A formal representation of the mutual information processing among the cognitive processes of the brain provides a real impression of the mechanisms of a Natural Intelligence (NI) system. The nature of information processing in the human brain is fuzzy. In this article, a new formal model, namely Cellular Fuzzy Networks (CFNs), is introduced to model the real characteristics of NI-Systems and especially the human mind. CFNs can effectively manipulate the interactions among natural concepts in an NI-system. The detailed definitions of CFNs and related theorems are provided. Then, CFNs are exploited to model a feasibility analysis of the human brain in the cognitive process of decision making. Finally, it is posited that CFNs have great potential to be applied in modeling the complex interrelationships in large-scale natural systems.