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. Author manuscript; available in PMC: 2013 Nov 4.
Published in final edited form as: Pain. 2008 Jun 6;138(1):10.1016/j.pain.2008.04.018. doi: 10.1016/j.pain.2008.04.018

Fig. 2.

Fig. 2

EMG and behavioral responses to 60-mmHg colorectal distension. (A) Time course of EMG activity 40 s before (baseline) and 40 s after the onset of colorectal distension (CRD). Each data point represents group average of mean amplitude of rectified EMG over a 1-s interval. Data are normalized to average baseline amplitude (defined as 100%). (B) CRD evoked significant increase in EMG activity compared with 0-mmHg controls (267 ± 24% vs. 103 ± 8%, AUC ± SEM, n = 12 for distension group, n = 10 for control, P < 0.0001). Area under curve (EMG-AUC) was computed over the 40 s period after CRD onset and normalized to baseline. (C) CRD evoked significant behavioral responses indicative of visceral pain (77 ± 6% at 60-mmHg vs. 3 ± 3% at 0 mmHg, n = 12 for each group, P < 0.0001). Pain score was computed as the percentage of time the animal spent in postures indicative of visceral pain during the 40 s period after CRD onset. (D) Correlation between EMG-AUC and pain score in the group of animals exposed to 60-mmHg distension (n = 12). EMG-AUC and pain score showed trends of positive correlation without reaching statistical significance (R = 0.469, P = 0.124, Pearson’s correlation coefficient).