Animal research has elucidated the neurobiological substrates and environmental determinants of pain modulation. Despite these advances, relatively little is known about how psychological processes activate pain modulatory systems. One psychological process that is thought to play an important role in regulating pain sensitivity is emotion. In addition, previous research into the human menstrual cycle and the animal estrous cycle have determined that either the presence of certain gonadal hormones or the fluctuations of these hormones may lead to changes in how females perceive pain, regulate emotion, and modulate pain. The present study examines both the role of emotion and the human menstrual cycle in pain modulation. Participants were 39 female undergraduate students with a mean age of 18.7 years (SD=1.46). Results are consistent with prior studies indicating that progesterone has antiinflammatory effects. Specifically, significant effects were observed primarily in the luteal phase. Subjects in the luteal phase demonstrated less sympathetic arousal during the experiment but greater autonomic arousal during the noise stressor. Participants in the luteal phase also demonstrated an analgesic/anti-inflammatory response evidenced by an observed decrease in secondary hyperalgesia for those that did not receive the noise stressor. No such changes in pain perception were discovered in the ovulation and follicular phases. Finally, in response to the noise stressor, an inhibition of the analgesic/anti-inflammatory effects was observed in the luteal phase. No such evidence of stress-induced pain modulation was discovered in the ovulation and follicular phases. Although the specific mechanisms of this action still remain unclear, prior evidence points to the role of centrally-mediated pain modulation. It is likely that the stressor worked to inhibit the anti-inflammatory effects commonly observed in the luteal phase to persistent inflammatory pain through centrally-mediated pain modulatory mechanisms. It is hypothesized that hormone-mediated effects at the level of the amygdala influenced the impact of affective pain modulation.

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<p>Experiment One: The Effect of Noise on Autonomic Arousal</p><p><br></p><p>In response to the growing demand for research that helps us understand the complex interactions between Autonomic Arousal (AA) on behavior and performance there is an increasing need for robust techniques to efficiently utilize stimuli, such as sound, to vary the level of AA within a study. The goal of this study was to look at the impact of several factors, including sound intensity, order of presentation, and direction of presentation on skin conductance level, a widely utilized technique for approximating levels of AA. To do this we had 34 young adults ages 18- 34 listen to a series of 2-minute blocks of a sound stimuli based off a heating, ventilation, and air conditioning system (HVAC). Blocks included 5 single intensity conditions each block differing in 10 dBA steps ranging from 35-75 dBA. We presented blocks in both rising and falling level of intensity, with half the participants hearing them in a rising order first and half in a falling order first. The evidence found by this study suggests that increasing the sound level plays an important role in increasing AA and habituation is an extremely important factor that must be accounted for as it, in the case of typical young adults, quickly dampens the response to stimuli and subsequent stimuli. These findings suggest that researchers can best efficiently maximize the range of AA they can use while keeping their participants comfortable by starting out with the most intense stimuli and proceeding to the less intense stimuli, working with habitation instead of against it.</p><p> </p><p><br></p><p> Experiment Two: The Effect of Autonomic Arousal on Visual Attention</p><p><br></p><p>The goal of this study was to better understand how various levels of autonomic arousal impact different components of attentional control and if ASD-related traits indexed by Autism Quotient scores (AQ) might relate to alterations in this relationship. This study had 41 young adult participants (23 women, 17 men, 1 prefer not to say), ages ranging from 18 to 38 years old. Participants listened to varying levels of noise to induce changes in AA, which were recorded as changes in skin conductance level (SCL). To evaluate attentional control, participants preformed pro and anti-saccade visual gap–overlap paradigm tasks as measures of attentional control. The findings of this study suggest that increased levels of autonomic arousal are helpful for improving performance on anti-saccade tasks, which are heavily dependent on top-down attentional control. Additionally, increases in AQ scores were related to having less of a benefit from increasing levels of arousal on anti-saccade tasks. Additional interactions were also found and are discussed in this paper.</p>