Previous experiments found that placebos produced small decreases in neural activity of pain-related areas of the brain, yet decreases were only statistically significant after termination of stimuli and in proximity to when subjects rated them. These changes could reflect report bias rather than analgesia. This functional magnetic resonance imaging (fMRI) study examined whether placebo analgesia is accompanied by reductions in neural activity in pain-related areas of the brain during the time of stimulation. Brain activity of irritable bowel syndrome patients was measured in response to rectal distension by a balloon barostat. Large reductions in pain and in brain activation within pain-related regions (thalamus, somatosensory cortices, insula, and anterior cingulate cortex) occurred during the placebo condition. Results indicate that decreases in activity were related to placebo suggestion and a second factor (habituation/attention/conditioning). Although many factors influence placebo analgesia, it is accompanied by reduction in pain processing within the brain in clinically relevant conditions.

Temporal summation of "second pain" (TSSP) is considered to be the result of C-fiber-evoked responses of dorsal horn neurons, termed 'windup'. This phenomenon is dependent on stimulus frequency (0.33 Hz) and relevant for central sensitization and chronic pain. Previous brain imaging studies have only been used to characterize neural correlates of second pain but not its temporal summation. We utilized functional magnetic resonance imaging (fMRI) in healthy volunteers to measure brain responses associated with TSSP. Region of interest analysis was used to assess TSSP related brain activation. Eleven pain-free normal subjects underwent fMRI scanning during repetitive heat pulses to the right foot at 0.33 and 0.17 Hz. Stimulus intensities were adjusted to each individual's heat sensitivity to achieve comparable TSSP ratings of moderate pain in all subjects. As predicted, experimental pain ratings showed robust TSSP during 0.33 Hz but not 0.17 Hz stimuli. fMRI statistical maps identified several brain regions with stimulus and frequency dependent activation consistent with TSSP, including contralateral thalamus (THAL), S1, bilateral S2, anterior and posterior insula (INS), mid-anterior cingulate cortex (ACC), and supplemental motor areas (SMA). TSSP ratings were significantly correlated with brain activation in somatosensory areas (THAL, S1, left S2), anterior INS, and ACC. These results show that neural responses related to TSSP are evoked in somatosensory processing areas (THAL, S2), as well as in multiple areas that serve other functions related to pain, such as cognition (ACC, PFC), affect (INS, ACC, PAG), pre-motor activity (SMA, cerebellum), and pain modulation (rostral ACC).

Objective. To define patient-determined success criteria for fibromyalgia and back pain treatment across four outcome domains: pain, fatigue, emotiona

Summary: The main objective of the present study was to examine daily associations (intraindividual variability or IIV) between sleep and affect in older adults. Greater understanding of these associations is important, because both sleep and affect represent modifiable behaviors that can have a major influence on older adults’ health and well‐being. We collected sleep diaries, actigraphy, and affect data concurrently for 14 days in 103 community‐dwelling older adults. Multilevel modeling was used to assess the sleep–affect relationship at both the group (between‐persons) and individual (within‐person or IIV) levels. We hypothesized that nights characterized by better sleep would be associated with days characterized by higher positive affect and lower negative affect, and that the inverse would be true for poor sleep. Daily associations were found between affect and subjective sleep, only and were in the hypothesized direction. Specifically, nights with greater reported awake time or lower sleep quality ratings were associated with days characterized by less positive affect and more negative affect. Gender was not a significant main effect in the present study, despite previous research suggesting gender differences in the sleep–affect relationship. The fact that self‐ratings of sleep emerged as the best predictors of affect may suggest that perceived sleep is a particularly important predictor. Finally, our results suggest exploration of affect as a potential intervention target in late‐life insomnia is warranted.