Sandra Kamping

Emotional modulation of pain: A clinical perspective.

a Department of Psychosomatic Medicine and Psychotherapy, University of Heidelberg, Central Institute of Mental Health, Mannheim, Germany b Department of Cognitive and Clinical Neuroscience, University of Heidelberg, Central Institute of Mental Health, Mannheim, Germany c Department of Clinical Psychology, Johannes-Gutenberg-University, Mainz, Germany d Institute of Physiology und Pathophysiology, Johannes-Gutenberg-University, Mainz, Germany

Deficient modulation of pain by a positive emotional context in fibromyalgia patients

Summary Fibromyalgia patients show impaired emotion recognition and orientation when positive pictures are presented together with painful stimuli. Treatment approaches should emphasize the normalization of these disrupted emotional processes. ABSTRACT This study aimed to investigate the modulating effects of emotional context on pain perception in 16 patients with fibromyalgia syndrome (FMS) and 16 healthy control (HC) subjects. An infrared laser was used to apply individually adapted painful stimuli to the dorsum of the left hand. The emotional background of the painful stimuli was modulated by concurrent presentations of negative, neutral, and positive picture stimuli selected from the International Affective Picture System. As control conditions, painful stimuli and the pictures were also presented by themselves. During each of the 5 laser‐picture trials, subjects received 10 painful stimuli and were asked to rate the average intensity and unpleasantness of the experienced pain. Functional magnetic resonance images were obtained, using a T2* sensitive echo planar sequence. HC subjects showed a linear increase in pain intensity and unpleasantness ratings when painful stimuli were presented during positive, neutral, and negative pictures. In contrast, FMS patients showed a quadratic trend for pain intensity ratings indicating a lack of pain reduction by the positive pictures. In addition, the FMS patients showed less activation in secondary somatosensory cortex, insula, orbitofrontal cortex, and anterior cingulate cortex during the positive picture pain trials. Our results suggest that fibromyalgia patients are less efficient in modulating pain by positive affect and may benefit less from appetitive events than healthy control subjects.

Cortico-subcortical activation patterns for itch and pain imagery.

Summary This study found the key network important for emotion‐driven covert motor response to itch (ie, scratch) and pain (eg, escape) using fMRI. Abstract The imagery of itch and pain evokes emotional responses and covert motor responses (scratching to itch and withdrawal to pain). This suggests some similarity in cerebral mechanisms. However, itch is more socially contagious than pain, as evidenced by the fact that scratching behaviors can be easily initiated by watching itch‐inducing situations, whereas withdrawal is less easily initiated by watching painful situations. Thus, we assumed that the cerebral mechanisms of itch imagery partly differ from those of pain imagery in particular with respect to motor regions. We addressed this issue in 18 healthy subjects using functional magnetic resonance imaging. The subjects were instructed to imagine itch and pain sensations in their own bodies while viewing pictures depicting stimuli associated with these sensations. Itch and pain imagery activated the anterior insular cortex (aIC) and motor‐related regions such as supplementary motor area, basal ganglia, thalamus, and cerebellum. Activity in these regions was not significantly different between itch and pain imagery. However, functional connectivity between motor‐related regions and the aIC showed marked differences between itch and pain imagery. Connectivity with the aIC was stronger in the primary motor and premotor cortices during pain imagery and stronger in the globus pallidus during itch imagery. These findings indicate that brain regions associated with imagery of itch are the same as those involved in imagery of pain, but their functional networks differ. These differences in brain networks may explain why motor responses to itch are more socially contagious than those related to pain.

An augmented reality home-training system based on the mirror training and imagery approach

Mirror training and movement imagery have been demonstrated to be effective in treating several clinical conditions, such as phantom limb pain, stroke-induced hemiparesis, and complex regional pain syndrome. This article presents an augmented reality home-training system based on the mirror and imagery treatment approaches for hand training. A head-mounted display equipped with cameras captures one hand held in front of the body, mirrors this hand, and displays it in real time in a set of four different training tasks: (1) flexing fingers in a predefined sequence, (2) moving the hand into a posture fitting into a silhouette template, (3) driving a “Snake” video game with the index finger, and (4) grasping and moving a virtual ball. The system records task performance and transfers these data to a central server via the Internet, allowing monitoring of training progress. We evaluated the system by having 7 healthy participants train with it over the course of ten sessions of 15-min duration. No technical problems emerged during this time. Performance indicators showed that the system achieves a good balance between relatively easy and more challenging tasks and that participants improved significantly over the training sessions. This suggests that the system is well suited to maintain motivation in patients, especially when it is used for a prolonged period of time.

The Importance of Synchrony and Temporal Order of Visual and Tactile Input for Illusory Limb Ownership Experiences – An fMRI Study Applying Virtual Reality

In the so-called rubber hand illusion, synchronous visuotactile stimulation of a visible rubber hand together with ones own hidden hand elicits ownership experiences for the artificial limb. Recently, advanced virtual reality setups were developed to induce a virtual hand illusion (VHI). Here, we present functional imaging data from a sample of 25 healthy participants using a new device to induce the VHI in the environment of a magnetic resonance imaging (MRI) system. In order to evaluate the neuronal robustness of the illusion, we varied the degree of synchrony between visual and tactile events in five steps: in two conditions, the tactile stimulation was applied prior to visual stimulation (asynchrony of −300 ms or −600 ms), whereas in another two conditions, the tactile stimulation was applied after visual stimulation (asynchrony of +300 ms or +600 ms). In the fifth condition, tactile and visual stimulation was applied synchronously. On a subjective level, the VHI was successfully induced by synchronous visuotactile stimulation. Asynchronies between visual and tactile input of ±300 ms did not significantly diminish the vividness of illusion, whereas asynchronies of ±600 ms did. The temporal order of visual and tactile stimulation had no effect on VHI vividness. Conjunction analyses of functional MRI data across all conditions revealed significant activation in bilateral ventral premotor cortex (PMv). Further characteristic activation patterns included bilateral activity in the motion-sensitive medial superior temporal area as well as in the bilateral Rolandic operculum, suggesting their involvement in the processing of bodily awareness through the integration of visual and tactile events. A comparison of the VHI-inducing conditions with asynchronous control conditions of ±600 ms yielded significant PMv activity only contralateral to the stimulation site. These results underline the temporal limits of the induction of limb ownership related to multisensory body-related input.

Suffering as an independent component of the experience of pain

Pain has consistently been viewed as containing two dimensions, a sensory (intensity) and an emotional (unpleasantness). It has been suggested that pain involves higher order cognitive processes that go beyond unpleasantness. We therefore aimed at extending the assessment of pain by introducing an additional dimension of pain‐related suffering and identifying noxious stimulation protocols that are most adequate for its psychophysical and psychophysiological characterization.

An MR-compatible device for automated and safe application of laser stimuli in experiments employing nociceptive stimulation.

In this paper the establishment of an automatic laser application device that reproducibly delivers laser stimuli in a safe, controlled, and reliable manner is presented. Nociceptive stimulation is widely used in functional magnetic resonance imaging (fMRI) experiments and a number of different methods are employed. One major advantage of laser stimulation as a method to administer painful stimuli is that it selectively activates nociceptors. To avoid damage to the subjects skin, which might occur if the same skin area were stimulated too often, the laser focal spot needs to be repositioned after each stimulus. Here, we describe the design of the mechanical set-up, the functionality, the computation of laser stimulus intensity, the materials used, the monitoring system, and the interface to the control software. Additionally, MR-compatibility and functionality of the device were evaluated and assessed in a 3T MR scanner. Finally, the reliability and validity of the device were tested and demonstrated. It permits easy and investigator-independent use of laser stimulation in the MR scanner.

The Importance of Ventral Premotor Cortex for Body Ownership Processing

The perception of ones own hand is an eminently coherent impression: proprioceptive, tactile, and visual inputs usually correspond perfectly. Current theoretical frameworks postulate that this multimodal integration is required for a feeling of ownership of the body, and is ultimately accompanied

Assessing suffering in experimental pain models: psychological and psychophysiological correlates

Although suffering is a central issue in pain, there is only little research on this topic. The aim of this study was to assess suffering in an experimental context using various stimulation methods and durations, and to examine which psychological or psychophysiological measures covary with pain-related suffering. Twenty-one healthy volunteers participated in two experiments in which we used tonic thermal and phasic electric stimuli with short and long stimulus durations. The participants rated pain intensity, unpleasantness, and pain-related suffering on separate visual analog scales (VAS) and completed the Pictorial Representation of Illness and Self Measure (PRISM), originally developed to assess suffering in chronic illness. We measured heart rate, skin conductance responses (SCRs), and the electromyogram (EMG) of the musculus corrugator supercilii. For both heat and electric pain, we obtained high ratings on the suffering scale confirming that suffering can be evoked in experimental pain conditions. Whereas pain intensity and unpleasantness were highly correlated, both scales were less highly related to suffering, indicating that suffering is distinct from pain intensity and unpleasantness. Higher suffering ratings were associated with more pronounced fear of pain and increased private self-consciousness. Pain-related suffering was also related to high resting heart rate, increased SCR, and decreased EMG during painful stimulation. These results offer an approach to the assessment of suffering in an experimental setting using thermal and electric pain stimulation and shed light on its psychological and psychophysiological correlates.

The role of cognitive reappraisal in placebo analgesia: an fMRI study

Abstract Placebo analgesia (PA) depends crucially on the prefrontal cortex (PFC), which is assumed to be responsible for initiating the analgesic response. Surprisingly little research has focused on the psychological mechanisms mediated by the PFC and underlying PA. One increasingly accepted theory is that cognitive reappraisal—the reinterpretation of the meaning of adverse events—plays an important role, but no study has yet addressed the possible functional relationship with PA. We studied the influence of individual differences in reappraisal ability on PA and its prefrontal mediation. Participants completed a cognitive reappraisal ability task, which compared negative affect evoked by pictures in a reappraise versus a control condition. In a subsequent fMRI session, PA was induced using thermal noxious stimuli and an inert skin cream. We found a region in the left dorsolateral PFC, which showed a positive correlation between placebo-induced activation and (i) the reduction in participants’ pain intensity ratings; and (ii) cognitive reappraisal ability scores. Moreover, this region showed increased placebo-induced functional connectivity with the periaqueductal grey, indicating its involvement in descending nociceptive control. These initial findings thus suggest that cognitive reappraisal mechanisms mediated by the dorsolateral PFC may play a role in initiating pain inhibition in PA.