Abstract: Inconsistent data on local activity and distant interactions of individual elements in brain systems is still an unsolved problem in studying systemic activity of the human brain. A phenomenon of hidden nodes has recently been discovered in the field; i.e., several brain structures can be involved in their function exclusively via changes in distant functional connections, but without a detectable change in energy consumption. A study of hidden nodes was continued using the fMRI data obtained in conditions of image identification and categorization. A means to localize the hidden nodes was proposed, and methods of the graph theory were used to verify the critical role of hidden nodes in systemic activity of the brain. It was found additionally that different types of hidden nodes may exist to perform different functions in the configuration of brain systemic activity.