Detection of Neuronal Defensive Discharges Information Transmission and Characteristics in the Periaqueductal Gray Double-Subregions Using PtNPs/PEDOT:PSS-modified Microelectrode Arrays

Abstract Appropriate defensive behaviors were selected and rapidly executed to survive in threatened animals. It was accepted the midbrain periaqueductal grey (PAG) presents an essential part of the circuitry that organize defensive behavioral responses. However, the role and correlation of different PAG subregions in the expression of different defensive behaviors remained largely unexplored. Here, we designed and manufactured a microelectrode array (MEA) to simultaneously detect the activities of dPAG and vPAG neurons in freely-behaving rats. The PtNPs/PEDOT:PSS nanocomposites were modified onto the MEAs to improve the detection performances of the MEAs. Subsequently, the predator odor was used to induce the rat's innate fear, and the changes and information transmission in neuronal activities were detected in dPAG and vPAG. Our results showed that dPAG and vPAG both participated in the innate fear, but the activation degree was distinct in different defense behavior. During the flight, neuronal responses were stronger and earlier in the dPAG compared with the vPAG, while vPAG neurons responded greater during freezing. The application of high-performance MEA detected that neural information spread from activated dPAG to weakly activated vPAG. Our research also revealed that dPAG and vPAG neurons had different defensive discharges characteristics, and dPAG neurons participated in the regulation of defense response with burst-firing patterns. The slow activation and continuous-firing of vPAG neurons were matched with the regulation of long-term freezing response. The results demonstrated the important role of PAG neuronal activities in the control of different aspects of defensive behaviors and provided novel insights for investigating defense from the electrophysiological perspective.