity (ERN) - while others like schizophrenia have an attenuated ERN. However, as diagnostic categories in psychiatry are heterogeneous and also highly intercorrelated, the precise mapping of ERN enhancements and impairments is unclear. To address this, we recorded electroencephalograms (EEG) from 196 participants who performed the Flanker task and collected scores on 9 questionnaires assessing psychiatric symptoms to test if a dimensional framework could reveal specific transdiagnostic clinical manifestations of error processing dysfunctions. Contrary to our hypothesis, we found no association between ERN amplitude and symptom severity of OCD, trait anxiety, depression, social anxiety, impulsivity, eating disorders, alcohol addiction, schizotypy or apathy. A transdiagnostic approach did nothing to improve signal; there was no association between three transdiagnostic dimensions (anxious-depression, compulsive behaviour and intrusive thought and social withdrawal) and ERN magnitude. In these same individuals, we replicated a previously published transdiagnostic association between goal-directed learning and compulsive behaviour and intrusive thought. Associations between the ERN and psychopathology might be smaller than previously assumed and/or dependent on a greater level of symptom severity than other transdiagnostic cognitive biomarkers.

neuroscience↗