Frequency-Dependent Synaptic Plasticity and Homeostatic Regulation under Rhythmic Modulation of In Vitro Hippocampal Networks

Synaptic plasticity is a fundamental mechanism underlying learning and memory, through which neuronal networks in the brain exhibit rhythmic activity at distinct frequencies (e.g., θ and γ oscillations) to enable efficient information processing and maintain network stability. However, the plasticity rules of in vitro neuronal networks under different stimulation frequencies, as well as their regulatory responses to rhythmic driving, remain insufficiently characterized. To investigate how in vitro neuronal networks achieve learning and memory processes, we cultured mice hippocampal networks on multielectrode arrays (MEAs) and conducted two related experiments. (1) Electrical stimulation patterns at distinct frequencies, combined with network connectivity analysis, demonstrated clear frequency-dependent plasticity, reflecting core properties of learning and memory. (2) Physiologically relevant rhythmic stimulation (θ: 7.8 Hz, γ: 40 Hz) with varying intensities was then applied. Although both rhythms induced distinct frequency-specific modulation, increasing stimulation intensity led to a pronounced suppression of frequency-dependent plasticity, revealing an intrinsic homeostatic regulatory mechanism. Together, out findings characterize frequency-dependent plasticity of in vitro hippocampal networks and uncover their adaptive homeostatic regulation under rhythmic modulation. These results advance our understanding of learning and memory mechanisms and provide a foundation for leveraging in vitro neural systems to perform complex learning and memory tasks.