Rich dynamics and functional organization on topographically designed neuronal networksin vitro

Abstract

Neuronal cultures are a prominent experimental tool to understand complex functional organization in neuronal assemblies. However, neurons grown on flat surfaces exhibit a strongly coherent bursting behavior with limited functionality. To approach the functional richness of naturally formed neuronal circuits, here we studied neuronal networks grown on polydimethylsiloxane (PDMS) topographical patterns shaped as either parallel tracks or square valleys. We followed the evolution of spontaneous activity in these cultures along 20 days in vitro using fluorescence calcium imaging. The networks were characterized by rich spatiotemporal activity patterns that comprised from small regions of the culture to its whole extent. Effective connectivity analysis revealed the emergence of spatially compact functional modules that were associated to both the underpinned topographical features and predominant spatiotemporal activity fronts. Our results show the capacity of spatial constraints to mold activity and functional organization, bringing new opportunities to comprehend the structure-function relationship in living neuronal circuits.

Long-term calcium imaging reveals functional development in hiPSC-derived cultures comparable to human but not rat primary cultures

“…This strong synchronization, in turn, led to functional networks that were excessively integrated, a condition that is considered pathological when compared with healthy brain-like behavior ( Deco et al., 2015 ). A richer repertoire of activity and functionality in rat primary cultures could be favored by imprinting modular characteristics in the network, for instance through strong aggregation ( Teller et al., 2014 ; Okujeni and Egert, 2019 ; Tibau et al., 2020 ) or fine-tuned neuro-engineering ( Yamamoto et al., 2018 ; Montalà-Flaquer et al., 2022 ). By contrast, hiPSC-derived cultures exhibited a broad repertoire of activity patterns (functional segregation), and the synchronous-like behavior present at late stages did not dominate network dynamics.…”

“…Functional connectivity matrices were analyzed using the “Brain Connectivity Toolbox” ( Rubinov and Sporns, 2010 ) to quantify the topological organization of the studied cultures. Five main network properties were used and are described in detail in the supplemental information and in Ludl and Soriano (2020 ) and Montalà-Flaquer et al. (2022 ).…”