Long‐Term Tracking and Dynamically Quantifying of Reversible Changes of Extracellular Ca 2+ in Multiple Brain Regions of Freely Moving Animals

Understanding physiological and pathological processes in the brain requires tracking the reversible changes in chemical signals with long‐term stability. We developed a new anti‐biofouling microfiber array to real‐time quantify extracellular Ca 2+ concentrations together with neuron activity across many regions in the mammalian brain for 60 days, in which the signal degradation was < ca. 8 %. The microarray with high tempo‐spatial resolution (ca. 10 μm, ca. 1.3 s) was implanted into 7 brain regions of free‐moving mice to monitor reversible changes of extracellular Ca 2+ upon ischemia‐reperfusion processes. The changing sequence and rate of Ca 2+ in 7 brain regions were different during the stroke. ROS scavenger could protect Ca 2+ influx and neuronal activity after stroke, suggesting the significant influence of ROS on Ca 2+ overload and neuron death. We demonstrated this microarray is a versatile tool for investigating brain dynamic during pathological processes and drug treatment.