Biology subjects

Dhamala, M.

Publications and source records attributed to Dhamala, M..

7 recordsLinked to original sources

bioRxiv2026

On Complexity in Resource Constrained Neuronal Systems: Dynamic Resource Theory

Understanding how complex systems self-organize, exhibit emergent properties beyond their constituent elements remains a challenge across physics, biology, and cognitive science. In resource-constrained neuronal systems, existing theoretical approaches, including gauge theoretic formulations, statistical physics-inspired methods, dynamical population models, and variational principles such as the Free Energy Principle, address important aspects of this problem but do not fully specify the physical conditions and thermodynamic costs under which self-organizing behavior occurs. Here, we introduce Dynamic Resource Theory (DRT) as a general physical framework for describing self-organization under constrained resource availability. DRT formalizes complexity as a physical property of self-organizing systems arising from coupled mechanisms of resource allocation and dynamic reallocation of internal resources. This framework provides a thermodynamic and variational account of how stability is preserved while adaptive reconfiguration remains possible, consistent with stationary action and thermodynamic constraints. DRT is formulated within a gauge theoretic setting and directly incorporates the energetic costs associated with maintaining structure and enabling system-level reconfiguration. Within DRT, baseline resource allocation preserves system stability, while internal and external demands perturb the system, driving self-organization through dynamic resource reallocation across a coupled free energy landscape without assuming subsystem separability. We then develop Neural Resource Theory (NRT) and Cognitive Resource Theory (CRT) as principled specializations of DRT, illustrating how this structure is instantiated in resource constrained neuronal and cognitive systems. We conclude by discussing the broader implications of DRT for understanding how complexity, emergence, and adaptive capacity arise over time through thermodynamically permissible reallocation processes across scales.

neuroscience↗

bioRxiv2025

Level Up the Brain! Novel PCA Method Reveals Key Neuroplastic Refinements in Action Video Gamers

Action video games (AVGs) offer an ecologically rich experimental paradigm for studying how sustained cognitive demands drive behaviorally induced neuroplastic changes in the brain. We demonstrate that the neuroplastic refinements observed in long-term AVG players, referred to in this study as gamers, reflect more efficient neural mechanisms for reducing visuomotor information surprise during visuomotor decision-making by more effectively resolving internal conflict in competing motor plans, thus reducing uncertainty. To explain how such adaptations unfold over time, we utilized the Cognitive Resource Reallocation (CRR) framework, defined as the dynamic redistribution of metabolic and functional resources to support behaviorally relevant neuroplastic adaptation under repeated, demanding task conditions. Using a novel region-cumulative principal component analysis (rcPCA) approach, we identified key brain regions that explain inter-subject variability, improving statistical power by isolating the most informative regions and reducing the burden of multiple comparisons. Our findings suggest that prolonged AVG experience fosters more efficient visuomotor decision-making through top-down cognitive clarity, as reflected in the unobstructed transformation of learned value into goal-directed action, and bottom-up motor readiness, enabling improved visuomotor performance in gamers. These converging adaptations reduce internal conflict, mitigate uncertainty, and enable rapid yet skillful action selection. In sum, the brains of long-term gamers exhibit neuroplastic refinements consistent with CRR, marked by more effective transformation of sensory input into coherent motor output--an advantage especially critical in high-pressure environments. More broadly, these results illustrate how repeated cognitive challenge can perturb neurodynamic equilibria in ways that promote adaptive functional reorganization and enhanced cognitive ability.

neuroscience↗

bioRxiv2025

Structurally Constrained Functional Connectivity Reveals Efficient Visuomotor Decision-Making Mechanisms in Action Video Gamers

Long-term action video game (AVG) playing has been linked to improved response times ([~]190 ms) without accuracy tradeoffs in time-sensitive visuomotor decisions, but how it reshapes neural circuits that enable this behavioral advantage is unclear. In this study, Cognitive Resource Reallocation (CRR) is introduced as a candidate mechanism for how sustained engagement with AVGs drives behaviorally relevant neuroplasticity through neuroplastic refinement. Using the AAL3 structural connectivity atlas, we apply structural constraints to functional connectivity (SC-FC) and directed functional connectivity (SC-dFC) in gamers and non-gamers. Our results provide strong support for the CRR hypothesis and demonstrate that the brain plausibly reallocates cognitive resources over time to optimize task-relevant networks in high-demand environments such as AVGs, enhancing the integration of contextual information and refining motion processing, which may be a key mechanism in explaining more efficient visuomotor decision-making. These findings position action video games as powerful tools for studying experience-driven neuroplasticity, with implications for cognitive training, rehabilitation, and optimizing real-world visuomotor decisions.

neuroscience↗

bioRxiv2024

Connectivity in the Dorsal Visual Stream is Enhanced in Action Video Game Players

Action video games foster competitive environments that demand rapid spatial navigation and decision-making. Action video gamers often exhibit faster response times and slightly improved accuracy in vision-based sensorimotor tasks. However, the underlying functional and structural changes in the two visual streams of the brain that may be contributing to these cognitive improvements have been unclear. Using functional and diffusion MRI data, this study investigated the differences in connectivity between gamers who play action video games and nongamers in the dorsal and ventral visual streams. We found that action video gamers have enhanced functional and structural connectivity, especially in the dorsal visual stream. Specifically, there is heightened functional connectivity--both undirected and directed--between the left Superior Occipital Gyrus and the left Superior Parietal Lobule during a moving-dots discrimination decision-making task. This increased connectivity correlates with response time in gamers. The structural connectivity, as quantified by diffusion fractional anisotropy and quantitative anisotropy measures of the axonal fiber pathways between the same regions was also enhanced for gamers compared to nongamers. These findings provide valuable insights into how action video gaming can induce targeted neuroplastic changes, enhancing structural and functional connectivity between specific brain regions in the visual processing pathways. These connectivity changes in the dorsal visual stream underpin the superior performance of action video gamers compared to non-gamers in tasks requiring rapid and accurate vision-based decision-making. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=169 SRC="FIGDIR/small/615213v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1ebf169org.highwire.dtl.DTLVardef@1363d13org.highwire.dtl.DTLVardef@1e3c08eorg.highwire.dtl.DTLVardef@176e719_HPS_FORMAT_FIGEXP M_FIG C_FIG Impact StatementUnderstanding the neural mechanisms underlying how observed cognitive alterations due to video game playing are achieved has potential implications for future cognitive training, rehabilitation, and education. The structural and functional MRI analysis in this study provides a quantitative basis by which the underlying neural connectivity changes due to video game playing in the visual streams may be assessed and linked to observed behavioral differences. These methods are extendible and provide insight into underlying neural network enhancements associated with improved cognitive performance due to video game playing. The findings of this study support enhanced functional and structural connectivity in the dorsal visual stream among gamers due to video game playing in the behavioral paradigm of vision-based sensorimotor decision-making. Functional connectivity measures that were considered were significantly correlated with the participants response times.

neuroscience↗

bioRxiv2023

Networks extracted from nonlinear fMRI connectivity exhibit unique spatial variation and enhanced sensitivity to differences between individuals with schizophrenia and controls

Functional magnetic resonance imaging (fMRI) studies often estimate brain intrinsic connectivity networks (ICNs) from temporal relationships between hemodynamic signals using approaches such as independent component analysis (ICA). While ICNs are thought to represent functional sources that play important roles in various psychological phenomena, current approaches have been tailored to identify ICNs that mainly reflect linear statistical relationships. However, the elements comprising neural systems often exhibit remarkably complex nonlinear interactions that may be involved in cognitive operations and altered in psychiatric conditions such as schizophrenia. Consequently, there is a need to develop methods capable of effectively capturing ICNs from measures that are sensitive to nonlinear relationships. Here, we advance a novel approach to estimate ICNs from explicitly nonlinear whole-brain functional connectivity (ENL-wFC) by transforming resting-state fMRI (rsfMRI) data into the connectivity domain, allowing us to capture unique information from distance correlation patterns that would be missed by linear whole-brain functional connectivity (LIN-wFC) analysis. Our findings provide evidence that ICNs commonly extracted from linear (LIN) relationships are also reflected in explicitly nonlinear (ENL) connectivity patterns. ENL ICN estimates exhibit higher reliability and stability, highlighting our approachs ability to effectively quantify ICNs from rsfMRI data. Additionally, we observed a consistent spatial gradient pattern between LIN and ENL ICNs with higher ENL weight in core ICN regions, suggesting that ICN function may be subserved by nonlinear processes concentrated within network centers. We also found that a uniquely identified ENL ICN distinguished individuals with schizophrenia from healthy controls while a uniquely identified LIN ICN did not, emphasizing the valuable complementary information that can be gained by incorporating measures that are sensitive to nonlinearity in future analyses. Moreover, the ENL estimates of ICNs associated with auditory, linguistic, sensorimotor, and self-referential processes exhibit heightened sensitivity towards differentiating between individuals with schizophrenia and controls compared to LIN counterparts, demonstrating the translational value of our approach and of the ENL estimates of ICNs that are frequently reported as disrupted in schizophrenia. In summary, our findings underscore the tremendous potential of connectivity domain ICA and nonlinear information in resolving complex brain phenomena and revolutionizing the landscape of clinical FC analysis.

neuroscience↗

bioRxiv2023

Spatial Dynamic Subspaces Encode Sex-Specific Schizophrenia Disruptions in Transient Network Overlap and its Links to Genetic Risk

BackgroundRecent advances in resting-state fMRI allow us to study spatial dynamics, the phenomenon of brain networks spatially evolving over time. However, most dynamic studies still use subject-specific, spatially-static nodes. As recent studies have demonstrated, incorporating time-resolved spatial properties is crucial for precise functional connectivity estimation and gaining unique insights into brain function. Nevertheless, estimating time-resolved networks poses challenges due to the low signal-to-noise ratio, limited information in short time segments, and uncertain identification of corresponding networks within and between subjects. MethodsWe adapt a reference-informed network estimation technique to capture time-resolved spatial networks and their dynamic spatial integration and segregation. We focus on time-resolved spatial functional network connectivity (spFNC), an estimate of network spatial coupling, to study sex-specific alterations in schizophrenia and their links to multi-factorial genomic data. ResultsOur findings are consistent with the dysconnectivity and neurodevelopment hypotheses and align with the cerebello-thalamo-cortical, triple-network, and frontoparietal dysconnectivity models, helping to unify them. The potential unification offers a new understanding of the underlying mechanisms. Notably, the posterior default mode/salience spFNC exhibits sex-specific schizophrenia alteration during the state with the highest global network integration and correlates with genetic risk for schizophrenia. This dysfunction is also reflected in high-dimensional (voxel-level) space in regions with weak functional connectivity to corresponding networks. ConclusionsOur method can effectively capture spatially dynamic networks, detect nuanced SZ effects, and reveal the intricate relationship of dynamic information to genomic data. The results also underscore the potential of dynamic spatial dependence and weak connectivity in the clinical landscape.

neuroscience↗

bioRxiv2017

Thalamocortical transmission of visual information in awake mice involves phase synchronization and spike synchrony at high gamma frequencies

AbstractSynchronization of neuronal spike activity is thought to play a key role in the transmission of information for sensory processing in the brain, and this synchronization is influenced by oscillatory population activity occurring in multiple frequency ranges at multiple stages of sensory pathways. In the neocortex, gamma frequency oscillations appear to play an important role in synchronizing neuronal ensembles and allowing for selective communication between regions, yet relatively little is known about whether gamma oscillations facilitate transmission of sensory information from thalamus to cortex. Here, we investigate the role of gamma oscillations in promoting synchronous spike activity between the visual thalamus (dLGN) and primary visual cortex (V1) in awake mice, a model sensory system with prominent gamma oscillations that are modulated by visual input. We demonstrate that transmission of visual information to cortex involves phase-synchronized oscillations in the high gamma range (50-90Hz), with concomitant millisecond-scale synchronization of thalamic and cortical spike activity. Transition from a full-field gray image to a high-contrast checkerboard image caused gamma activity to rapidly increase in amplitude, frequency, and bandwidth, yet the gamma oscillations in dLGN and V1 maintained a consistent phase relationship. High contrast stimulation also caused an increase in amplitude of oscillations in the beta and low gamma range, but those were not associated with synchronous thalamic activity. These results indicate a role for high gamma oscillations in mediating the functional connectivity between thalamic and cortical neurons in the visual pathway, a similar role to beta oscillations in primates.\n\nSignificance statementThe mechanisms by which neurons selectively communicate are essential to our understanding of how the brain processes information. Abundant evidence suggests that cortical sensory processing involves the synchronization of high frequency electric field oscillations known as gamma oscillations, which allow groups of neurons to synchronize their spike activity in order to collaboratively process sensory input. Here, we show that oscillations and spikes in the visual thalamocortical pathway of the mouse exhibit synchrony across a broad high gamma frequency range (50-90Hz), suggesting these oscillations play an important role in the relay of visual information to the cortex. This is substantially different from oscillations observed in monkeys, in which gamma is absent in thalamus and beta oscillations support thalamocortical relay.

neuroscience↗