INVESTIGATION OF THE REPRODUCIBILITY OF CEREBRAL ACTIVITY TO OESOPHAGEAL STIMULATION.

Introduction: The cerebral activation during functional magnetic resonance imaging (fMRI) sessions can be influenced by many variables including scanner noise, subject movement, and cognition, such as habituation and learning. Although the cerebral processing of visceral sensation has been studied, information regarding the trial re-trail reliability is not available. Aims: The purpose of this study was to assess the reproducibility of the functional neural correlates of oesophageal sensation, using fMRI. Methods: 7 healthy volunteers participated in the studv. The protocol consisted of two conditions; non-painful (50% of the difference between sensory and pain thresholds) and painful (pain threshold) stimulation intensities using phasic balloon distension in the distal oesophagus. The order of presentation of these intensities was counterbalanced. A mod fled block design was employed for each intensity where "active" and "rest" phases were repeated five times. This experimental procedure was repeated on two additional occasions (three scans in total) to investigate the consistency of cerebral activation over time. Results: In response to painful stimulation highly reproducible activation was seen in the anterior cingulate gyrus (ACG) (BA24, 32), bilateral insula, supplementary motor cortex (SMA), thalamus, primary and secondary sensory cortices (SI&SII) and dorsolateral prefrontal cortex. Further analysis revealed a significant (p < 0.05) decrease in cerebral activity from the first to the final scan in the interior cingulate (ACG), SMA and SI. Activation in response to non-painful stimulation was seen in similar regions to those seen during painful stimulation. with the exception of the thalamus, but was found to be more variable in the ACC, SI, SII, and SMA in comparison to painful stimulation. Conclusions: Painful stimulation of the oesophagus produces robust activity in many brain regions previously associated with visceral pain. Non-painful... [ABSTRACT FROM AUTHOR]