Acute DOI exposure drives cortical hyperexcitability and functional network remodeling.

Serotonergic psychoplastogens can produce durable cortical remodeling, but how a brief exposure to the 5-HT2A agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) reshapes population activity and functional connectivity remains unclear. We recorded primary rat cortical cultures on spatially defined microelectrode arrays before and after acute DOI exposure using a within-culture repeated-measures design, with a separate ketanserin + DOI arm to probe 5-HT2A receptor involvement. Network activity was summarized from spikes, bursts, and functional connectivity estimated with Pearson cross-correlation and the rate-corrected spike-time tiling coefficient. Following DOI exposure, mean firing rate increased across all six wells, burst timing accelerated, and functional-network metrics showed a convergent but sensitivity-limited shift toward shorter characteristic path length. Ketanserin + DOI exposure reduced population bursting and prolonged inter-burst intervals, while descriptive path-length shortening persisted. Path-length shortening persisted under the rate-corrected STTC estimator, suggesting that the connectivity shift was not simply a firing-rate artifact. These findings show that acute DOI exposure can move dissociated cortical cultures into a hyperexcitable population state with altered functional-network dynamics. Multiplexed cortical network recordings therefore provide a tractable bridge between molecular psychoplastogen biology and systems-level circuit outcomes relevant to durable therapeutic plasticity.