A Brief Mindfulness Meditation Training Increases Pain Threshold and Accelerates Modulation of Response to Tonic Pain in an Experimental Study.

OBJECTIVE: Research shows that mindfulness meditation (MM) affects pain perception; however, studies have yet to measure patterns of change over time. We examined effects of MM on perception of experimental heat pain using multiple psychophysical indices, including pattern of change in response to tonic painful stimuli. We also tested the potential moderating role of baseline mindfulness. METHOD: Forty participants were randomly assigned to a brief MM training or control group. We assessed: a) heat pain threshold (HPT), b) temperature which induces pain at a fixed, target intensity level, and c) response pattern over time to tonic heat pain. RESULTS: Compared to control group, the MM group showed increased HPT and more rapid attenuation of pain intensity for tonic pain stimuli. Moderation analyses indicated that baseline mindfulness moderated effects of MM on HPT. CONCLUSIONS: A brief MM intervention appears to affect perception of experimental pain both by increasing pain threshold and accelerating modulation of response. Findings may help elucidate mechanisms of MM for chronic pain.

Do mindfulness-based interventions reduce pain intensity? A critical review of the literature.

BACKGROUND: Mindfulness-based interventions (MBIs) emphasizing a nonjudgmental attitude toward present moment experience are widely used for chronic pain patients. Although changing or controlling pain is not an explicit aim of MBIs, recent experimental studies suggest that mindfulness practice may lead to changes in pain tolerance and pain intensity ratings. OBJECTIVE: The objective of this review is to investigate the specific effect of MBIs on pain intensity. METHODS: A literature search was conducted using the databases PUBMED and PsycINFO for relevant articles published from 1960 to December 2010. We additionally conducted a manual search of references from the retrieved articles. Only studies providing detailed results on change in pain intensity ratings were included. RESULTS: Sixteen studies were included in this review (eight uncontrolled and eight controlled trials). In most studies (10 of 16), there was significantly decreased pain intensity in the MBI group. Findings were more consistently positive for samples limited to clinical pain (9 of 11). In addition, most controlled trials (6 of 8) reveal higher reductions in pain intensity for MBIs compared with control groups. Results from follow-up assessments reveal that reductions in pain intensity were generally well maintained. CONCLUSIONS: Findings suggest that MBIs decrease the intensity of pain for chronic pain patients. We discuss implications for understanding mechanisms of change in MBIs.

Bulbospinal neurons of the rat rostromedial medulla are highly collateralized.

The rostromedial medulla participates in a large variety of sensory, motor, and autonomic functions. We asked whether individual bulbospinal neurons in this region have localized, target-specific terminal arbors or whether they collateralize broadly in the spinal cord. Collateralization was quantified along three spinal axes, rostrocaudal, left-right, and dorsoventral, by using double retrograde labeling. Fluorogold was applied to one target, and cholera toxin B chain (CTB) was applied to the second. We determined the prevalence of neurons that retrogradely label with both tracers in the constituent nuclei of the rostromedial medulla, the raphe nuclei, the gigantocellular reticular nucleus (Gi, bilaterally), the Gi pars alpha (GiA, bilaterally), and the midline medullary reticular formation. A large fraction of neurons in each of these nuclei had bulbospinal projections, ranging from > or =56% for the raphe nuclei to > or =14% for the Gi. For reasons discussed, these values are probably underestimates. Most of the neurons that projected to the lumbar spinal cord also projected to the cervical cord. Likewise, most neurons that projected to the ventral horn also had a collateral branch in the dorsal horn. However, relatively few had bilateral projections; most projected ipsilaterally or contralaterally. A considerable degree of collateralization was also seen among vestibulospinal neurons. The high level of collateralization of the descending projections of the rostromedial medulla suggests that neurons in this area ultimately act on peripheral target tissues or functions that are widely distributed in the body, or that they play a generalized modulatory role across functional modalities, rather than playing specific topographically delimited roles.

"Off with the old": mindfulness practice improves backward inhibition.

Mindfulness practice has been linked to reduced depressive rumination and described as involving inhibition of information that has been relevant in the past and is no longer relevant in the present moment. Backward inhibition (BI) is considered to be one of the purest measures of task set inhibition, and impaired BI has been linked to depressive rumination. BI was contrasted with Competitor Rule Suppression (CRS), which is another phenomenon observed in task switching, yet one which involves episodic memory tagging of information that is currently conflicting rather than active inhibition. Although similar at baseline level, a randomly assigned group (n = 38) who underwent an eight session mindfulness training program exhibited improved BI but not CRS compared to a waiting list group (n = 38). Findings indicate that mindfulness improves the specific component of task set inhibition, which has previously been linked to reduced rumination. Implications regarding the potential role of task set inhibition in mediating between mindfulness and reduced rumination, as well as the role of mindfulness in "being in the present moment" are discussed.

"Mind the trap": mindfulness practice reduces cognitive rigidity.

Two experiments examined the relation between mindfulness practice and cognitive rigidity by using a variation of the Einstellung water jar task. Participants were required to use three hypothetical jars to obtain a specific amount of water. Initial problems were solvable by the same complex formula, but in later problems ("critical" or "trap" problems) solving was possible by an additional much simpler formula. A rigidity score was compiled through perseverance of the complex formula. In Experiment 1, experienced mindfulness meditators received significantly lower rigidity scores than non-meditators who had registered for their first meditation retreat. Similar results were obtained in randomized controlled Experiment 2 comparing non-meditators who underwent an eight meeting mindfulness program with a waiting list group. The authors conclude that mindfulness meditation reduces cognitive rigidity via the tendency to be "blinded" by experience. Results are discussed in light of the benefits of mindfulness practice regarding a reduced tendency to overlook novel and adaptive ways of responding due to past experience, both in and out of the clinical setting.