Volume 128, Issue 3, Pages 610-619 (March 2005) Real-time imaging of human cortical activity evoked by painful esophageal stimulation  Anthony R. Hobson, Paul L. Furlong, Sian F. Worthen, Arjan Hillebrand, Gareth R. Barnes, Krish D. Singh, Qasim Aziz  Gastroenterology  Volume 128, Issue 3, Pages 610-619 (March 2005) DOI: 10.1053/j.gastro.2004.12.033 Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 1 Stimulation intensity and VAS scores. (A) Values for the stimulus intensity (mA); (B) visual analogue scale (VAS) scores for perceived intensity. Data are given for men, women, and overall for both experimental protocols. Statistical comparisons were made between male and female subjects for MEG vs CEP for stimulus and VAS scores, and no significant differences were seen for any of these comparisons. All values are displayed as group mean ± SD. Gastroenterology 2005 128, 610-619DOI: (10.1053/j.gastro.2004.12.033) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 2 Laterality of cortical activation. This figure shows which cortical hemisphere showed the earliest neural activity as determined from the peak latency of the MEG response. When the latency difference between hemispheres was <5 ms, activation was deemed bilateral. Data reflect both male and female subjects. Gastroenterology 2005 128, 610-619DOI: (10.1053/j.gastro.2004.12.033) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 3 P1 latencies from S1, S2, insula, and cingulate cortices. This figure shows values for the P1 latency of the MEG response from the cortical hemisphere that showed the earliest neural activity. Values are given in milliseconds for male, female, and overall data. Data are displayed as group mean ± SD. Statistical comparison between male and female data showed no significant differences. *Significant increase in the P1 latency from the anterior insula and 3 cingulate regions when compared with somatosensory regions (P = .0001); #significantly decreased latency of the P1 latency from the mid-cingulate when compared with the 2 other cingulate regions when male and female data were pooled (P = .04). Gastroenterology 2005 128, 610-619DOI: (10.1053/j.gastro.2004.12.033) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 4 This figure shows MEG responses from 1 male (left) and 1 female (right) subject taken from representative virtual electrode positions placed in S1, S2, and insula cortices. It can be seen that the first peak (P1, either positive or negative) in the first 4 cortical regions occurs at the same latency. However, the first peak in the anterior insula (bottom trace) has a longer latency. This was consistent for both male and female subjects. Virtual electrode positions are shown via the crosshairs by using a representative anatomic magnetic resonance scan. The scale on the x-axis is in milliseconds, and the y-axis is in nanoampmeters. The black dotted line represents the stimulus onset, and the gray dashed line indicates the approximate first peak (P1) latency. Gastroenterology 2005 128, 610-619DOI: (10.1053/j.gastro.2004.12.033) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 5 This figure shows representative MEG responses from 1 male (left) and 1 female (right) subject taken from representative virtual electrode positions placed in the perigenual (top trace), mid (middle trace), and posterior (bottom trace) cingulate. It can be seen that the first peak (P1, either positive or negative) in these 3 regions occurs at a similar latency. Virtual electrode positions are shown via the crosshairs by using a representative anatomic magnetic resonance scan. The scale on the x-axis is in milliseconds, and the y-axis is in nanoampmeters. The black dotted line represents the stimulus onset, and the gray dashed line indicates the approximate first peak (P1) latency. Gastroenterology 2005 128, 610-619DOI: (10.1053/j.gastro.2004.12.033) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 6 Representative esophageal CEP responses in (A) 2 male and (B) 2 female subjects. All subjects show the characteristic triphasic early CEP complex comprising P1, N1, and P2 peaks. In addition, after these sharply defined peaks, there is a long-duration late response (LR). It is this late response that was not seen in the MEG study from our virtual electrode recordings from specific cortical sites. Gastroenterology 2005 128, 610-619DOI: (10.1053/j.gastro.2004.12.033) Copyright © 2005 American Gastroenterological Association Terms and Conditions