ABSTRACT
Objective To investigate the characteristics of spontaneous discharges of hippocampal pyramidal cells (PC) in rats in age and memory groups with the help of nonlinear theory. Methods Rats were randomly divided into age group and memory group. Age group included aged group (16-19 months) and young group (3-4 months) whereas memory group included good memory and poor memory groups in adult. Extracellular single cell recording was performed in vivo . Results No characteristics of the rhythm of spontaneous discharges of hippocampal pyramidal cells in distribution figure of interspike interval(ISI) were found, but the loss of complexity(C) and low percentage of favored patterns(PF) were found in age and poor memory groups. Conclusion The ISI complexity and the PF of the hippocampal pyramidal cells are correlated to age and memory, suggesting that the analysis of the complexity and favored patterns may be helpful for the discovery of the characteristics of the information coding in spontaneous discharges of hippocampal pyramidal cells.