Biology subjects

Soltani, S.

Publications and source records attributed to Soltani, S..

4 recordsLinked to original sources

bioRxiv2025

Risky Choices After Frontal Brain Injury: Differential Effects in Self vs Other-Decision Contexts

Frontal lobe integrity is crucial for assessing risk and making informed decisions. This study investigated how frontal lobe lesions affect the computational mechanisms underlying risky choice, particularly when decisions impact oneself versus another person. A Patient Group of 20 individuals with frontal cortex damage and a Control Group of 20 matched individuals performed a gambling task, making accept/reject decisions on mixed-outcome gambles for themselves ("Self") or an anonymous other ("Other"). We provide a mechanistic account of choice behavior using Prospect Theory, the leading behavioral model of decision-making under risk, to quantify parameters for utility curvature, loss aversion, and probability weighting. Behaviorally, the Patient Group accepted significantly more disadvantageous gambles for themselves than did the Control Group yet showed a trend toward greater caution when choosing for others. Prospect Theory modeling revealed a specific computational phenotype for this behavior. Compared to the Control Group, the Patient Group exhibited significantly more pronounced utility curvature (lower , {beta}) and more linear, less distorted probability weighting (higher {gamma}). While patients also showed a trend toward lower loss aversion ({lambda}), this difference was not statistically significant. This combination of altered utility and probability processing explains their paradoxical risk-seeking. These findings suggest that frontal cortex damage disrupts the computation of subjective value, leading to a distinctive decision-making profile marked by altered utility curvature and reduced sensitivity to outcome magnitudes. This computational characterization deepens our understanding of frontal lobe contributions to decision-making and can inform targeted rehabilitation strategies.

neuroscience↗

bioRxiv2025

Enhanced fluorescence lifetime imaging microscopy denoising via principal component analysis

Fluorescence Lifetime Imaging Microscopy (FLIM) quantifies the autofluorescence lifetime to measure cellular metabolism, therapeutic efficacy, and disease progression. These dynamic processes are intrinsically heterogeneous, increasing the complexity of the signal analysis. Often noise reduction strategies that combine thresholding and non-selective data smoothing filters are applied. These can result in error introduction and data loss. To mitigate these issues, we develop noise-corrected principal component analysis (NC-PCA). This approach isolates the signal of interest by selectively identifying and removing the noise. To validate NC-PCA, a secondary analysis of FLIM images of patient-derived colorectal cancer organoids exposed to a range of therapeutics was performed. First, we demonstrate that NC-PCA decreases the uncertainty up to 4-fold in comparison to conventional analysis with no data loss. Then, using a merged data set, we show that NC-PCA, unlike conventional methods, identifies multiple metabolic states. Thus, NC-PCA provides an enabling tool to advance FLIM analysis across fields.

bioengineering↗

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↗