Classical conditioned response of rectosigmoid motility and regional cerebral activity in humans

The relationship between the central processes of classical conditioning and conditioned responses of the gastrointestinal function is incompletely understood in humans. We tested the hypothesis that the rectosigmoid motility becomes conditioned with anticipatory painful somatosensory stimulus and that characteristic brain areas become activated during anticipation. In nine right-handed healthy male subjects, a loud buzzer (CS, conditional stimulus) was paired with painful transcutaneus electrical nerve stimulation to the right hand (unconditional stimulus). Rectosigmoid muscle tone measured by the barostat as the intrabag volume, phasic contractions of the bowel measured as the number of phasic volume events (PVEs), and regional cerebral blood flow assessed by positron emission tomography (PET), were measured before and after conditioning. Following conditional trials, the bag volume after CS alone did not show significant changes between before and after the stimulus, but the number of PVEs after 2-minute interval of the CS alone was significantly greater than that before the stimulus (P < 0.05). The PET data showed the conditioning elicited significant cerebral activation of the prefrontal, anterior cingulate, parietal and insula cortices (P

在人类中，经典条件反射的中枢过程与胃肠功能的条件反射之间的关系尚未完全了解。我们验证了这样一个假设：直肠乙状结肠的运动因预期的疼痛性躯体感觉刺激而形成条件反射，并且在预期过程中特定的大脑区域会被激活。在9名右利手的健康男性受试者中，一个响亮的蜂鸣器（条件刺激，CS）与右手的经皮电神经刺激疼痛（非条件刺激）相结合。在条件反射前后，测量了通过恒压器测量的直肠乙状结肠肌张力（以袋内体积表示）、以阶段性容积事件（PVE）数量表示的肠道阶段性收缩，以及通过正电子发射断层扫描（PET）评估的局部脑血流。在条件试验之后，仅CS后的袋内体积在刺激前后没有显示出显著变化，但仅CS后2分钟间隔的PVE数量显著大于刺激前（P < 0.05）。PET数据显示，条件反射引起了前额叶、前扣带回、顶叶和脑岛皮质的显著大脑激活（P