Changes in EEG and Reaction Times during the Treatment of Apathetic Depression

The aim of the present work was to identify neurophysiological correlates of the dynamics of the functional state of the brain in patients aged 20–51 years with apathetic depression during treatment. The spectral parameters of baseline electroencephalograms (EEG) and the latent periods of simple sensorimotor reactions and two-choice selection reactions to auditory stimuli were studied. At the stage of marked improvements in clinical status, patients showed a complex rearrangement of the temporospatial structure of the EEG, including EEG signs of increased inhibitory processes (in the form of increases in the spectral power of slow-wave delta, theta1, and theta2 activity), mainly in the frontal, central, and temporal zones of the right hemisphere, EEG signs of decreased activation of the temporal areas (in the form of a reduction in the spectral power of beta activity, especially in the right hemisphere), and EEG signs of increased activation of the anterior areas of the cortex of the left hemisphere of the brain by excitatory brainstem reticular structures (in the form of increases in the spectral power of beta activity in the left frontal and central zones). There were also decreases in the mean latent periods of a simple sensorimotor reaction and a twochoice selection reaction. These data are consistent with contemporary concepts of the predominant role of the right hemisphere in regulating negative emotions and the pathogenesis of depression.