R.Zimmermann,

Introduction Pain perception is closely related to the attentional level and the vigilance of the subject [4]. The intensity of a pain stimulus and its sensation do often not coincide. A common experimental example is the so-called pain-inhibiting-pain effect: A stressful stimulus, e.g. persistent or chronic pain, often elevates the threshold for brief pain stimuli applied during the same time. Stressful stimuli, which deflects attention from a painful event, may induce the so-called Stress Induced Analgesia [6],[8]. Phasic pain stimuli in the fingertip cause a pin-prick like sensation and lead to a typical activation sequence of the cortex. An activation of the SII region at 100--120 ms which is related to the rational, discriminating component of pain sensation is followed by an activity at 250--350 ms, originating from the cingulate gyrus (CG) which is related to the evaluative perception of pain [9] (for a review, see [1]). This study investigates the change in brain activation