Biology subjects

Hadaeghi, F.

Publications and source records attributed to Hadaeghi, F..

4 recordsLinked to original sources

bioRxiv2024

Controlling Reciprocity in Binary and Weighted Networks: A Novel Density-Conserving Approach

We introduce efficient Network Reciprocity Control (NRC) algorithms for steering the degree of asymmetry and reciprocity in binary and weighted networks while preserving fundamental network properties. Our methods maintain edge density in binary networks and cumulative edge weight in weighted graphs. We test these algorithms on synthetic benchmark networks, including random, small-world, and modular structures, as well as brain connectivity maps (connectomes) from various species. We demonstrate how adjusting the asymmetry-reciprocity balance under edge density and total weight constraints influences key network features, including spectral properties, degree distributions, community structure, clustering, and path lengths. Additionally, we present a case study on the computational implications of graded reciprocity by solving a memory task within the reservoir computing framework. Furthermore, we establish the scalability of the NRC algorithms by applying them to networks of increasing size. These approaches enable systematic investigation of the relationship between directional asymmetry and network topology, with potential applications in computational and network sciences, social network analysis, and other fields studying complex network systems where the directionality of connections is essential.

neuroscience↗

bioRxiv2024

A General Framework for Characterizing Optimal Communication in Brain Networks

Communication in brain networks is the foundation of cognitive function and behavior. A multitude of evolutionary pressures, including the minimization of metabolic costs while maximizing communication efficiency, contribute to shaping the structure and dynamics of these networks. However, how communication efficiency is characterized depends on the assumed model of communication dynamics. Traditional models include shortest path signaling, random walker navigation, broadcasting, and diffusive processes. Yet, a general and model-agnostic framework for characterizing optimal neural communication remains to be established. Our study addresses this challenge by assigning communication efficiency through game theory, based on a combination of structural data from human cortical networks with computational models of brain dynamics. We quantified the exact influence exerted by each brain node over every other node using an exhaustive multi-site virtual lesioning scheme, creating optimal influence maps for various models of brain dynamics. These descriptions show how communication patterns unfold in the given brain network if regions maximize their influence over one another. By comparing these influence maps with a large variety of brain communication models, we found that optimal communication most closely resembles a broadcasting model in which regions leverage multiple parallel channels for information dissemination. Moreover, we show that the most influential regions within the cortex are formed by its rich-club. These regions exploit their topological vantage point by broadcasting across numerous pathways, thereby significantly enhancing their effective reach even when the anatomical connections are weak. Our work provides a rigorous and versatile framework for characterizing optimal communication across brain networks and reveals the most influential brain regions and the topological features underlying their optimal communication.

neuroscience↗

bioRxiv2023

Differential Patterns of Associations within Audiovisual Integration Networks in Children with ADHD

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition characterized by symptoms of inattention and impulsivity and has been linked to disruptions in functional brain connectivity and structural alterations in large-scale brain networks. While anomalies in sensory pathways have also been implicated in the pathogenesis of ADHD, exploration of sensory integration regions remains limited. In this study, we adopted an exploratory approach to investigate the connectivity profile of auditory-visual integration networks (AVIN) in children with ADHD and neurotypical controls, utilizing the ADHD-200 rs-fMRI dataset. In addition to network-based statistics (NBS) analysis, we expanded our exploration by extracting a diverse range of graph theoretical features. These features served as the foundation for our application of machine learning (ML) techniques, aiming to discern distinguishing patterns between the control group and children with ADHD. Given the significant class imbalance in the dataset, ensemble learning models like balanced random forest (BRF), XGBoost, and EasyEnsemble classifier (EEC) were employed, designed to cope with unbalanced class observations. Our findings revealed significant AVIN differences between ADHD individuals and neurotypical controls, enabling automated diagnosis with moderate accuracy. Notably, the XGBoost model demonstrated balanced sensitivity and specificity metrics, critical for diagnostic applications, providing valuable insights for potential clinical use. These findings offer further insights into ADHDs neural underpinnings and high-light the potential diagnostic utility of AVIN measures, but the exploratory nature of the study underscores the need for future research to confirm and refine these findings with specific hypotheses and rigorous statistical controls.

neuroscience↗

bioRxiv2023

When Neural Activity Fails to Reveal Causal Contributions

Neuroscientists rely on distributed spatio-temporal patterns of neural activity to understand how neural units contribute to cognitive functions and behavior. However, the extent to which neural activity reliably indicates a units causal contribution to the behavior is not well understood. To address this issue, we provide a systematic multi-site perturbation framework that captures time-varying causal contributions of elements to a collectively produced outcome. Applying our framework to intuitive toy examples and artificial neuronal networks revealed that recorded activity patterns of neural elements may not be generally informative of their causal contribution due to activity transformations within a network. Overall, our findings emphasize the limitations of inferring causal mechanisms from neural activities and offer a rigorous lesioning framework for elucidating causal neural contributions.

neuroscience↗