The aim of our study was to characterize brain dynamics of affective modulation of somatosensory processing in chronic pain. We hypothesized that chronic pain patients will show abnormal EEG activity under negative mood conditions compared to healthy controls. Nineteen patients with chronic pain and 21 healthy subjects participated in the experiment. Multiscale entropy, fractal dimension, event-related potentials, and fast Fourier transform were used to analyze EEG data. A significant enhancement of entropy was found in pain patients at P4 compared to P3. Analysis of fractal dimension also revealed significantly higher values at P4 than P3 when pain patients were viewing unpleasant pictures. By contrast, no significant differences due to hemisphere or affective condition were found on nonlinear measures for healthy controls. Analyses of somatosensory ERPs showed that P50 amplitudes elicited by pleasant pictures were more reduced in chronic pain patients than in healthy controls. Finally, we observed that EEG band power was lower in pain patients than in healthy controls, in particular for theta and beta bands over sensorimotor cortices and temporal regions when viewing pleasant images. These findings suggest that sustained pain seems to be accompanied by an abnormal activation and dynamic of brain networks related to emotional processing of somatosensory information in chronic pain. Furthermore, our findings suggest that both linear and nonlinear measures of EEG time series may contribute to the understanding of brain dysfunction in chronic pain.
Etiqueta: multiscale entropy
Fear induced complexity loss in the electrocardiogram of flight phobics: A multiscale entropy analysis
In this study we explored the changes in the variability and complexity of the electrocardiogram (ECG) of flight phobics (N = 61) and a matched non-phobic control group (N = 58) when they performed a paced breathing task and were exposed to flight related stimuli. Lower complexity/entropy values were expected in phobics as compared to controls. The phobic system complexity as well as the heart rate variability (HRV) were expected to be reduced by the exposure to fearful stimuli. The multiscale entropy (MSE) analysis revealed lower entropy values in phobics during paced breathing and exposure, and a complexity loss was observed in phobics during exposure to threatening situations. The expected HRV decreases were not found in this study. The discussion is focused on the distinction between variability and complexity measures of the cardiac output, and on the usefulness of the MSE analysis in the field of anxiety disorders.