Objective assessment of cognitive factors involved in visceral perception by using event-related cerebral evoked responses to esophageal target stimulation in man

Evoked potential (EP) studies provide an objective measure of the neural pa thways involved with perception of gastrointestinal stimulation. The effect s of cognitive factors, such as anticipation or awareness, on EP responses are not known. We compared the EP response to esophageal electrical stimula tion with the cortical activity associated with target detection and antici pation of the same stimulus. In 12 healthy men (26.8 +/- 6 years old), esop hageal electrical stimulation (0.2 Hz, 0.2 msec, 15 mA) was applied, and th e EP recorded using scalp electrodes. A computerized model of randomly appl ied target stimuli (1:5 ratio) was used to separately record the EP associa ted with stimulation and the event-related cognitive EP associated with a d ual task-related or anticipated stimulation approach. A periodic electrical stimulus represented the nontarget stimulus and a second electrical impuls e (oddball model) or an omitted stimulus (anticipatory model) the target st imulus. The event-related cognitive EP responses were also compared with st andard and anticipatory auditory P,,, evoked potentials. The esophageal and auditory oddball stimulus approach elicited event-related P300EP in all su bjects. P300EP associated with electrical stimulation had a longer peak lat ency (P < 0.0001) and smaller amplitude than those obtained with auditory s timulation. Anticipatory evoked potentials could be obtained by electrical skipped stimulation in 8 of 12 subjects. These EP were similar to those obt ained with omitted auditory target stimulation, although of significantly s maller amplitude than auditory standard P300EP (P < 0,001). In conclusion, the brain response associated with directed effortful processing of discrim inate esophageal stimuli consists of a large event-related potential (P300E P). Anticipatory stimulation produces a similar event-related cortical resp onse, which is associated with attention to and awareness of the actual sti mulus. The P300EP to gastrointestinal stimuli may provide an objective and powerful electrophysiological tool for the assessment of the cognitive fact ors associated with visceral perception.