Brain mediators of predictive cue effects on perceived pain

Functional imaging studies of emotion regulation: a synthetic review and evolving model of the cognitive control of emotion

This paper reviews and synthesizes functional imaging research that over the past decade has begun to offer new insights into the brain mechanisms underlying emotion regulation. Toward that end, the first section of the paper outlines a model of the processes and neural systems involved in emotion generation and regulation. The second section surveys recent research supporting and elaborating the model, focusing primarily on studies of the most commonly investigated strategy, which is known as reappraisal. At its core, the model specifies how prefrontal and cingulate control systems modulate activity in perceptual, semantic, and affect systems as a function of one's regulatory goals, tactics, and the nature of the stimuli and emotions being regulated. This section also shows how the model can be generalized to understand the brain mechanisms underlying other emotion regulation strategies as well as a range of other allied phenomena. The third and last section considers directions for future research, including how basic models of emotion regulation can be translated to understand changes in emotion across the life span and in clinical disorders.

A Social Neuroscience Perspective on Stress and Health

Psychological stress is a major risk factor for the development and progression of a number of diseases, including cardiovascular disease, cancer, arthritis, and major depression. A growing body of research suggests that long-term, stress-induced activation of the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis may lead to increases in inflammation, which is known to play a key role in the pathophysiology of a variety of diseases. Furthermore, the burgeoning fields of social neuroscience and health neuroscience have begun to identify the neurocognitive mechanisms by which stress may lead to these physiological changes. Here we review the literature examining the neurocognitive correlates of stress-induced SNS, HPA, and inflammatory responses. Specifically, we summarize the results of neuroimaging studies that have examined the neural correlates of stress-related increases in SNS, HPA, and inflammatory activity. A set of neural systems involved in threat processing, safety processing, and social cognition are suggested as key contributors to stress-related changes in physiology. We conclude by offering suggestions for future research in the exciting new field of health neuroscience.

tDCS Modulation of Visually Induced Analgesia

Multisensory interactions can produce analgesic effects. In particular, viewing one's own body reduces pain levels, perhaps because of changes in connectivity between visual areas specialized for body representation, and sensory areas underlying pain perception. We tested the causal role of the extrastriate visual cortex in triggering visually induced analgesia by modulating the excitability of this region with transcranial direct current stimulation (tDCS). Anodal, cathodal, or sham tDCS (2 mA, 10 min) was administered to 24 healthy participants over the right occipital or over the centro-parietal areas thought to be involved in the sensory processing of pain. Participants were required to rate the intensity of painful electrical stimuli while viewing either their left hand or an object occluding the left hand, both before and immediately after tDCS. We found that the analgesic effect of viewing the body was enhanced selectively by anodal stimulation of the occipital cortex. The effect was specific for the polarity and the site of stimulation. The present results indicate that visually induced analgesia may depend on neural signals from the extrastriate visual cortex.

Cortical and subcortical responses to high and low effective placebo treatments

The effectiveness of placebo treatments depends on the recipient's expectations, which are at least in part shaped by previous experiences. Thus, positive past experience together with an accordant verbal instruction should enhance outcome expectations and subsequently lead to higher placebo efficacy. This should be reflected in subjective valuation reports and in activation of placebo-related brain structures. We tested this hypothesis in a functional magnetic resonance imaging study, where subjects experienced different levels of pain relief and conforming information about price levels for two placebo treatments during a manipulation phase, thereby establishing a weak and a strong placebo. As expected, both placebos led to a significant pain relief and the strong placebo induced better analgesic efficacy. Individual placebo value estimates reflected treatment efficacy, i.e. subjects were willing to pay more money for the strong placebo even though pain stimulation was completed at this time. On the neural level, placebo effects were associated with activation of the rostral anterior cingulate cortex, the anterior insula, and the ventral striatum and deactivations in the thalamus and secondary somatosensory cortex. However, only placebo-related responses in rostral anterior cingulate cortex were consistent across both the anticipation of painful stimuli and their actual administration. Most importantly, rostral anterior cingulate cortex responses were higher for the strong placebo, thus mirroring the behavioral effects. These results directly link placebo analgesia to anticipatory activity in the ventral striatum, a region involved in reward processing, and highlight the role of the rostral anterior cingulate cortex, as its activity consistently scaled with increasing analgesic efficacy.

Low dose morphine adjuvant therapy for enhanced efficacy of antipsychotic drug action: potential involvement of endogenous morphine in the pathophysiology of schizophrenia

Major thematic threads linking extensive preclinical and clinical efforts have established a working mechanistic scheme whereby atypical antipsychotic drugs ameliorate negative DSM IV diagnostic criteria by effecting relatively potent blockade of serotonin (5-HT)(2A) receptors coupled with weaker antagonism of dopamine D(2) receptors in frontal cortical areas. These contentions are more or less supported by in vitro binding experiments employing cloned receptors on cultured cells, although significant functional involvement of 5-HT(2C) receptors has also been proposed. It is interesting that a key statistical analysis indicates a major shift in usage back to typical antipsychotic agents for management of schizophrenia from 1995–2008, whereas off-label usage of atypical antipsychotic agents was markedly increased or expanded for bipolar affective disorder. Importantly, meta-analyses generally did not support efficacy differences between the other atypical antipsychotics compared with the older typical agents. A critical examination of putative functional linkages of morphine and its type-selective mu opioid receptor to higher order cortical regulation of cognitive processes may provide novel insights into human behavioral processes that are severely impaired in schizophrenia spectrum disorders.

Altered anterior insula activation during anticipation and experience of painful stimuli in expert meditators

Experientially opening oneself to pain rather than avoiding it is said to reduce the mind's tendency toward avoidance or anxiety which can further exacerbate the experience of pain. This is a central feature of mindfulness-based therapies. Little is known about the neural mechanisms of mindfulness on pain. During a meditation practice similar to mindfulness, functional magnetic resonance imaging was used in expert meditators (>10,000 h of practice) to dissociate neural activation patterns associated with pain, its anticipation, and habituation. Compared to novices, expert meditators reported equal pain intensity, but less unpleasantness. This difference was associated with enhanced activity in the dorsal anterior insula (aI), and the anterior mid-cingulate (aMCC) the so-called 'salience network', for experts during pain. This enhanced activity during pain was associated with reduced baseline activity before pain in these regions and the amygdala for experts only. The reduced baseline activation in left aI correlated with lifetime meditation experience. This pattern of low baseline activity coupled with high response in aIns and aMCC was associated with enhanced neural habituation in amygdala and pain-related regions before painful stimulation and in the pain-related regions during painful stimulation. These findings suggest that cultivating experiential openness down-regulates anticipatory representation of aversive events, and increases the recruitment of attentional resources during pain, which is associated with faster neural habituation.

Neural similarity between encoding and retrieval is related to memory via hippocampal interactions

A fundamental principle in memory research is that memory is a function of the similarity between encoding and retrieval operations. Consistent with this principle, many neurobiological models of declarative memory assume that memory traces are stored in cortical regions, and the hippocampus facilitates the reactivation of these traces during retrieval. The present investigation tested the novel prediction that encoding-retrieval similarity can be observed and related to memory at the level of individual items. Multivariate representational similarity analysis was applied to functional magnetic resonance imaging data collected during encoding and retrieval of emotional and neutral scenes. Memory success tracked fluctuations in encoding-retrieval similarity across frontal and posterior cortices. Importantly, memory effects in posterior regions reflected increased similarity between item-specific representations during successful recognition. Mediation analyses revealed that the hippocampus mediated the link between cortical similarity and memory success, providing crucial evidence for hippocampal-cortical interactions during retrieval. Finally, because emotional arousal is known to modulate both perceptual and memory processes, similarity effects were compared for emotional and neutral scenes. Emotional arousal was associated with enhanced similarity between encoding and retrieval patterns. These findings speak to the promise of pattern similarity measures for evaluating memory representations and hippocampal-cortical interactions.

Dissociable influences of opiates and expectations on pain

Placebo treatments and opiate drugs are thought to have common effects on the opioid system and pain-related brain processes. This has created excitement about the potential for expectations to modulate drug effects themselves. If drug effects differ as a function of belief, this would challenge the assumptions underlying the standard clinical trial. We conducted two studies to directly examine the relationship between expectations and opioid analgesia. We administered the opioid agonist remifentanil to human subjects during experimental thermal pain and manipulated participants' knowledge of drug delivery using an open-hidden design. This allowed us to test drug effects, expectancy (knowledge) effects, and their interactions on pain reports and pain-related responses in the brain. Remifentanil and expectancy both reduced pain, but drug effects on pain reports and fMRI activity did not interact with expectancy. Regions associated with pain processing showed drug-induced modulation during both Open and Hidden conditions, with no differences in drug effects as a function of expectation. Instead, expectancy modulated activity in frontal cortex, with a separable time course from drug effects. These findings reveal that opiates and placebo treatments both influence clinically relevant outcomes and operate without mutual interference.

Effect of gentle cutaneous stimulation on heat-induced autonomic response and subjective pain intensity in healthy humans

The present study examined whether touch influences the autonomic responses and subjective pain intensity induced by noxious heat stimulation in humans. Heart rate and digital pulse wave were recorded. Heat stimulation was applied to the right plantar foot before, during, and after touch. Subjective pain intensity was evaluated using a visual analog scale (VAS). Touch was applied over the right medial malleolus for 10 min. Two types of touch were employed in a cross-over double-blinded randomized manner. When touch was applied with a soft elastomer brush, heat-induced autonomic responses attenuated significantly, while VAS scores were unchanged. In contrast, touch with a flat disc was ineffective for any measurement. Participants hardly perceived a difference in the texture of the touching materials. The present study result suggests there are mechanisms in conscious humans where some sort of touch inhibits nociceptive transmission into autonomic reflex pathways independent of sensation and cognition.

Opposing effects of expectancy and somatic focus on pain

High-pain expectancy increases pain and pain-related brain activity, creating a cycle of psychologically maintained pain. Though these effects are robust, little is known about how expectancy works and what psychological processes either support or mitigate its effects. To address this, we independently manipulated pain expectancy and “top-down” attention to the body, and examined their effects on both a performance-based measure of body-focus and heat-induced pain. Multi-level mediation analyses showed that high-pain expectancy substantially increased pain, replicating previous work. However, attention to the body reduced pain, partially suppressing the effects of expectancy. Furthermore, increased body-focus had larger pain-reducing effects when pain expectancy was high, suggesting that attempts to focus on external distractors are counterproductive in this situation. Overall, the results show that attention to the body cannot explain pain-enhancing expectancy effects, and that focusing on sensory/discriminative aspects of pain might be a useful pain-regulation strategy when severe pain is expected.

Common brain activations for painful and non-painful aversive stimuli

BACKGROUND

Identification of potentially harmful stimuli is necessary for the well-being and self-preservation of all organisms. However, the neural substrates involved in the processing of aversive stimuli are not well understood. For instance, painful and non-painful aversive stimuli are largely thought to activate different neural networks. However, it is presently unclear whether there is a common aversion-related network of brain regions responsible for the basic processing of aversive stimuli. To help clarify this issue, this report used a cross-species translational approach in humans (i.e. meta-analysis) and rodents (i.e. systematic review of functional neuroanatomy).

RESULTS

Animal and human data combined to show a core aversion-related network, consisting of similar cortical (i.e. MCC, PCC, AI, DMPFC, RTG, SMA, VLOFC; see results section or abbreviation section for full names) and subcortical (i.e. Amyg, BNST, DS, Hab, Hipp/Parahipp, Hyp, NAc, NTS, PAG, PBN, raphe, septal nuclei, Thal, LC, midbrain) regions. In addition, a number of regions appeared to be more involved in pain-related (e.g. sensory cortex) or non-pain-related (e.g. amygdala) aversive processing.

CONCLUSIONS

This investigation suggests that aversive processing, at the most basic level, relies on similar neural substrates, and that differential responses may be due, in part, to the recruitment of additional structures as well as the spatio-temporal dynamic activity of the network. This network perspective may provide a clearer understanding of why components of this circuit appear dysfunctional in some psychiatric and pain-related disorders.

The brain's default network and its adaptive role in internal mentation

During the many idle moments that comprise daily life, the human brain increases its activity across a set of midline and lateral cortical brain regions known as the "default network." Despite the robustness with which the brain defaults to this pattern of activity, surprisingly little is known about the network's precise anatomical organization and adaptive functions. To provide insight into these questions, this article synthesizes recent literature from structural and functional imaging with a growing behavioral literature on mind wandering. Results characterize the default network as a set of interacting hubs and subsystems that play an important role in "internal mentation"-the introspective and adaptive mental activities in which humans spontaneously and deliberately engage in every day.

Sensorimotor resonance is an outcome but not a platform to anticipating harm to others

When perceiving imminent harm to others, quickly detecting potential hazards to oneself should be vital. In this case, mirroring the outcome of observed actions appears paradoxical. This study measured electroencephalographic/event-related potentials and mu suppression that were induced by dynamic animations; each animation was composed of three consecutive pictures depicting an individual being accidentally injured. The results indicated that the first picture evoked frontal N260 and central N360, the possible brain source of which is estimated in the dorsolateral prefrontal cortex, and the third picture elicited late positive potentials, the possible sources of which might be generated from the insular and mid-cingulate cortex. Differential mu suppression, in relation to the sensorimotor resonance of empathy for pain, is associated with the third picture containing the crucial affective valence, but not with the first picture. The masking procedure on the third picture attenuated this mu suppression. Mediation analysis further confirmed that sensorimotor resonance is not a significant mediator in predicting subjective unpleasantness for observed actions. The findings suggest that sensorimotor resonance is not a platform, but rather an outcome when anticipating harm to others.

Mindfulness meditation-related pain relief: evidence for unique brain mechanisms in the regulation of pain

The cognitive modulation of pain is influenced by a number of factors ranging from attention, beliefs, conditioning, expectations, mood, and the regulation of emotional responses to noxious sensory events. Recently, mindfulness meditation has been found attenuate pain through some of these mechanisms including enhanced cognitive and emotional control, as well as altering the contextual evaluation of sensory events. This review discusses the brain mechanisms involved in mindfulness meditation-related pain relief across different meditative techniques, expertise and training levels, experimental procedures, and neuroimaging methodologies. Converging lines of neuroimaging evidence reveal that mindfulness meditation-related pain relief is associated with unique appraisal cognitive processes depending on expertise level and meditation tradition. Moreover, it is postulated that mindfulness meditation-related pain relief may share a common final pathway with other cognitive techniques in the modulation of pain.

Dynamic connectivity regression: determining state-related changes in brain connectivity

Most statistical analyses of fMRI data assume that the nature, timing and duration of the psychological processes being studied are known. However, often it is hard to specify this information a priori. In this work we introduce a data-driven technique for partitioning the experimental time course into distinct temporal intervals with different multivariate functional connectivity patterns between a set of regions of interest (ROIs). The technique, called Dynamic Connectivity Regression (DCR), detects temporal change points in functional connectivity and estimates a graph, or set of relationships between ROIs, for data in the temporal partition that falls between pairs of change points. Hence, DCR allows for estimation of both the time of change in connectivity and the connectivity graph for each partition, without requiring prior knowledge of the nature of the experimental design. Permutation and bootstrapping methods are used to perform inference on the change points. The method is applied to various simulated data sets as well as to an fMRI data set from a study (N=26) of a state anxiety induction using a socially evaluative threat challenge. The results illustrate the method's ability to observe how the networks between different brain regions changed with subjects' emotional state.

Common representation of pain and negative emotion in the midbrain periaqueductal gray

Human neuroimaging offers a powerful way to connect animal and human research on emotion, with profound implications for psychological science. However, the gulf between animal and human studies remains a formidable obstacle: human studies typically focus on the cortex and a few subcortical regions such as the amygdala, whereas deeper structures such as the brainstem periaqueductal gray (PAG) play a key role in animal models. Here, we directly assessed the role of PAG in human affect by interleaving in a single fMRI session two conditions known to elicit strong emotional responses--physical pain and negative image viewing. Negative affect and PAG activity increased in both conditions. We next examined eight independent data sets, half featuring pain stimulation and half negative image viewing. In sum, these data sets comprised 198 additional participants. We found increased activity in PAG in all eight studies. Taken together, these findings suggest PAG is a key component of human affective responses.

Serotonin transporter polyadenylation polymorphism modulates the retention of fear extinction memory

Growing evidence suggests serotonin's role in anxiety and depression is mediated by its effects on learned fear associations. Pharmacological and genetic manipulations of serotonin signaling in mice alter the retention of fear extinction learning, which is inversely associated with anxious temperament in mice and humans. Here, we test whether genetic variation in serotonin signaling in the form of a common human serotonin transporter polyadenylation polymorphism (STPP/rs3813034) is associated with spontaneous fear recovery after extinction. We show that the risk allele of this polymorphism is associated with impaired retention of fear extinction memory and heightened anxiety and depressive symptoms. These STPP associations in humans mirror the phenotypic effects of serotonin transporter knockout in mice, highlighting the STPP as a potential genetic locus underlying interindividual differences in serotonin transporter function in humans. Furthermore, we show that the serotonin transporter polyadenylation profile associated with the STPP risk allele is altered through the chronic administration of fluoxetine, a treatment that also facilitates retention of extinction learning. The propensity to form persistent fear associations due to poor extinction recall may be an intermediate phenotype mediating the effects of genetic variation in serotonergic function on anxiety and depression. The consistency and specificity of these data across species provide robust support for this hypothesis and suggest that the little-studied STPP may be an important risk factor for mood and anxiety disorders in humans.

Brain responses to visceral stimuli reflect visceral sensitivity thresholds in patients with irritable bowel syndrome

BACKGROUND & AIMS

Only a fraction of patients with irritable bowel syndrome (IBS) have increased perceptual sensitivity to rectal distension, indicating differences in processing and/or modulation of visceral afferent signals. We investigated the brain mechanisms of these perceptual differences.

METHODS

We analyzed data from 44 women with IBS and 20 female healthy subjects (controls). IBS symptom severity was determined by a severity scoring system. Anxiety and depression symptoms were assessed using the hospital anxiety and depression score. Blood oxygen level-dependent signals were measured by functional magnetic resonance imaging during expectation and delivery of high (45 mmHg) and low (15 mmHg) intensity rectal distensions. Perception thresholds to rectal distension were determined in the scanner. Brain imaging data were compared among 18 normosensitive and 15 hypersensitive patients with IBS and 18 controls. Results were reported significant if peak P-values were ≤.05, with family-wise error correction in regions of interest.

RESULTS

The subgroups of patients with IBS were similar in age, symptom duration, psychological symptoms, and IBS symptom severity. Although brain responses to distension were similar between normosensitive patients and controls, hypersensitive patients with IBS had greater activation of insula and reduced deactivation in pregenual anterior cingulate cortex during noxious rectal distensions, compared to controls and normosensitive patients with IBS. During expectation of rectal distension, normosensitive patients with IBS had more activation in right hippocampus than controls.

CONCLUSIONS

Despite similarities in symptoms, hyper- and normosensitive patients with IBS differ in cerebral responses to standardized rectal distensions and their expectation, consistent with differences in ascending visceral afferent input.

Ventromedial prefrontal-subcortical systems and the generation of affective meaning

The ventromedial prefrontal cortex (vmPFC) comprises a set of interconnected regions that integrate information from affective sensory and social cues, long-term memory, and representations of the 'self'. Alhough the vmPFC is implicated in a variety of seemingly disparate processes, these processes are organized around a common theme. The vmPFC is not necessary for affective responses per se, but is critical when affective responses are shaped by conceptual information about specific outcomes. The vmPFC thus functions as a hub that links concepts with brainstem systems capable of coordinating organism-wide emotional behavior, a process we describe in terms of the generation of affective meaning, and which could explain the common role played by the vmPFC in a range of experimental paradigms.

Felt and seen pain evoke the same local patterns of cortical activity in insular and cingulate cortex

The discovery of regions in the human brain (e.g., insula and cingulate cortex) that activate both under direct exposure to pain and when perceiving pain in others has been interpreted as a neural signature of empathy. However, this overlap raises the question of whether it may reflect a unique distributed population of bimodal neurons or, alternatively, the activity of intermingled but independent populations. We used fMRI on 28 female volunteers and used multivariate pattern analysis techniques to probe for more fine-grain spatial representations of seen and felt pain. Using a whole-brain approach, we found that only in the anterior insula (bilaterally) the distribution of cortical activity evoked by seeing another person's hand in pain was spatially similar to that of pain felt on one's own hand. Subsequent region of interest analyses also implicated the middle insula (right hemisphere) and the middle cingulate cortex. Furthermore, for the anterior insula, the spatial distribution of activity associated with one's pain also replicates that of the perception of negative but painless stimuli. Our data show how the neural representations of aversive events affecting oneself are also recruited when the same events affect others, and provide the stronger evidence thus far of a unique distributed cortical ensemble coding for aversive events regardless of the subject who is affected.

Distraction and placebo: two separate routes to pain control

An explosion of recent research has studied whether placebo treatments influence health-related outcomes and their biological markers, but almost no research has examined the psychological processes required for placebo effects to occur. This study tested whether placebo treatment and cognitive distraction reduce pain through shared or independent processes. We tested the joint effects of performance of an executive working memory task and placebo treatment on thermal pain perception. An interactive effect of these two manipulations would constitute evidence for shared mechanisms, whereas additive effects would imply separate mechanisms. Participants (N = 33) reported reduced pain both when they performed the working memory task and when they received the placebo treatment, but the reductions were additive, a result indicating that the executive demands of the working memory task did not interfere with placebo analgesia. Furthermore, placebo analgesia did not impair task performance. Together, these data suggest that placebo analgesia does not depend on active redirection of attention and that expectancy and distraction can be combined to maximize pain relief.

The placebo effect: advances from different methodological approaches

There is accumulating evidence from different methodological approaches that the placebo effect is a neurobiological phenomenon. Behavioral, psychophysiological, and neuroimaging results have largely contributed to accepting the placebo response as real. A major aspect of recent and future advances in placebo research is to demonstrate linkages between behavior, brain, and bodily responses. This article provides an overview of the processes involved in the formation of placebo responses by combining research findings from behavioral, psychophysiological, and neuroimaging methods. The integration of these different methodological approaches is a key objective, motivating our scientific pursuits toward a placebo research that can inform and guide important future scientific knowledge.

Distinct roles of the 'shared pain' and 'theory of mind' networks in processing others' emotional suffering

The brain mechanisms involved in processing another's physical pain have been extensively studied in recent years. The link between understanding others' physical pain and emotional suffering is less well understood. Using whole brain analysis and two separate functional localizers, we characterized the neural response profiles of narrative scenarios involving physical pain (PP), and scenarios involving emotional pain (EP) with functional magnetic resonance imaging (fMRI). Whole brain analyses revealed that PP narratives activated the Shared Pain network, and that the brain regions responsible for processing EP overlapped substantially with brain regions involved in Theory of Mind. Region of interest (ROI) analysis provided a finer-grained view. Some regions responded to stories involving physical states, regardless of painful content (secondary sensory regions), some selectively responded to both emotionally and physically painful events (bilateral anterior thalamus and anterior middle cingulate cortex), one brain region responded selectively to physical pain (left insula), and one brain region responded selectively to emotional pain (dorsomedial prefrontal cortex). These results replicated in two groups of participants given different explicit tasks. Together, these results clarify the distinct roles of multiple brain regions in responding to others who are in physical or emotional pain.

Neural mechanisms mediating the effects of expectation in visceral placebo analgesia: an fMRI study in healthy placebo responders and nonresponders

This functional magnetic resonance imaging study analysed the behavioural and neural responses during expectation-mediated placebo analgesia in a rectal pain model in healthy subjects. In N=36 healthy subjects, the blood oxygen level-dependent (BOLD) response during cued anticipation and painful rectal stimulation was measured. Using a within-subject design, placebo analgesia was induced by changing expectations regarding the probability of receiving an analgesic drug to 0%, 50%, and 100%. Placebo responders were identified by median split based on pain reduction (0% to 100% conditions), and changes in neural activation correlating with pain reduction in the 0% and 100% conditions were assessed in a regions-of-interest analysis. Expectation of pain relief resulted in overall reductions in pain and urge to defecate, and this response was significantly more pronounced in responders. Within responders, pain reduction correlated with reduced activation of dorsolateral and ventrolateral prefrontal cortices, somatosensory cortex, and thalamus during cued anticipation (paired t tests on the contrast 0%>100%); during painful stimulation, pain reduction correlated with reduced activation of the thalamus. Compared with nonresponders, responders demonstrated greater placebo-induced decreases in activation of dorsolateral prefrontal cortex during anticipation and in somatosensory cortex, posterior cingulate cortex, and thalamus during pain. In conclusion, the expectation of pain relief can substantially change perceived painfulness of visceral stimuli, which is associated with activity changes in the thalamus, prefrontal, and somatosensory cortices. Placebo analgesia constitutes a paradigm to elucidate psychological components of the pain response relevant to the pathophysiology and treatment of chronic abdominal pain.

Attachment figures activate a safety signal-related neural region and reduce pain experience

Although it has long been hypothesized that attachment figures provide individuals with a sense of safety and security, the neural mechanisms underlying attachment-induced safety have not been explored. Here, we investigated whether an attachment figure acts as a safety signal by exploring whether viewing an attachment figure during a threatening experience (physical pain) led to increased activity in a neural region associated with safety signaling, the ventromedial prefrontal cortex (VMPFC), and corresponding reductions in pain. Female participants in long-term romantic relationships were scanned as they received painful stimuli while viewing pictures of their partner and control images (stranger, object). Consistent with the idea that the attachment figure may signal safety, results revealed that viewing partner pictures while receiving painful stimulation led to reductions in self-reported pain ratings, reductions in pain-related neural activity (dorsal anterior cingulate cortex, anterior insula), and increased activity in the VMPFC. Moreover, greater VMPFC activity in response to partner pictures was associated with longer relationship lengths and greater perceived partner support, further highlighting a role for the VMPFC in responding to the safety value of the partner. Last, greater VMPFC activity while viewing partner pictures was associated with reduced pain ratings and reduced pain-related neural activity. An implication of these findings is that, in the same way that stimuli that historically have threatened survival (e.g., snakes, spiders) are considered to be prepared fear stimuli, attachment figures, who have historically benefited survival, may serve as prepared safety stimuli, reducing threat- or distress-related responding in their presence.

Large-scale automated synthesis of human functional neuroimaging data

The rapid growth of the literature on neuroimaging in humans has led to major advances in our understanding of human brain function but has also made it increasingly difficult to aggregate and synthesize neuroimaging findings. Here we describe and validate an automated brain-mapping framework that uses text-mining, meta-analysis and machine-learning techniques to generate a large database of mappings between neural and cognitive states. We show that our approach can be used to automatically conduct large-scale, high-quality neuroimaging meta-analyses, address long-standing inferential problems in the neuroimaging literature and support accurate 'decoding' of broad cognitive states from brain activity in both entire studies and individual human subjects. Collectively, our results have validated a powerful and generative framework for synthesizing human neuroimaging data on an unprecedented scale.

Large-scale automated synthesis of human functional neuroimaging data

The explosive growth of the human neuroimaging literature has led to major advances in understanding of human brain function, but has also made aggregation and synthesis of neuroimaging findings increasingly difficult. Here we describe and validate an automated brain mapping framework that uses text mining, meta-analysis and machine learning techniques to generate a large database of mappings between neural and cognitive states. We demonstrate the capacity of our approach to automatically conduct large-scale, high-quality neuroimaging meta-analyses, address long-standing inferential problems in the neuroimaging literature, and support accurate ‘decoding’ of broad cognitive states from brain activity in both entire studies and individual human subjects. Collectively, our results validate a powerful and generative framework for synthesizing human neuroimaging data on an unprecedented scale.

The integration of negative affect, pain and cognitive control in the cingulate cortex

It has been argued that emotion, pain and cognitive control are functionally segregated in distinct subdivisions of the cingulate cortex. However, recent observations encourage a fundamentally different view. Imaging studies demonstrate that negative affect, pain and cognitive control activate an overlapping region of the dorsal cingulate--the anterior midcingulate cortex (aMCC). Anatomical studies reveal that the aMCC constitutes a hub where information about reinforcers can be linked to motor centres responsible for expressing affect and executing goal-directed behaviour. Computational modelling and other kinds of evidence suggest that this intimacy reflects control processes that are common to all three domains. These observations compel a reconsideration of the dorsal cingulate's contribution to negative affect and pain.

Relief as a reward: hedonic and neural responses to safety from pain

Relief fits the definition of a reward. Unlike other reward types the pleasantness of relief depends on the violation of a negative expectation, yet this has not been investigated using neuroimaging approaches. We hypothesized that the degree of negative expectation depends on state (dread) and trait (pessimism) sensitivity. Of the brain regions that are involved in mediating pleasure, the nucleus accumbens also signals unexpected reward and positive prediction error. We hypothesized that accumbens activity reflects the level of negative expectation and subsequent pleasant relief. Using fMRI and two purpose-made tasks, we compared hedonic and BOLD responses to relief with responses during an appetitive reward task in 18 healthy volunteers. We expected some similarities in task responses, reflecting common neural substrates implicated across reward types. However, we also hypothesized that relief responses would differ from appetitive rewards in the nucleus accumbens, since only relief pleasantness depends on negative expectations. The results confirmed these hypotheses. Relief and appetitive reward task activity converged in the ventromedial prefrontal cortex, which also correlated with appetitive reward pleasantness ratings. In contrast, dread and pessimism scores correlated with relief but not with appetitive reward hedonics. Moreover, only relief pleasantness covaried with accumbens activation. Importantly, the accumbens signal appeared to specifically reflect individual differences in anticipation of the adverse event (dread, pessimism) but was uncorrelated to appetitive reward hedonics. In conclusion, relief differs from appetitive rewards due to its reliance on negative expectations, the violation of which is reflected in relief-related accumbens activation.

Uncertainty is associated with biased expectancies and heightened responses to aversion

Uncertainty is an omnipresent force in peoples' lives that has been shown to amplify the negative impact of aversive events. This amplified aversiveness, together with the negative attitudes that individuals can have toward uncertainty, suggests that a cue indicating uncertainty about future events might be associated with biased expectancies of negative outcomes or biased contingency estimates, similar to biases that have been observed for traditional fear-relevant cues, such as snakes or spiders. Participants in this study saw three different cues: one that indicated with certainty that an aversive picture would follow, one that indicated with certainty that a neutral picture would follow, and one that indicated uncertainty about whether an aversive or neutral picture would follow. Online self-report data revealed negatively biased expectancies of aversion after uncertain cues. The degree of this online expectancy bias predicted participants' estimates, at the conclusion of the experiment, of the relationship between uncertain cues and aversive pictures. Aversive pictures after the uncertain cue (relative to those after the certain cue) were accompanied by increased skin conductance responses and self-reported negative mood. These findings that uncertainty is accompanied by biased expectancies of aversion and heightened responses to aversion warrant extensions of this research in anxiety disorders, given evidence for intolerance of uncertainty and anticipatory dysfunction in the pathology of such disorders.

Reward reduces conflict by enhancing attentional control and biasing visual cortical processing

How does motivation interact with cognitive control during challenging behavioral conditions? Here, we investigated the interactions between motivation and cognition during a response conflict task and tested a specific model of the effect of reward on cognitive processing. Behaviorally, participants exhibited reduced conflict during the reward versus no-reward condition. Brain imaging results revealed that a group of subcortical and fronto-parietal regions was robustly influenced by reward at cue processing and, importantly, that cue-related responses in fronto-parietal attentional regions were predictive of reduced conflict-related signals in the medial pFC (MPFC)/ACC during the upcoming target phase. Path analysis revealed that the relationship between cue responses in the right intraparietal sulcus (IPS) and interference-related responses in the MPFC during the subsequent target phase was mediated via signals in the left fusiform gyrus, which we linked to distractor-related processing. Finally, reward increased functional connectivity between the right IPS and both bilateral putamen and bilateral nucleus accumbens during the cue phase, a relationship that covaried with across-individual sensitivity to reward in the case of the right nucleus accumbens. Taken together, our findings are consistent with a model in which motivationally salient cues are employed to upregulate top-down control processes that bias the selection of visual information, thereby leading to more efficient stimulus processing during conflict conditions.

Predicting individual differences in placebo analgesia: contributions of brain activity during anticipation and pain experience

Recent studies have identified brain correlates of placebo analgesia, but none have assessed how accurately patterns of brain activity can predict individual differences in placebo responses. We reanalyzed data from two fMRI studies of placebo analgesia (N = 47), using patterns of fMRI activity during the anticipation and experience of pain to predict new subjects' scores on placebo analgesia and placebo-induced changes in pain processing. We used a cross-validated regression procedure, LASSO-PCR, which provided both unbiased estimates of predictive accuracy and interpretable maps of which regions are most important for prediction. Increased anticipatory activity in a frontoparietal network and decreases in a posterior insular/temporal network predicted placebo analgesia. Patterns of anticipatory activity across the cortex predicted a moderate amount of variance in the placebo response (∼12% overall, ∼40% for study 2 alone), which is substantial considering the multiple likely contributing factors. The most predictive regions were those associated with emotional appraisal, rather than cognitive control or pain processing. During pain, decreases in limbic and paralimbic regions most strongly predicted placebo analgesia. Responses within canonical pain-processing regions explained significant variance in placebo analgesia, but the pattern of effects was inconsistent with widespread decreases in nociceptive processing. Together, the findings suggest that engagement of emotional appraisal circuits drives individual variation in placebo analgesia, rather than early suppression of nociceptive processing. This approach provides a framework that will allow prediction accuracy to increase as new studies provide more precise information for future predictive models.