Biology subjects

Mlinaric, T.

Publications and source records attributed to Mlinaric, T..

3 recordsLinked to original sources

bioRxiv2026

40 Hz visual stimulation increases gamma-band functional connectivity between visual, parietal and frontal regions

Visual stimulation at 40 Hz is being investigated as a non-invasive intervention for Alzheimer's disease. Its neural responses have been reported in regions beyond the visual cortex, and concurrent cognitive tasks have been shown to increase their spatial extent. However, it is unclear whether these responses reflect increased functional connectivity between regions or a common response to the stimulus, and whether a concurrent task changes this connectivity. We recorded EEG from 29 healthy young adults during Regular 40 Hz flicker and Irregular 30-50 Hz flicker, each with and without a target-counting task (2 x 2 within-participant design). Source-space connectivity between visual, parietal, and frontal regions was estimated with the debiased squared weighted phase-lag index (dWPLI). Regular stimulation increased 38-42 Hz connectivity for all three region pairs, with the largest increase between visual and parietal regions (increase in all 29 participants). The increase was specific to the stimulation frequency and was observed with two source reconstruction methods and in sensor space. The visual-parietal increase remained significant after correction for source leakage (spatial mixing between reconstructed sources) and after removal of the estimated stimulus-locked component, whereas the increases in visual-frontal and parietal-frontal connectivity did not. The concurrent task did not modulate the visual-parietal effect. For visual-frontal and parietal-frontal connectivity, the stimulation-by-ask interaction was not significant. These results show that 40 Hz visual stimulation increases gamma-band connectivity beyond the visual cortex, and much of this increase reflects a common stimulus-locked response, and connectivity beyond this response was observed mainly between visual and parietal regions.

neuroscience↗

bioRxiv2025

Peptide-induced hydration of lipid bilayers modulates packing pattern and conformations of hydrocarbon chains - a potential pathway for peptide translocation?

Cell-penetrating peptides (CPPs) with a cationic-hydrophobic character are recognized as carriers for delivering various therapeutics and diagnostic agents across cell membranes and into the cells. Among the most studied CPPs, nona-arginine (R9) exhibits superior penetration compared to nona-lysine (K9), suggesting that the penetration ability depends not only on charge, distribution and concentration of peptides but also on the lipid membrane composition. However, for heptapeptides composed of arginine (R), lysine (K) and phenylalanine (F) residues, which show some CPPs properties, these interactions remain unexplored. This study sheds light on the adsorption of R5F2/K5F2 on model prokaryotic (PRO) and eukaryotic (EU) lipid membranes containing a zwitterionic lipid (phosphatidylcholine; PC) and an anionic lipid (either phosphatidylglycerol, PG, in the PRO model, or phosphatidylserine, PS in EU) at the 90:10 molar ratio. Using differential scanning calorimetry (DSC) and temperature-dependent UV-Vis spectroscopy, we observed peptide-induced changes in the interfacial water layer that affect the fluidity and rigidity of lipid bilayers. The distinct adsorption behavior of R5F2/K5F2 on PRO and EU lipid bilayers revealed the changes in lipid packing and hydrocarbon chain conformations as exclusively peptide-dependent features. The peptide-induced formation of vacancies in the non-polar bilayer part is consistent with partial leakage observed in giant unilamellar vesicles. The synchronized arrangement could represent a mechanism for the concerted translocation of CPPs, along with their potential cargo across the lipid membrane. This study provides new insights into the peptide-lipid interactions underlying CPPs functionality.

biophysics↗

bioRxiv2024

Modulation of aperiodic EEG activity provides sensitive index of cognitive state changes during working memory task

To better understand cognitive processes, it is valuable to consider both periodic (oscillatory) and aperiodic electrophysiological brain activity. In this study, we aim to clarify how the periodic and aperiodic electrophysiological components respectively reflect the cognitive processes involved in working memory. Fifty-seven participants performed an n-back task while their brain activity was recorded using EEG. The analysis of both components of the EEG spectrum during task performance indicates that both periodic and aperiodic activities exhibit distinct task-related spatiotemporal dynamics that are closely related to cognitive demands. The results suggest that a substantial portion of the changes often attributed to theta oscillations in working memory tasks may be influenced by shifts in the spectral slope of aperiodic activity. This finding indicates that the modulation of aperiodic activity, associated with cognitive control processes, could provide a more sensitive index of cognitive state changes than previously recognised. To further confirm our findings, we also used these analysis methods in an item-recognition task, which showed similar patterns of periodic and aperiodic activity. These observations challenge the conventional understanding of low-frequency oscillations in cognitive processing and raise concerns about the routine practice of EEG baseline correction in time-frequency analysis, as it may obscure significant modulations in continuous working memory tasks. Consequently, the inclusion of aperiodic activity as a fundamental component of EEG analysis is likely to be critical for the accurate representation of the neural basis of cognition.

neuroscience↗