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Jafarian, M.

Publications and source records attributed to Jafarian, M..

2 recordsLinked to original sources

Data-driven oscillatory network modeling with condition-dependent coupling laws: Identifying directed neural interactions in working memory attention dynamics

Learning new information in the presence of distracters and changing conditions requires the ability to adapt. In the brain, this adaptive capability has been linked to dynamic interactions between attention and working memory, which enable the selective filtering of irrelevant input while preserving behaviorally relevant information. Specific neural oscillations have been implicated in this process. Here, we introduce a phenomenological data-driven framework for oscillatory network modeling that learns condition-dependent coupling laws directly from neural recordings and enables inference of condition-dependent directed pathways. We apply our approach to magnetoen-cephalography (MEG) data collected while participants performed a working-memory task with and without distracters. Recall dynamics in the non-distracter condition are first modeled using a linear oscillatory network in which each region of interest is represented by two alpha-band harmonic oscillators. We use universal differential equations (UDE), an extension of neural differential equations, to capture distracter-induced changes in coupling laws. Symbolic regression is then used to interpret the modifications identified by UDE as nonlinear functions, and an additional method is proposed to identify the directed pathway from the newly emerging nonlinear terms in the dynamics of brain regions of interest. Despite inter-subject variability, working memory recall data from all four participants examined under distraction showed the emergence of a pathway from the dorsolateral prefrontal cortex (dlPFC) to the primary visual cortex (V1). This finding is consistent with the established role of the dlPFC in cognitive control and suggests that distracter processing recruits a directed interaction from prefrontal to visual regions. More broadly, our results illustrate that combining linear models whose parameters are learned from the data with universal differential equations augmented by interpretability methods enables the identification of condition-dependent coupling laws, their representation as interpretable mathematical functions, and the discovery of candidate directed pathways underlying adaptive changes in oscillatory networks without requiring strong prior assumptions about the underlying mechanisms.

neuroscience↗

Associative emotional memory encoding: Insights from network stability analysis of an fMRI-driven bilinear dynamics

The interplay between emotion and memory is a central topic in cognitive neuroscience, with open questions about the underlying neuronal mechanisms. This article studies dynamic interactions among the hippocampus, amygdala, and orbitofrontal cortex during an fMRI associative memory encoding task. Participants were clustered into three condition groups: Neutral-Neutral, Neutral-Emotional, or Emotional-Emotional, and viewed image pairs associated with their assigned condition. Using the dynamic causal modeling framework, we explore several dynamic models and show that a stochastic bilinear state-space model best describes the neuronal dynamics in all conditions. Furthermore, we use graph and control theory techniques to both validate and analyze the model. In particular, we analyze the network dynamics of each condition using tools from graph theory and stability theory and discuss the differences in the strength and direction of connectivity as well as the stability of each of these networks. We confirm the prior finding that memory is enhanced in emotional conditions, in particular in the Neutral-Emotional condition. In our work, this enhanced memory is associated with increased hippocampus-amygdala coupling and overall network connectivity. In addition, we show that in the Emotional-Emotional condition, the coupling of the hippocampus and amygdala, as well as the whole network connectivity increases when the first images valence is substantially less negative rated than the second image. This pattern mirrors the Neutral-Emotional condition, where the first image is neutral compared with the second one. Moreover, our model-based analyses suggest that the amygdala predominantly influences the other two regions in the Neutral-Emotional condition, whereas the OFC plays a dominant role in the other two conditions. Combined data-driven modeling, stability analyses, and graph-theory tools led to new insights and enhanced the mechanistic understanding of cortical dynamics of emotional associative memory. We discuss these insights, utilize these analytical tools to generalize our findings to some unmeasured conditions, and highlight the potential of these techniques to inform the design of future regulatory mechanisms.

neuroscience↗