Tentacle Microelectrode Arrays Uncover Soft Boundary Neurons in Hippocampal CA1

Abstract Hippocampal CA1 neurons show intense firing at specific spatial locations, modulated by isolated landmarks. However, the impact of real‐world scene transitions on neuronal activity remains unclear. Moreover, long‐term neural recording during movement challenges device stability. Conventional rigid‐based electrodes cause inflammatory responses, restricting recording durations. Inspired by the jellyfish tentacles, the multi‐conductive layer ultra‐flexible microelectrode arrays (MEAs) are developed. The tentacle MEAs ensure stable recordings during movement, thereby enabling the discovery of soft boundary neurons. The soft boundary neurons demonstrate high‐frequency firing that aligns with the boundaries of scene transitions. Furthermore, the localization ability of soft boundary neurons improves with more scene transition boundaries, and their activity decreases when these boundaries are removed. The innovation of ultra‐flexible, high‐biocompatible tentacle MEAs improves the understanding of neural encoding in spatial cognition. They offer the potential for long‐term in vivo recording of neural information, facilitating breakthroughs in the understanding and application of brain spatial navigation mehanisms.