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Participation of the Default Mode Network in the Cortical Control of Volitional Swallowing
years) CEPs were assessed by electrical stimulation of anus and rectum at 1cm and 10 cm from anal margin by placing a probe with 2 pairs of bipolar steel ring electrodes. CEP was recorded with scalp electrodes at vertex CZ and reference on right ear lobe. The anal and rectal latencies for CEP responses [P1, N1, P2, N2 (msec)] and their amplitudes [P1-N1, P2-N2 (μV)] were assessed. Data were analyzed and compared using t-test. RESULTS: Table shows mean + SEM for latencies and amplitudes of CEP responses before and after treatment in both the rectum and anus. Dyssynergics had prolonged rectal and anal CEP latency compared to controls. Overall, the latencies decreased (p<0.05) and the amplitude of CEP responses increased (p=ns) showing improved perception and gut-brain neurotransmission following biofeedback therapy. CONCLUSIONS: Both anal and rectal CEPs (afferent gutbrain axis) are attenuated in patients with dyssynergic defecation. Following biofeedback therapy, both rectal and anal CEPs (P1, N1 latency) improved significantly. Biofeedback therapy modulates the neurobiologic gut-brain axis and thereby improves bowel function in dyssynergia. CEP is a novel objective test which provides mechanistic insights on gutbrain function. Acknowledgement: NIH Grant R01 DK057100.
Reliability and Reproducibility of FMRI Activity in the Cortical Swallowing Network Anna Patel, Arash Babaei, Shahryar Ahmad, Andrew S. Nencka, Robert M. Siwiec, Erica A. Samuel, Reza Shaker Background & Aim: Early studies using functional MRI (fMRI) have demonstrated that volitional swallow is associated with activation of a number of cortical areas (middle cingulate gyrus, ventrolateral prefrontal cortex, ventrolateral sensory/motor cortices and middle insula), which collectively represent the “cortical swallowing network” (CSN). Although the activation of these regions has been reported in the literature, the reproducibility of these activations has not been systematically studied. The aim of our study is to investigate the reproducibility of the CSN across different fMRI sessions. Methods: We studied 16 young right-handed healthy volunteers utilizing a standard paradigm driven fMRI protocol and analyzed with an event-related analysis technique. Echo-planar images were obtained during two identical nine minute scans across different sessions while twenty-one dry swallows were performed by visual cues in random intervals. Physiologic circulatory and respiratory-related signal changes were removed retrospectively. Functional images were then aligned, registered (12 degrees of freedom), and mapped stereotaxically to the standard coordinate system. Generalized linear model was then used to remove undesirable signal changes correlated with motion, white matter and cerebrospinal fluid. Finally, the second order group random mixed-effect multilevel analysis was performed to identify active cortical regions. Clusters with p<0.01 corrected for multiple comparisons were considered significant. The number of activated voxels (3.75x3.75x4 mm3) along with their average and peak percent signal change within each cluster was reported and compared between the two study sessions in order to determine the correlation co-efficient. Results: All subjects showed significant and clustered activity within the deglutition network during both scans. Activity within the right precuneus and supplementary area were not reproducible. Overall, the percent fMRI signal change and the number of activated voxels were similar between the two studies with correlation co-efficients r=0.88 and r=0.86, respectively (p<0.0001). Activity within the right precuneus and supplementary area were not reproducible. Within the remaining 20 regions of interest (ROI), the overlap of activity maps across both sessions showed that the center of the activated clusters was within 6.3±4.8 mm (less than two voxels). The difference in maximum activated voxel activity was 9.7±5.9 mm. Conclusions: fMRI activity maps as well as percent signal change and number of voxels activated by volitional swallow in the CSN are reproducible between studies.
* p<0.05, Before vs After Treatment; † p<0.05, Before Treatment vs Healthy Controls; ‡ p<0.05, After Treatment vs Healthy Controls Sa2008 Participation of the Default Mode Network in the Cortical Control of Volitional Swallowing Arash Babaei, Shahryar Ahmad, Anna Patel, Andrew S. Nencka, Reza Shaker Background & Aim: Simultaneous direct neuronal recordings in conjunction with functional magnetic resonance imaging (fMRI) in primates have suggested that the negative blood oxygenation level dependent (BOLD) response correlates with cortical active neuronal inhibition. Certain regions of the brain, namely the posterior cingulate cortex, medial prefrontal cortex, hippocampal formation and lateral parietal cortex consistently demonstrate negative BOLD activity during a variety of goal-directed task conditions. This network has been named “task negative” or “default mode” network. The function of the positive BOLD signal in the swallow network has been investigated; however, the negative BOLD activity in visceral functions such as deglutition has not been systematically studied. The aim of our study was to identify negative BOLD regions during volitional swallow and compare that to the default mode network. Methods: We studied 16 young healthy volunteers utilizing a standard paradigm driven fMRI protocol and analyzed with an event-related analysis technique as reported previously. Second order group random mixed-effect multilevel analysis was then performed on individually identified activated cortical regions. Clusters with p<0.01 corrected for multiple comparisons were reported to be significant. Results: The positive BOLD activity was observed in the following previously reported regions of the swallow network: the middle cingulate gyrus, ventrolateral prefrontal cortex, ventrolateral sensory/motor cortices and middle insula. Negative BOLD activity during swallow involved the medial anterior prefrontal, anterior and posterior cingulate cortices, as well as the dorsolateral prefrontal and lateral parietal cortex. We found that these regions were remarkably similar and their coordinates overlapped with the previously described “default mode network” in non-visceral sensory-motor cognitive tasks. Conclusion: Volitional swallowing is centrally controlled by two distinct networks, one exhibiting positive BOLD indicating neuronal activity of certain regions collectively known as the swallow network and the other exhibiting negative BOLD signals indicating neuronal inhibition of other specific regions collectively representing the default mode network.
Number of activated positive BOLD voxels and corresponding peak and average signal intensity change in cortical swallowing network across different sessions. Stereotaxic locations of the center and peak active voxel within clusters are shown in the Talairach-Tournoux system along with Brodmann areas and sub-regions of each cluster.
Sa2009 Esophageal Acid Exposure Alters the Functional Connectivity of the Deglutition Network Robert M. Siwiec, Arash Babaei, Shahryar Ahmad, B. Douglas Ward, Wenjun Li, Shi-Jiang Li, Reza Shaker
Sa2007 Does Biofeedback Therapy Modulate Anorectal (Gut)-Brain Axis in Patients With Dyssynergic Defecation? Satish S. Rao, Kasaya Tantiphlachiva, Jose Remes-Troche, Ashok Attaluri, Jessica Valestin, Gregory Cheeney, Shaheen Hamdy
Background: Resting state functional connectivity has emerged as an important technique to study the neuronal networks of the brain. Differences in functional connectivity have been shown in various physiologic and pathologic conditions. Swallowing activates a number of cortical areas that together represent the deglutition network. Previous studies have shown that subliminal esophageal acid stimulation has a potentiating effect on cortical subregions active during volitional swallowing in healthy individuals. The resting state functional connectivity of the deglutition network during esophageal perfusion has not been systematically evaluated. The aim of the present study was to test the hypothesis that functional connectivity within the swallowing network can be altered by esophageal acid exposure. Methods: Fourteen right-handed, healthy volunteers (24 + 4, 7F) underwent fMRI scanning during 9 minute runs in each of the following conditions: a) pre-infusion b) buffer infusion c) 0.1N
INTRODUCTION: Patients with dyssynergic defecation exhibit alterations in sensori-motor function and gut-brain axis. Whether these changes are due to the underlying problem and whether they improve with biofeedback therapy is not known. Also, the neurobiologic mechnism(s) by which biofeedback improves dyssynergic constipation is unknown. AIMS: To investigate the afferent anorectal-brain axis by examining the rectal and anal cortical evoked potentials (CEP), before and after biofeedback therapy in subjects with dyssynergic defecation and to compare with healthy controls. METHODS: In 42 subjects with dyssynergic defecation (M/F 2/40, mean age 40 years) and 26 healthy controls (M/F 8/18, mean age 39
S-367
AGA Abstracts
AGA Abstracts
Sa2006
Reliability and Reproducibility of FMRI Activity in the Cortical Swallowing Network Anna Patel, Arash Babaei, Shahryar Ahmad, Andrew S. Nencka, Robert M. Siwiec, Erica A. Samuel, Reza Shaker Background & Aim: Early studies using functional MRI (fMRI) have demonstrated that volitional swallow is associated with activation of a number of cortical areas (middle cingulate gyrus, ventrolateral prefrontal cortex, ventrolateral sensory/motor cortices and middle insula), which collectively represent the “cortical swallowing network” (CSN). Although the activation of these regions has been reported in the literature, the reproducibility of these activations has not been systematically studied. The aim of our study is to investigate the reproducibility of the CSN across different fMRI sessions. Methods: We studied 16 young right-handed healthy volunteers utilizing a standard paradigm driven fMRI protocol and analyzed with an event-related analysis technique. Echo-planar images were obtained during two identical nine minute scans across different sessions while twenty-one dry swallows were performed by visual cues in random intervals. Physiologic circulatory and respiratory-related signal changes were removed retrospectively. Functional images were then aligned, registered (12 degrees of freedom), and mapped stereotaxically to the standard coordinate system. Generalized linear model was then used to remove undesirable signal changes correlated with motion, white matter and cerebrospinal fluid. Finally, the second order group random mixed-effect multilevel analysis was performed to identify active cortical regions. Clusters with p<0.01 corrected for multiple comparisons were considered significant. The number of activated voxels (3.75x3.75x4 mm3) along with their average and peak percent signal change within each cluster was reported and compared between the two study sessions in order to determine the correlation co-efficient. Results: All subjects showed significant and clustered activity within the deglutition network during both scans. Activity within the right precuneus and supplementary area were not reproducible. Overall, the percent fMRI signal change and the number of activated voxels were similar between the two studies with correlation co-efficients r=0.88 and r=0.86, respectively (p<0.0001). Activity within the right precuneus and supplementary area were not reproducible. Within the remaining 20 regions of interest (ROI), the overlap of activity maps across both sessions showed that the center of the activated clusters was within 6.3±4.8 mm (less than two voxels). The difference in maximum activated voxel activity was 9.7±5.9 mm. Conclusions: fMRI activity maps as well as percent signal change and number of voxels activated by volitional swallow in the CSN are reproducible between studies.
* p<0.05, Before vs After Treatment; † p<0.05, Before Treatment vs Healthy Controls; ‡ p<0.05, After Treatment vs Healthy Controls Sa2008 Participation of the Default Mode Network in the Cortical Control of Volitional Swallowing Arash Babaei, Shahryar Ahmad, Anna Patel, Andrew S. Nencka, Reza Shaker Background & Aim: Simultaneous direct neuronal recordings in conjunction with functional magnetic resonance imaging (fMRI) in primates have suggested that the negative blood oxygenation level dependent (BOLD) response correlates with cortical active neuronal inhibition. Certain regions of the brain, namely the posterior cingulate cortex, medial prefrontal cortex, hippocampal formation and lateral parietal cortex consistently demonstrate negative BOLD activity during a variety of goal-directed task conditions. This network has been named “task negative” or “default mode” network. The function of the positive BOLD signal in the swallow network has been investigated; however, the negative BOLD activity in visceral functions such as deglutition has not been systematically studied. The aim of our study was to identify negative BOLD regions during volitional swallow and compare that to the default mode network. Methods: We studied 16 young healthy volunteers utilizing a standard paradigm driven fMRI protocol and analyzed with an event-related analysis technique as reported previously. Second order group random mixed-effect multilevel analysis was then performed on individually identified activated cortical regions. Clusters with p<0.01 corrected for multiple comparisons were reported to be significant. Results: The positive BOLD activity was observed in the following previously reported regions of the swallow network: the middle cingulate gyrus, ventrolateral prefrontal cortex, ventrolateral sensory/motor cortices and middle insula. Negative BOLD activity during swallow involved the medial anterior prefrontal, anterior and posterior cingulate cortices, as well as the dorsolateral prefrontal and lateral parietal cortex. We found that these regions were remarkably similar and their coordinates overlapped with the previously described “default mode network” in non-visceral sensory-motor cognitive tasks. Conclusion: Volitional swallowing is centrally controlled by two distinct networks, one exhibiting positive BOLD indicating neuronal activity of certain regions collectively known as the swallow network and the other exhibiting negative BOLD signals indicating neuronal inhibition of other specific regions collectively representing the default mode network.
Number of activated positive BOLD voxels and corresponding peak and average signal intensity change in cortical swallowing network across different sessions. Stereotaxic locations of the center and peak active voxel within clusters are shown in the Talairach-Tournoux system along with Brodmann areas and sub-regions of each cluster.
Sa2009 Esophageal Acid Exposure Alters the Functional Connectivity of the Deglutition Network Robert M. Siwiec, Arash Babaei, Shahryar Ahmad, B. Douglas Ward, Wenjun Li, Shi-Jiang Li, Reza Shaker
Sa2007 Does Biofeedback Therapy Modulate Anorectal (Gut)-Brain Axis in Patients With Dyssynergic Defecation? Satish S. Rao, Kasaya Tantiphlachiva, Jose Remes-Troche, Ashok Attaluri, Jessica Valestin, Gregory Cheeney, Shaheen Hamdy
Background: Resting state functional connectivity has emerged as an important technique to study the neuronal networks of the brain. Differences in functional connectivity have been shown in various physiologic and pathologic conditions. Swallowing activates a number of cortical areas that together represent the deglutition network. Previous studies have shown that subliminal esophageal acid stimulation has a potentiating effect on cortical subregions active during volitional swallowing in healthy individuals. The resting state functional connectivity of the deglutition network during esophageal perfusion has not been systematically evaluated. The aim of the present study was to test the hypothesis that functional connectivity within the swallowing network can be altered by esophageal acid exposure. Methods: Fourteen right-handed, healthy volunteers (24 + 4, 7F) underwent fMRI scanning during 9 minute runs in each of the following conditions: a) pre-infusion b) buffer infusion c) 0.1N
INTRODUCTION: Patients with dyssynergic defecation exhibit alterations in sensori-motor function and gut-brain axis. Whether these changes are due to the underlying problem and whether they improve with biofeedback therapy is not known. Also, the neurobiologic mechnism(s) by which biofeedback improves dyssynergic constipation is unknown. AIMS: To investigate the afferent anorectal-brain axis by examining the rectal and anal cortical evoked potentials (CEP), before and after biofeedback therapy in subjects with dyssynergic defecation and to compare with healthy controls. METHODS: In 42 subjects with dyssynergic defecation (M/F 2/40, mean age 40 years) and 26 healthy controls (M/F 8/18, mean age 39
S-367
AGA Abstracts
AGA Abstracts
Sa2006