(646)

Our laboratory has shown that emotion modulates spinal nociception and pain resulting from unpredictable noxious shocks. However, unpredictable aversive events have been shown to increase negative affect; therefore, it is unclear what effect this may have on our experimental paradigm. To examine this issue, the present study examined the influence of emotion on pain and spinal nociception (nociceptive flexion reflex, NFR) resulting from predictable or unpredictable noxious shocks to the sural nerve. To induce emotion, 24 emotionally-charged pictures (threat, neutral, & erotic) were presented in random order and shocks were delivered during and in between pictures. NFR amplitudes and pain from shocks were recorded. For half of the participants (n=25) shocks were always preceded by a cue (predictable), the others (n=25) received no cue (unpredictable). Manipulation checks verified that emotion was successfully induced by picture-viewing. Erotic pictures increased positive emotion and threat pictures increased negative emotion. Irrespective of predictability, pain was always inhibited by positive emotion and enhanced by negative emotion. However, emotional modulation of spinal nociception was moderated by shock predictability. When shocks were unpredictable, spinal nociception (NFR) was modulated in parallel with pain ratings. However, when shocks were predictable, the NFR was unaffected by emotion – an effect that was not due to complete inhibition of the NFR because the NFR was still observed. However, during predictable shocks the NFR did not covary with emotion. These data replicate our prior work demonstrating that emotion can engage descending modulation of spinal nociception when shocks are unpredictable. Extending that research, this study suggests that emotional modulation of spinal nociception is abolished when the noxious stimulus is unpredictable. Subjective pain is modulated by emotion irrespective of predictability. These data imply that separate mechanisms are responsible for emotional modulation of spinal nociception and evaluative pain, and predictability disengages modulation at spinal levels.