DYNAMICS OF EEG COHERENCE CHARACTERISTICS IN TRANSCRANIAL MAGNETIC STIMULATION OF PATIENTS WITH THERAPY RESISTANT DEPRESSION
The aim of this investigation is to explore the dynamics of EEG coherence characteristics in transcranial magnetic stimulation (TMS) of patients with therapy resistant depression. Material: 32 patients diagnosed as having recurrent depressive disorder and bipolar affective disorder. The TMS as well as EEG-recordings were performed in the situation of unsuccessful thymo-analeptic medication and decreasing dose of this medication. The TMS was applied to the left prefrontal cortex area. The course of treatment consisted of 15 sessions with 100% intensity. During one session, the patient received 20 series of stimuli, with frequency 15 Hz and duration 6 sec., and intervals 60 seconds between the series. The EEG was registered by means of a Russian device НЕЙРО-КМ, with bandwidth 0,5 to 45 Hz and the time constant 0,3 before and after the course of TMS treatment. The authors determined the coherence and average coherence values for every area in relation to all other cortical areas. The investigation shows that TMS affects the synchronic generation of potentials in all cortical areas. According to average coherence values, significantly increased functional activity is found in left temporal cortex, as well as in parietal-central and frontal areas of both hemispheres. TMS significantly enhances functional hemispheric interaction between symmetrical frontal, central, fronto- and middle-temporal areas. The authors associate it - besides alpha-rhythm - also with low frequency theta range and high frequency beta-1. These findings support the idea that both slow and rapid EEG ranges are involved in distant connection of the brain systems into functional dynamic systems, and they also contribute to interaction within local neural nets.