Individual stable patterns of human brain rhythms as a reflection of mental processes

Abstract

Here, we attempt to summarize our research conducted for more than twenty years. Back in 1997, we were the first to publish the data indicating that the type of cognitive task (spatial or arithmetic) performed by a subject can be identified with a reliability of 70 to 98% (dependent on a subject) by analyzing the EEG spectra and using an artificial neural network. Further research led us to the understanding that any sustainable mental activity was accompanied by characteristic rhythmic EEG patterns. Individual EEG rhythms (that in totality form a pattern) differ in their frequency and topography. Cognitive patterns of EEG rhythms have a number of fundamental characteristics. They are highly specific and stable in each individual and persist for years (slowly changing); they are also highly specific for each type of cognitive activity. Later it was found that the arising patterns of brain rhythms were not only different for different types of cognitive tasks but also interrelated with each other in the way similar to the inter-relations of psychological characteristics of the tasks. Based on this finding, we have developed a method for creating a map of a person’s cognitive space. It turned out that, by using this method, one can draw maps of a human sensory-emotional space. In experiments with the presentation of equivalent audial and visual tasks, we found that the EEG rhythm patterns reflected the very nature of mental acts, and not processes of sensory perception. The developed methods for distinguishing between different mental states and for creating mental space maps have found their practical use including that in medicine. In mental illnesses, the thinking ability is impaired, which is manifested in changes in the cognitive rhythmic patterns of the EEG. When consciousness is depressed, the emotional-sensory spaces reflect rather the physical properties (and not the emotional content) of the stimuli presented to patients. The accumulated knowledge made it possible to develop a device prototype (called “cognovisor”), which allows for real-time tracking of one’s thinking process and displaying it on a map of the individual cognitive space.