Source localization of EEG activity during hypnotically induced anxiety and relaxation

The engagement of different brain regions which implement subjectively expe rienced emotional states in normals is not completely clarified. Emotional states can conveniently be induced by hypnosis-based suggestions. We studie d brain electric activity during hypnotically induced anxiety and relaxatio n in 11 right-handed normals (5 males, 6 females, mean age 26.5 +/- 7.6 yea rs). After induction of light hypnosis, anxiety and then relaxation was sug gested using a standardized text (reverse sequence in half of the subjects) . Nineteen-channel, eyes-closed EEG (20 artifact-free s/subject) was analyz ed (source localization using FFT approximation and low resolution electrom agnetic tomography, LORETA). Global tests revealed the strongest difference (P < 0.005) between EEG source gravity center locations during the two emo tional state?; in the excitatory beta-2 EEG Frequency band (18.5-21 Hz). Po st hoc tests showed that the sources were located more right during anxiety than during relaxation (P = 0.01). LORETA specified that anxiety showed ma ximally stronger activity than relaxation in right Brodmann area 10, and re laxation showed maximally stronger activity than anxiety in left Brodmann a rea 22. Clearly, the two induced emotional states: were associated with act ivity of different neural populations. <)ur results agree with reports on b rain activity shifted to the right (especially fronto-temporal) during nega tive compared with positive emotions, and support the role of beta-2 EEG fr equency in emotional states. (C) 2001 Elsevier Science B.V. All rights rese rved.