1,721,086 research outputs found
Open your mind to placebo conditioning
No full textThis invited Editorial briefly reviews available evidence about the key role of learning and of prefrontal regions in placebo analgesia. These findings have potentially strong clinical implications, because placebo effects can overlap those of drugs and of other therapeutic approaches
Functional imaging and pain: behavior, perception, and modulation
No full textTime-dependent increases of local metabolic or blood flow rates have been described in spinal cord and brain nociceptive networks during acute and chronic pain states in experimental animals, in parallel with changes of different behavioral endpoints of pain and hyperalgesia. In healthy human volunteers, pain intensity-related hemodynamic changes have been identified in a widespread, bilateral brain system including parietal, insular, cingulate and frontal cortical areas, as well as thalamus, amygdala and midbrain, during different kinds of acute noxious stimulation. Specific patterns of nociceptive activity may characterize hyperalgesic states and some chronic pain conditions. Both animal and human imaging studies suggest that forebrain nociceptive systems are under inhibitory control by endogenous opioids; in humans, acute administration of -opioid receptor agonists blunts noxious heat-evoked activation in several brain areas. Anticipation of pain may in itself induce changes in brain nociceptive networks. Moreover, pain-related increases in cortical activity can be modulated by different cognitive processes, such as hypnotic suggestions, focussing or diverting attention, and placebo. These findings highlight the complexity of the pain system, and begin to disclose the spatio-temporal dynamics of brain networks underlying pain perception and modulation in health and disease
Cognitive modulation of pain and predictive coding. Comment on "Facing the experience of pain: a neuropsychological perspective" by Fabbro and Crescentini
No full textA commentary on the article “Facing the experience of pain: A neuropsychological perspective” by Fabbro and Crescentini, where the potential usefulness of adopting a predictive coding approach to understand pain perception is outlined
Spatial and temporal aspects of spinal cord and brainstem activation in the formalin pain model
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Functional magnetic resonance imaging as a tool for investigating human cortical motor function
No full textNon-invasive functional magnetic resonance imaging (fMRI) mapping techniques sensitive to the local changes of blood flow, blood volume, and blood oxygenation which accompany neuronal activation have been widely used over the last few years to investigate the functional organization of human cortical motor systems, and specifically of the primary motor cortex. Validation studies have demonstrated a good correspondence between quantitative and topographic aspects of data acquired by fMRI and positron emission tomography. The spatial and temporal resolution, affordable by fMRI has allowed to achieve new important information on the distributed representation of hand movements in multiple functional modules, and on the intensity and spatial extent of neural activation in the contralateral and ipsilateral primary motor cortex in relation to parametric and nonparametric aspects of movement and to the degree of handedness. Neural populations with different functional characteristics have been identified in anatomically defined regions, and the temporal aspects of the activation during voluntary movement tracked in different components of the motor system. Finally, this technique has proved useful to deepen our understanding of the neural basis of motor imagery, demonstrating increased activity in the primary motor cortex during mental representation of sequential finger movements
Pain Anticipation in the Cingulate Gyrus
No full textThroughout this chapter, we focus mainly on theinvolvement of the cingulate cortex in the anticipationof somatosensory input and specifi cally of pain. Thisissue has important theoretical and clinical implications,given the role of the cingulate cortex in themechanisms of pain and analgesia (see Chapters 14and 15). A specifi c question is that whether anticipationis able to affect the activity of pain-related populationsin the cingulate cortex and in the pain matrix in general.Indeed, it has long been hypothesized (James 1892)that essentially the same brain regions were implicatedboth in the anticipation and in the perception of astimulus; this hypothesis has now been directly testedby electrophysiological and functional imaging studiesin humans and non-human primates. Also, whenappropriate, we will briefl y compare the activity ofthe cingulate cortex during anticipation of painand during anticipation of other aversive or rewardevents. The specifi c goals of this chapter include thefollowing:1 Assess electrophysiological evidence of neurons activeduring pain anticipation in the cingulate cortex.2 Evaluate evidence from functional imaging studiesof activity changes related to somatosensory anticipationin different portions of the cingulate gyrus inhealthy volunteers and in pain patients.3 Appraise the modulation of basal- and stimulusevokedactivity of pain-related populations in thecingulate cortex and in other pain-related areas.4 Consider anticipation of pain and analgesia in termsof the potential underlying mechanisms and cingulatecircuits
Hypnotic susceptibility modulates brain activity related to experimental placebo analgesia
No full textIdentifying personality traits and neural signatures that predict placebo responsiveness is important, both on theoretical and practical grounds. In the present functional magnetic resonance imaging (fMRI) study, we performed multiple-regression interaction analysis to investigate whether hypnotic susceptibility (HS), a cognitive trait referring to the responsiveness to suggestions, explains interindividual differences in the neural mechanisms related to conditioned placebo analgesia in healthy volunteers. HS was not related to the overall strength of placebo analgesia. However, we found several HS-related differences in the patterns of fMRI activity and seed-based functional connectivity that accompanied placebo analgesia. Specifically, in subjects with higher HS, the placebo response was related to increased anticipatory activity in a right dorsolateral prefrontal cortex focus, and to reduced functional connectivity of that focus with brain regions related to emotional and evaluative pain processing (anterior mid-cingulate cortex/medial prefrontal cortex); an opposite pattern of fMRI activity and functional connectivity was found in subjects with lower HS. During pain perception, activity in the regions reflecting attention/arousal (bilateral anterior thalamus/left caudate) and self-related processing (left precuneus and bilateral posterior temporal foci) was negatively related to the strength of the analgesic placebo response in subjects with higher HS, but not in subjects with lower HS. These findings highlight HS influences on brain circuits related to the placebo analgesic effects. More generally, they demonstrate that different neural mechanisms can be involved in placebo responsiveness, depending on individual cognitive traits
Experimental designs and brain mapping approaches for studying the placebo analgesic effect
No full textThe placebo effect has intrigued scientists since it was proposed. The debate has now centered on how it works. Significant progress has been made and most of our knowledge about the neurobiological mechanisms comes from the field of pain and analgesia. The appropriateness of the experimental/clinical paradigms is crucial when we want to investigate the mechanisms of the placebo phenomenon. Recently, functional imaging techniques, such as positron emission tomography, magnetic resonance imaging, and electro/magnetoencephalography have also given the opportunity to define the neuroanatomical bases of placebo analgesia. This work systematically reviews the literature that deals with placebo analgesia, emphasizing both the methodological aspects and the neurobiological advances. The understanding of placebo mechanisms is fundamental and necessary to identify ways of accessing and harnessing these mechanisms in clinical practice to the patient’s benefit
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