power of rhythmic activity
G.V. Portnova, G.A. Ivanitsky, E.V. Sharova, A.M. Ivanitsky
Electroencephalographic research attended by three groups of subjects: healthy adults, children and patients in a coma. The aim of the research was to find indicators of brain activity in patients and identification of predictors that can predict their future dynamics. It is suggested that, despite the absence of any behavioral activity, patients can be diagnosed with some brain activity, distinct from the brain activity of healthy adults. The level of preservation of cognitive function can be determined by measuring the response of the brain rhythms to emotionally significant stimuli. Such a response has prognostic value and can be used as effective rehabilitation procedure. Identification of brain activity is possible only upon presentation of relevant stimuli that are emotional, sensual and even vital component. In a pilot study subjects were presented with stimuli in the tactile and audio modalities, which have different significance for different test and cognitive complexity. As a tactile stimulation used pleasant stimuli (holding his arm with a soft brush), unpleasant (holding the arm prickly brush), as well as writing on the hand of different words. Auditory stimuli contained sounds, reflecting a certain physiological state (cough, vomiting), emotional state (laughing, crying), nature sounds (bird song, rain), human speech, household sounds (gnashing of forks on a plate), the incentives that cause orienting reaction, and neutral sounds. EEG was recorded using portable device "Entsefalan" with polygraph channels (POLY-4). Data analysis included search for significant differences in power of rhythmic activity for the different groups of stimuli compared to the background, changes in vegetative characteristics and the ERP. The differences in brain activity between different groups of subjects also were analyzed. It was found that patients in a coma reacted only to an emotionally significant stimulation. Decreasing of the emotional significance as well as an increasing of their cognitive complexity corresponds to a reduction reaction of patients. In addition, the change in the power of rhythmic brain activity in patients was closer to a change in rhythmic activity in children than adults.