P112 Dopamine effects on firing patterns of in vitro hippocampal neurons
Huu Hoang*1, Aurelio Cortese2
1Neural Information Analysis Laboratories, ATR Institute International, Kyoto, Japan 2Computational Neuroscience Laboratories, ATR Institute International, Kyoto, Japan
*Email: hoang@atr.jp
Introduction:Dopamine plays a pivotal role in shaping hippocampal neural activity, yet its impact on network dynamics is not fully understood. We explored this by recording rat embryonic hippocampal neurons in vitro, using electrophysiological techniques, pharmacological manipulations, and spike train analysis. Our findings reveal that dopamine reduces network synchrony, broadening the range of burst dynamics—an effect absent with dopamine antagonists. This study deepens our insight into how dopamine signaling shapes functional hippocampal networks.
Methods:We cultured eight rat embryonic hippocampus samples and used MaxOne microelectrode arrays to record spiking activity from hundreds of electrodes. Baseline spikes were captured without dopamine, then dopamine was added gradually, and spikes were recorded. We assessed synchrony strength via spike coherence in 1 msec bins and examined dopamine’s effect on spike dynamics. Spike bursts (typically in 200-300 ms) were detected, and their similarity index was measured. Using affinity propagation on the similarity index, we identified repeating burst motifs, revealing insights into burst dynamics. We used linear mixed-effect models to statistically evaluate the influence of dopamine on the metrics of interest.
Results:Our study revealed that dopamine lowers synchrony strength, enhances network modularity, and restricts connectivity within modules, while broadening burst pattern variety. At higher dopamine concentrations (300-1000 μM), burst frequency rose, yet burst similarity dropped, with repeating motifs surging 40-50% above baseline. The reduction in synchrony caused by dopamine directly lessened burst pattern similarity, shown by a robust positive correlation between synchrony and similarity changes in eight samples. This relationship disappeared in samples treated with dopamine antagonists, underscoring dopamine’s critical influence on reorganizing network dynamics and its possible role in cognitive processes.
Discussion:We investigated dopamine’s impact on cultured hippocampal neurons using high-density electrode arrays, observing a rise in burst events with pronounced synchrony across hundreds of electrodes after incrementally adding dopamine, consistent with previous studies. This setup provided detailed network-level insights with cellular and millisecond precision, showing dopamine reduced spike synchrony while increasing the number of network modules with more restricted connectivity. Such reorganization may optimize information flow for cognitive functions like memory and decision-making. Dopamine also diversified burst patterns, boosting repeating motifs and lowering burst similarity—an effect blocked by antagonists. These findings suggest dopamine enhances distinct encoding in hippocampal circuits, offering potential implications for understanding cognition and schizophrenia therapies.
Acknowledgements This study was supported by JST ERATO (JPMJER1801, "Brain-AI hybrid").
References Hoang H, Matsumoto N, Miyano M, Ikegaya Y, Cortese A. (2025). Dopamine-induced relaxation of spike synchrony diversifies burst patterns in cultured hippocampal networks.Neural Networks; 181:106888. doi: 10.1016/j.neunet.2024.106888.
