Our subjective sensory experiences are thought to be heavily shaped by interactions between expectations and incoming sensory information. However, the neural mechanisms supporting these interactions remain poorly understood. By using combined psychophysical and functional MRI techniques, brain activation related to the intensity of expected pain and experienced pain was characterized. As the magnitude of expected pain increased, activation increased in the thalamus, insula, prefrontal cortex, anterior cingulate cortex (ACC) and other brain regions. Pain-intensityrelated brain activation was identified in a widely distributed set of brain regions but overlapped partially with expectation-related activation in regions, including the anterior insula and ACC. When expected pain was manipulated, expectations of decreased pain powerfully reduced both the subjective experience of pain and activation of pain-related brain regions, such as the primary somatosensory cortex, insular cortex, and ACC. These results confirm that a mental representation of an impending sensory event can significantly shape neural processes that underlie the formulation of the actual sensory experience and provide insight as to how positive expectations diminish the severity of chronic disease states.functional MRI ͉ mental imagery ͉ placebo ͉ psychophysical T he experience of a sensory event is highly subjective and can vary substantially from one individual to the next (1). Much of this individual variation may result from the manner in which past experience and future predictions about a stimulus are used to interpret afferent information. Consistent pairing of environmental cues with sensory events provides a learned historical context that is critically important for the prediction and processing of future sensations (2, 3). However, expectations that are inconsistent with sensory information can dramatically alter the sensory experience. In the case of pain, positive expectations can powerfully reduce the subjective experience of pain evoked by a consistently noxious stimulus, whereas negative expectations may result in the amplification of pain (4-7). Furthermore, expectations in which there is a high degree of certainty as to the outcome may activate descending control systems to diminish pain, whereas expectations associated with uncertain outcomes may amplify pain (8).The prefrontal cortex (PFC), anterior insula, and anterior cingulate cortex (ACC) are activated during the anticipation of pain, but their exact role in pain expectation remains poorly delineated (9-12). Moreover, the neural mechanisms by which conscious predictions about the magnitude of pain influence the experience of pain remain poorly understood and largely unexploited in the treatment of pain. At the most fundamental level, expectation-induced modulation of pain must necessarily engage three neural processes. First, an active mental representation of an impending event must be formulated by incorporating past information with the present context and future implica...

After thoracotomy, patients often suffer from a persistent pain syndrome called post-thoracotomy pain. To elucidate morbidity, time course, and predictive factors for this syndrome, we analyzed follow-up data for 85 post-thoracotomy patients. We used a four-point scale to assess pain: none, slight, moderate and severe. Of 85 patients, 50 reported pain (39 slight, 11 moderate) one day after surgery. A year after surgery, the patients were polled using a simple questionnaire received by the mail. Sixty patients reported persistent pain (34 slight, 14 moderate, 12 severe) a month after surgery, and 35 patients reported persistent pain (33 slight, two moderate) around the time of the poll (1 year after surgery). Although pain deterioration was observed in 40% (34/85) of patients during month 1 after surgery, pain alleviation was seen in 48% (41/85) of patients during months 2-12. Stepwise regression analysis revealed that female gender and pain at postoperative day 1 were predictive for persistent pain both 1 month and 1 year after thoracotomy. Among 35 patients with persistent pain 1 year after surgery, 24 cases reported paresthesia-dysesthesia, and 14 cases reported hypoesthesia. The present data thus suggests that persistent pain is common and often severe 1 month after surgery but is alleviated after 1 year. Clinical time course and symptoms indicate that nerve impairment rather than simple nociceptive impact may be involved in this syndrome.

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Since the anterior cingulate cortex (ACC) is known to be involved both in nociception and in anticipation that precedes the avoidance of aversive stimuli, the linking of these functions may be processed in the ACC. To test this hypothesis, we recorded single neuronal activities in the ACC of a macaque monkey while it was performing a pain-avoidance task and examined them with nociceptive cutaneous electric stimuli (ES). Thirty-six neurons responded in anticipation of the ES. Of these, 22 neurons were tested with the ES and 11 responded. These neurons could be those that are involved both in nociception and in pain anticipation that precedes the avoidance of noxious stimuli.

Our results suggest that dailyhigh-frequency rTMS of the ipsilesional M1 is tolerable and modestly facilitates motor recovery in the paralytic hand of subacute stroke patients.

BackgroundGait abnormalities in the elderly, characterized by short steps and frozen gait, can be caused by several diseases, including idiopathic normal pressure hydrocephalus (INPH), and Parkinson’s disease (PD). We analyzed the relationship between these two conditions and their association with gait abnormalities using laboratory test data and findings from diffusion tensor imaging (DTI).MethodsThe study involved 10 patients with INPH, 18 with PD, and 10 healthy individuals (control group). Fractional anisotropy (FA) of five brain areas was measured and compared among the three groups. In addition, the association of INPH and PD with gait capability, frontal lobe function, and FA of each brain area was evaluated.ResultsThe INPH group had significantly lower FA for anterior thalamic radiation (ATR) and forceps minor (Fmin) as compared to the PD group. The gait capability correlated with ATR FA in the INPH and PD groups. We found that adding DTI to the diagnosis assisted the differential diagnosis of INPH from PD, beyond what could be inferred from ventricular size alone.ConclusionsWe expect that DTI will provide a useful tool to support the differential diagnosis of INPH and PD and their respective severities.

Pain is a temporally dynamic experience. Yet, in most instances, pain ratings are acquired in a static fashion and frequently require subjects to retrospectively evaluate the pain experience that occurred in a preceding interval of time. In order to determine which components of the real-time experience of pain contribute to static pain ratings, we obtained real-time (dynamic) and post-stimulus (static) ratings using a visual analogue scale during various of durations (5-30 s) of noxious thermal stimulation (43-49 degrees C). For both pain-intensity and pain-unpleasantness, real-time ratings revealed that pain adapted when stimulus temperatures were low to moderate and summated when stimulus temperature was high. Regression analyses examining both pain-intensity and pain-unpleasantness revealed that the mean response and the peak response of real-time ratings significantly contributed to post-stimulus ratings, while temporal components such as perceived duration of pain contributed minimally. Additional regression analyses revealed that mean and peak responses of real-time intensity ratings accounted for much of the variability of post-stimulus unpleasantness ratings whereas real-time unpleasantness ratings accounted for somewhat less of the variability of post-stimulus intensity ratings. Taken together, the close relationship between real-time and post-stimulus ratings of pain across stimulus conditions evoking both adaptation and temporal summation further confirms that post-stimulus, retrospective ratings of pain are valid measures of the real-time experience of pain.

Our results confirmed the long-term effects of the transfer package in constraint-induced movement therapy.