Neurons in the brain produce numerous patterns of spiking activity to represent information at every moment.These patterns are constrained not only by their pairwise correlations but also by interactions among groups of neurons larger than 2, known as higher-order interactions (HOIs).However, the primary characteristics of HOIs common to neural populations are unknown.Here we report that spontaneously active neurons in the CA3 area of cultured hippocampal slices become simultaneously silent more frequentlv than predicted by their individual activity rates and pairwise correlations.