This chapter presents the results of two pilot studies, both of which demonstrate a significant change of the brain’s functional state after 20 sessions of ILF NF. The first study includes eight healthy subjects with no history of neurological or psychiatric disorders. After completion of 20 ILF Neurofeedback sessions, most participants indicated a decrease of inner tension and reactivity to stressful factors and an improvement of body and space awareness, cognitive performance, and mood stability. The data obtained show that the spectral power of slow EEG oscillations in 0.01–0.5 Hz frequency band significantly increase in the post-training recording as compared with the pre-training baseline. The second study describes changes of symptoms and EEG parameters in three unmedicated depressed individuals after 20 sessions of ILF NF training. The clinical symptoms in each subject are given along with the pre- and post-treatment Depression Rating Scales (MARDS, HAMD, and BDI) assessment.

After finishing the training course, all three participants reported remarkable improvement of mood and emotional stability, decrease of anxiety level and reactivity to stressful situations, and an increase in concentration and mental performance. The post-treatment Depression Rating Scales, as compared to pre-treatment ones, revealed dramatic decrease of the depression scores up to the norm. The Quantitative EEG parameters in Eyes open and Eyes closed resting states, and during the visual GO/NOGO task, show significant decrease of theta power over frontal and central areas in all three patients in post-treatment EEG recordings, as compared to pre-treatment EEGs. Correlation of remission of the clinical symptoms of depression and positive changes in brain wave activity with improvement of cortical functional activity in frontal area after an ILF NF course are discussed.