Biology subjects

Soltani, S.

Publications and source records attributed to Soltani, S..

2 recordsLinked to original sources

bioRxiv2023

The Induced Fatigue on Attention Networks of Active and Inactive Individuals Effect of Exercise

BackgroundThe relationship between physical activity and cognitive functions is well established, with regular exercise improving cognitive functions. However, there is less clarity surrounding the effect of exercise-induced fatigue on attention network particularly in those with a history of continuous physical activity. AimsThis research was aimed to determine whether exercise-induced fatigue can affect cognitive functions, especially those involved in attentional control (i.e., alerting, orientation, and executive functions) and to identify any differences in attentional control between active and inactive individuals after exercise-induced fatigue. MethodsWe compared the performance of 24 physically active and inactive participants in the Attentional Network Task, which allows for the assessment of the executive, orienting and alerting networks. Under two conditions regarding exercise-induced fatigue (pre-fatigue and post-fatigue), we used sub-maximum aerobic endurance training to induce fatigue to the exhaustion point. ResultsThe results showed that fatiguing exercise improved alertness in both groups; however, the executive control network of the active group improved while the orienting and executive control networks of the inactive group performed worse. ConclusionsDepending on the participants degree of physical activity and the particular task used to test each of these attention networks, exercise-induced exhaustion had a different impact on different attention networks.

neuroscience↗

bioRxiv2021

Free energy and stacking of eumelaninnanoaggregates

Eumelanin, a member of the melanin family, is a black-brown insoluble pigment. It possesses a broad range of properties such as antioxidation, free radical scavenging, photo-protection, and charge carrier transportation. Surprisingly, the exact molecular structure of eumelanin remains undefined. It is, however, generally considered to consist of two main building blocks, 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole carboxylic acid (DHICA). We focus on DHI and report, for the first time, a computational investigation of structural properties of DHI eumelanin aggregates in aqueous solutions. First, multi-microsecond molecular dynamics (MD) simulations at different concentrations were performed to investigate aggregation and ordering of tetrameric DHI-eumelanin protomolecules. This was followed by umbrella sampling (US) and density functional theory (DFT) calculations to study the physical mechanisms of stacking. Aggregation occurs through formation of nanoscale stacks and was observed in all systems. Further analyses showed that aggregation and coarsening of the domains is due to decrease in hydrogen bonds between the eumelanins and water; while domains exist, there is no long-range order. The results show non-covalent stacks with and interlayer distance between eumelanin protomolecules being less than 3.5 [A]. This is in good agreement with transmission electron microscopy data. Both free energy calculations and DFT revealed strong stacking interactions. The electrostatic potential map provides an explanation and a rationale for the slightly sheared relative orientations and, consequently, for the curved shapes of the nanoscale domains.

biophysics↗