Dowman R
Department of Psychology, Clarkson University, Potsdam, NY 13699-5825, USA.
Psychophysiology. 2001 May;38(3):451-64.
The effects of attentional set on subjective magnitude ratings, spinal reflexes, and somatosensory evoked potentials (SEP) elicited by innocuous and painful sural nerve stimulation were investigated in 24 subjects. Cuing stimuli informed subjects as to whether a visual identification or a somatosensory rating task would follow. Twenty percent of the trials were invalidly cued, where the subjects were expecting a visual stimulus but were given a sural nerve stimulus and vice versa. Subjective magnitude ratings were lower in the invalidly cued condition than the validly cued condition. Attentional set had no effect on innocuous-related spinal or early cortical responses, nor on the spinal nociceptive withdrawal reflex. The pain-related negative difference potential (NDP) and P2 component of the SEP were largest in the invalidly cued condition. These results provide further support for our hypothesis that the NDP is generated in part by the anterior cingulate, and suggest that the anterior cingulate response to pain reflects non-pain-specific cognitive processes (e.g., orienting attention towards important stimuli in the environment and/or response competition) and not some aspect of the pain experience. The effects of attentional set on the pain-related P2 suggests that it might correspond to the P3a event-related potential. If this is the case, the pain-related P2 could serve as a useful index of neural processes involved in the cognitive-evaluative aspect of pain.
我们对24名受试者进行了研究，以探讨注意力定势对无害及疼痛性腓肠神经刺激所引发的主观强度评级、脊髓反射和体感诱发电位（SEP）的影响。提示刺激会告知受试者随后将进行视觉识别任务还是体感评级任务。20%的试验提示无效，即受试者预期会接受视觉刺激时却给予了腓肠神经刺激，反之亦然。在提示无效的情况下，主观强度评级低于提示有效的情况。注意力定势对与无害刺激相关的脊髓或早期皮层反应以及脊髓伤害性退缩反射均无影响。在提示无效的情况下，SEP中与疼痛相关的负向差异电位（NDP）和P2成分最大。这些结果进一步支持了我们的假设，即NDP部分由前扣带回产生，并表明前扣带回对疼痛的反应反映的是非疼痛特异性认知过程（例如，将注意力导向环境中的重要刺激和/或反应竞争），而非疼痛体验的某些方面。注意力定势对与疼痛相关的P2的影响表明，它可能与P3a事件相关电位相对应。如果是这样，与疼痛相关 的P2可作为疼痛认知评估方面所涉及神经过程的有用指标。
