M.V. Frolov, G.B. Milovanova, L.A. Potulova

A concept of functional states (FS) is suggested and the most important functions of a FS, reflective and regulatory, are determined. The reflective function postulates the dependence of the FS on a current need, external stimuli, and initial state. The regulatory function provides professional performance. The neurophysiological mechanism of the FS is presumably based on the interaction between the current motivational excitation and the afferent stream evoked by the external factor directed to the satisfaction of the current need. The systemic reaction of the body produced by this interaction serves the basis for the development of indices of the functional state. Regular changes in performance quality and reliability as well as errors of different modes were revealed during the recognition of noisy visual patterns. It was shown that the development of fatigue and increase in the negative emotional tension lead to the dominant reaction types. In fatigue, subjects tend to recognize signals as noise, whereas in the negative emotional state, noise tends to be defined as a signal. Emotional state of a high level eliminates initial (at the beginning of an experiment) differences between the stimulus-reaction-state curves. The values and phase shifts of the temporary recognition indices can be adequately assessed on the basis of the artifact-free records of super slow oscillations (the brain potentials and the heart rate), which characterize synchronization and desynchronization processes associated with the development of fatigue in the brain areas involved in the activity. In the latter case the super slow component appears also in the recognition parameters. Secretly recorded melodic speech parameters were shown to be efficient in quantitative estimation of the state of a female patient in the process of her depressive state treatment. Such kinds of tasks are especially important both for increasing reliability of operator-s performance and for the diagnostics and treatment of depressive diseases. On the other hand, in the extreme domain of the above mentioned functions, the emotional state of a subject becomes optimal (the reliability and quality of professional performance are maximal). Emotionally excited human operator keeps the vigilance at a rather high level for a rather long time, however, he/she begins to subjectively perceive objectively nonsignificant stimuli as significant ones