Makdah, G. | Search bioRxiv

bioRxiv2024

Detection of cell assemblies in high-density extracellular electrophysiological recordings

Cell assemblies, i.e., concurrently active groups of neurons, likely underlie neural processing for higher brain functions. Recent technological progress has enabled large-scale recording of neuronal activity, permitting the exploration and analysis of cell assembly dynamics. This review aims to provide both conceptual insights and practical knowledge pertaining to principal methodologies used for detecting cell assemblies in the last fifteen years. The goal is to assist readers in selecting and comparing various protocols to optimize their data processing and analysis pipeline. Each algorithm is explained with its fundamental principles, their application in neuroscience for cell assembly detection, and illustrated with published studies. Recognizing the similarities, advantages, and drawbacks of diverse methodologies may pave the way for developing new procedures for cell assembly identification to facilitate future endeavors in the understanding of brain activity.

neuroscience↗

bioRxiv2021

Post-trauma behavioral phenotype predicts vulnerability to fear relapse after extinction

Current treatments for trauma-related disorders remain ineffective for many patients. Here, we modeled interindividual differences in post-therapy fear relapse with a novel ethologically relevant trauma recovery paradigm. After traumatic fear conditioning, male rats underwent fear extinction while foraging in a large enriched arena, permitting the expression of a wide spectrum of behaviors, assessed by an automated pipeline. This multidimensional behavioral assessment revealed that post-conditioning fear response profiles clustered into two groups, respectively characterized by active vs. passive fear responses. After trauma, some animals expressed fear by freezing, while others darted, as if fleeing from danger. Remarkably, belonging to the darters or freezers group predicted differential levels of vulnerability to fear relapse after extinction. Moreover, genome-wide transcriptional profiling revealed that these groups differentially regulated specific sets of genes, some of which have previously been implicated in anxiety and trauma-related disorders. Our results suggest that post-trauma behavioral phenotypes and the associated epigenetic landscapes can serve as markers of fear relapse susceptibility, and thus may be instrumental for future development of more effective treatments for psychiatric patients.

neuroscience↗