Electrophysiological correlates of anxious rumination.

EEG coherence and EEG power response were recorded as 63 participants engaged in one of three experimental conditions: 'personal rumination', 'nominal rumination', and 'baseline counting'. The rumination conditions were separated by a neutral (counting) task to eliminate neural carry-over effects. For personal rumination, participants spent 2 min ruminating about something in their life about which they were in two minds (i.e., in a state of personal conflict). For nominal rumination, they were presented with a conflict scenario (concerning buying a car) and instructed to ruminate about that for 2 min. The baseline counting task simply involved counting forwards from 1 at a speed comfortable to the individual. Participants completed various questionnaires to measure mood and also traits of personality (including trait anxiety). EEG data were analysed in the following wavebands: 4-6 Hz, 6-8 Hz, 8-10 Hz, 10-12 Hz, 12-20 Hz and 20-30 Hz. Results revealed that the scalp-wide EEG theta (4-6 Hz and 6-8 Hz) coherence associated with personal rumination was significantly greater than that associated with nominal rumination and baseline counting. Similarly, the scalp-wide 6-8 Hz and parietal-occipital 4-6 Hz power associated with personal rumination were significantly greater than power associated with the nominal rumination and power for baseline counting. For alpha, the 10-12 Hz scalp-wide EEG coherence associated with personal rumination was significantly greater than that associated with baseline counting. Otherwise, the scalp-wide 10-12 Hz power related to both nominal rumination and personal rumination were significantly greater than in response to baseline counting. For 20-30 Hz scalp-wide EEG power, data in response to the nominal rumination condition were significantly increased compared to data associated with the baseline counting condition. In terms of questionnaire data, tense arousal, anger/frustration, hedonic tone and energetic arousal were all influenced by rumination. This was largely in line with expectation. Also, mood state was influenced by neuroticism and state anxiety. Our EEG results are consistent with Gray and McNaughton's [Gray, J.A., McNaughton, N., 2000. The neuropsychology of Anxiety: An Anquiry into the Functions of the Septo-Hippocampal System. 2nd ed. Oxford University Press, Oxford.] account of recursive processing between the septo-hippocampal system and neocortex during goal-conflict resolution inherent in rumination. Evidence of posterior cingulate involvement in this processing was also discussed. Recommendations for future research, aimed at further evaluating the role of the SHS and the posterior cingulated, were outlined. Effects found in alpha were linked to increased vigilance whilst effects in beta were linked to cognitive and emotional aspects of the task. We conclude that these data provide new information of the neural processes associated with the psychological state of anxious rumination and, thus, hold implications for understanding normal and pathological anxiety.