Different brain networks mediate the effects of social and conditioned expectations on pain.

Information about others' experiences can strongly influence our own feelings and decisions. But how does such social information affect the neural generation of affective experience, and are the brain mechanisms involved distinct from those that mediate other types of expectation effects? Here, we used fMRI to dissociate the brain mediators of social influence and associative learning effects on pain. Participants viewed symbolic depictions of other participants' pain ratings (social information) and classically conditioned pain-predictive cues before experiencing painful heat. Social information and conditioned stimuli each had significant effects on pain ratings, and both effects were mediated by self-reported expectations. Yet, these effects were mediated by largely separable brain activity patterns, involving different large-scale functional networks. These results show that learned versus socially instructed expectations modulate pain via partially different mechanisms-a distinction that should be accounted for by theories of predictive coding and related top-down influences

Neural response to the observable self in social anxiety disorder

Background: Distorted images of the observable self are considered crucial in the development and maintenance of social anxiety. We generated an experimental situation in which participants viewed themselves from an observer's perspective when exposed to scrutiny and evaluation by others. Method: Twenty patients with social anxiety disorder (SAD) and 20 control subjects were assessed using functional magnetic resonance imaging (fMRI) during the public exposure of pre-recorded videos in which they were each shown performing a verbal task. The examiners acted as the audience in the experiment and rated performance. Whole-brain functional maps were computed using Statistical Parametric Mapping. Results: Robust activation was observed in regions related to self-face recognition, emotional response and general arousal in both study groups. Patients showed significantly greater activation only in the primary visual cortex. By contrast, they showed significant deactivation or smaller activation in dorsal frontoparietal and anterior cingulate cortices relevant to the cognitive control of negative emotion. Task-related anxiety ratings revealed a pattern of negative correlation with activation in this frontoparietal/cingulate network. Importantly, the relationship between social anxiety scores and neural response showed an inverted-U function with positive correlations in the lower score range and negative correlations in the higher range. Conclusions: Our findings suggest that exposure to scrutiny and evaluation in SAD may be associated with changes in cortical systems mediating the cognitive components of anxiety. Disorder severity seems to be relevant in shaping the neural response pattern, which is distinctively characterized by a reduced cortical response in the most severe cases

Altered corticostriatal functional connectivity in obsessive-compulsive disorder

Context: neurobiological models of obsessive-compulsive disorder (OCD) emphasize disturbances in the function and connectivity of brain corticostriatal networks, or 'loops.' Although neuroimaging studies of patients have supported this network model of OCD, very few have applied measurements that are sensitive to brain connectivity features. Objective: using resting-state functional magnetic resonance imaging, we tested the hypothesis that OCD is associated with disturbances in the functional connectivity of primarily ventral corticostriatal regions, measured from coherent spontaneous fluctuations in the blood oxygenation level-dependent (BOLD) signal. Design: case-control cross-sectional study. Setting: hospital referral OCD unit and magnetic resonance imaging facility. Participants: a total of 21 patients with OCD (10 men, 11 women) and 21 healthy control subjects matched for age, sex, and estimated intelligence. Main outcome measures: voxelwise statistical parametric maps testing the strength of functional connectivity of 4 striatal seed regions of interest (dorsal caudate nucleus, ventral caudate/nucleus accumbens, dorsal putamen, and ventral putamen) with remaining brain areas. Results: for both groups, there was a clear distinction in the pattern of cortical connectivity of dorsal and ventral striatal regions, consistent with the notion of segregated motor, associative, and limbic corticostriatal networks. Between groups, patients with OCD had significantly increased functional connectivity along a ventral corticostriatal axis, implicating the orbitofrontal cortex and surrounding areas. The specific strength of connectivity between the ventral caudate/nucleus accumbens and the anterior orbitofrontal cortex predicted patients' overall symptom severity (r(2) = 0.57; P < .001). Additionally, patients with OCD showed evidence of reduced functional connectivity of the dorsal striatum and lateral prefrontal cortex, and of the ventral striatum with the region of the midbrain ventral tegmental area. Conclusions: this study directly supports the hypothesis that OCD is associated with functional alterations of brain corticostriatal networks. Specifically, our findings emphasize abnormal and heightened functional connectivity of ventrolimbic corticostriatal regions in patients with OCD

Task-induced deactivation from rest extends beyond the default mode brain network

Activity decreases, or deactivations, of midline and parietal cortical brain regions are routinely observed in human functional neuroimaging studies that compare periods of task-based cognitive performance with passive states, such as rest. It is now widely held that such task-induced deactivations index a highly organized"default-mode network" (DMN): a large-scale brain system whose discovery has had broad implications in the study of human brain function and behavior. In this work, we show that common task-induced deactivations from rest also occur outside of the DMN as a function of increased task demand. Fifty healthy adult subjects performed two distinct functional magnetic resonance imaging tasks that were designed to reliably map deactivations from a resting baseline. As primary findings, increases in task demand consistently modulated the regional anatomy of DMN deactivation. At high levels of task demand, robust deactivation was observed in non-DMN regions, most notably, the posterior insular cortex. Deactivation of this region was directly implicated in a performance-based analysis of experienced task difficulty. Together, these findings suggest that task-induced deactivations from rest are not limited to the DMN and extend to brain regions typically associated with integrative sensory and interoceptive processes

Neural correlates of moral sensitivity in obsessive-compulsive disorder

Context: heightened moral sensitivity seems to characterize patients with obsessive-compulsive disorder (OCD). Recent advances in social cognitive neuroscience suggest that a compelling relationship may exist between this disorder-relevant processing bias and the functional activity of brain regions implicated in OCD. Objective: to test the hypothesis that patients with OCD demonstrate an increased response of relevant ventromedial prefrontal and orbitofrontal cortex regions in a functional magnetic resonance imaging study of difficult moral decision making. Design: case-control cross-sectional study. Setting: hospital referral OCD unit and magnetic resonance imaging facility. Participants: seventy-three patients with OCD (42 men and 31 women) and 73 control participants matched for age, sex, and education level. Main outcome measures: functional magnetic resonance imaging activation maps representing significant changes in blood oxygenation level-dependent signal in response to 24 hypothetical moral dilemma vs nondilemma task vignettes and additional activation maps representing significant linear associations between patients' brain responses and symptom severity ratings. Results: in both groups, moral dilemma led to robust activation of frontal and temporoparietal brain regions. Supporting predictions, patients with OCD demonstrated significantly increased activation of the ventral frontal cortex, particularly of the medial orbitofrontal cortex. In addition, the left dorsolateral prefrontal cortex and left middle temporal gyrus were more robustly activated in patients with OCD. These results were unexplained by group differences in comorbid affective symptoms. Patients' global illness severity predicted the relative magnitude of orbitofrontal-striatal activation. The severity of 'harm/checking' symptoms and 'sexual/religious' obsessions predicted the magnitude of posterior temporal and amygdala-paralimbic activation, respectively. Conclusions: the neural correlates of moral sensitivity in patients with OCD partly coincide with brain regions that are of general interest to pathophysiologic models of this disorder. In particular, these findings suggest that the orbitofrontal cortex together with the left dorsolateral prefrontal cortex may be relevant for understanding the link between neurobiological processes and certain maladaptive cognitions in OCD

The dynamic dimension of the emotional experience assessed during painful stimulation and in the resting-state using functional magnetic resonance imaging

[eng] The PhD thesis aimed to characterize the dynamic or temporal dimension of the emotional experience assessed using functional magnetic resonance imaging (fMRI). Brain response to primary emotional stimuli and basal brain functional connectivity during a sustained resting-state have been analyzed using a dynamic approach in healthy subjects and in patients suffering from fibromyalgia and major depression (MDD), both disorders showing relevant abnormalities in the affective sphere. The technical advance recently incorporated to the field of fMRI data acquisition and analysis has made possible the dynamic study of the human emotional experience from a brain-system perspective. Two different approaches were employed. The first approach (i) was intended to dynamically characterize brain responses in emotion circuits when specifically targeted by aversive painful stimulation, considered a primary elicitor of emotional responses, in healthy subjects and in the selected clinical populations. The second approach (ii) specifically aimed to dynamically characterize the "baseline" functional organization of distinct emotion-processing circuits in healthy subjects and in a core affective disorder such as major depression. Four studies compose the PhD thesis. The first study assessed the existence of regional specialization within the right lateral aspect of the frontal cortex, important for the affective modulation of pain perception, on the basis of their response dynamics during mechanical painful stimulation in a group of healthy subjects. Three distinct locations were found with separate temporal courses of activation showing each of them a different contribution to the final experience of pain reported by the subject. In the second study, information concerning the actual brain response dynamics (time-courses of brain responses) to painful stimulation were used in a group of fibromyalgia patients (and in healthy subjects) to better characterize their overall subjective pain experience and the specific contribution of brain emotional processing abnormalities to such a clinical disorder. The dynamic analysis approach successfully identified relevant abnormalities in the patients' response to pain that would have not been possibly detected with a conventional model-based approach based on the fixed stimulus duration. The third study aimed to assess possible alterations in the baseline functional organization of the emotion-related brain networks during resting-state (stimulation free) conditions in a group of MDD patients, characterized by a continuous and severe negative affective state. Gray-matter abnormalities observed in MDD patients guided the functional connectivity study, which successfully captured major brain networks relevant to MDD physiopathology. Overall, the baseline functional disposition of the brain systems under study revealed functional connectivity disruptions (loss of coherence between fMRI signal fluctuations in distinct brain regions) affecting most of the networks, coinciding with the general hypo-functional state characterizing such patients. Specific functional connectivity enhancements were also found in regions integrating the basic threat response circuit, which may be associated with the sustained stress characterizing MDD patients. Finally, the fourth study aimed to characterize the temporal changes in the abnormal responses to aversive painful stimulation in MDD patients following one and eight weeks of antidepressant treatment observed within relevant emotion brain circuits, and the specific brain correlates of affect-related symptomatic improvement in such patients. The dynamic study successfully identified (i) the normalization of brain hyper-responses to painful stimulation in emotion-related systems in MDD patients, associated with their symptomatic improvement following antidepressant treatment (ii) brain imaging correlates of symptomatic improvement in specific clinical dimensions of interest (iii) baseline brain response measurements predicting clinical responders following 8 weeks of antidepressant treatment. All in all, the four studies presented in the PhD thesis constitute a step forward in the dynamic characterization of how the brain constructs emotion perception and sustained affective states in the context of both health and disease

Functional Connectivity Bias in the Prefrontal Cortex of Psychopaths

Background: Psychopathy is characterized by a distinctive interpersonal style that combines callous-unemotional traits with inflexible and antisocial behavior. Traditional emotion-based perspectives link emotional impairment mostly to alterations in amygdala-ventromedial frontal circuits. However, these models alone cannot explain why individuals with psychopathy can regularly benefit from emotional information when placed on their focus of attention and why they are more resistant to interference from nonaffective contextual cues. The present study aimed to identify abnormal or distinctive functional links between and within emotional and cognitive brain systems in the psychopathic brain to characterize further the neural bases of psychopathy. Methods: High-resolution anatomic magnetic resonance imaging with a functional sequence acquired in the resting state was used to assess 22 subjects with psychopathy and 22 control subjects. Anatomic and functional connectivity alterations were investigated first using a whole-brain analysis. Brain regions showing overlapping anatomic and functional changes were examined further using seed-based functional connectivity mapping. Results: Subjects with psychopathy showed gray matter reduction involving prefrontal cortex, paralimbic, and limbic structures. Anatomic changes overlapped with areas showing increased degree of functional connectivity at the medial-dorsal frontal cortex. Subsequent functional seed-based connectivity mapping revealed a pattern of reduced functional connectivity of prefrontal areas with limbic-paralimbic structures and enhanced connectivity within the dorsal frontal lobe in subjects with psychopathy. Conclusions: Our results suggest that a weakened link between emotional and cognitive domains in the psychopathic brain may combine with enhanced functional connections within frontal executive areas. The identified functional alterations are discussed in the context of potential contributors to the inflexible behavior displayed by individuals with psychopathy

Cerebrospinal fluid space alterations in melancholic depression

Melancholic depression is a biologically homogeneous clinical entity in which structural brain alterations have been described. Interestingly, reports of structural alterations in melancholia include volume increases in Cerebro-Spinal Fluid (CSF) spaces. However, there are no previous reports of CSF volume alterations using automated whole-brain voxel-wise approaches, as tissue classification algorithms have been traditionally regarded as less reliable for CSF segmentation. Here we aimed to assess CSF volumetric alterations in melancholic depression and their clinical correlates by means of a novel segmentation algorithm ('new segment', as implemented in the software Statistical Parametric Mapping-SPM8), incorporating specific features that may improve CSF segmentation. A three-dimensional Magnetic Resonance Image (MRI) was obtained from seventy patients with melancholic depression and forty healthy control subjects. Although imaging data were pre-processed with the 'new segment' algorithm, in order to obtain a comparison with previous segmentation approaches, tissue segmentation was also performed with the 'unified segmentation' approach. Melancholic patients showed a CSF volume increase in the region of the left Sylvian fissure, and a CSF volume decrease in the subarachnoid spaces surrounding medial and lateral parietal cortices. Furthermore, CSF increases in the left Sylvian fissure were negatively correlated with the reduction percentage of depressive symptoms at discharge. None of these results were replicated with the 'unified segmentation' approach. By contrast, between-group differences in the left Sylvian fissure were replicated with a non-automated quantification of the CSF content of this region. Left Sylvian fissure alterations reported here are in agreement with previous findings from non-automated CSF assessments, and also with other reports of gray and white matter insular alterations in depressive samples using automated approaches. The reliable characterization of CSF alterations may help in the comprehensive characterization of brain structural abnormalities in psychiatric samples and in the development of etiopathogenic hypotheses relating to the disorders

Cerebrospinal fluid space alterations in melancholic depression

Melancholic depression is a biologically homogeneous clinical entity in which structural brain alterations have been described. Interestingly, reports of structural alterations in melancholia include volume increases in Cerebro-Spinal Fluid (CSF) spaces. However, there are no previous reports of CSF volume alterations using automated whole-brain voxel-wise approaches, as tissue classification algorithms have been traditionally regarded as less reliable for CSF segmentation. Here we aimed to assess CSF volumetric alterations in melancholic depression and their clinical correlates by means of a novel segmentation algorithm ('new segment', as implemented in the software Statistical Parametric Mapping-SPM8), incorporating specific features that may improve CSF segmentation. A three-dimensional Magnetic Resonance Image (MRI) was obtained from seventy patients with melancholic depression and forty healthy control subjects. Although imaging data were pre-processed with the 'new segment' algorithm, in order to obtain a comparison with previous segmentation approaches, tissue segmentation was also performed with the 'unified segmentation' approach. Melancholic patients showed a CSF volume increase in the region of the left Sylvian fissure, and a CSF volume decrease in the subarachnoid spaces surrounding medial and lateral parietal cortices. Furthermore, CSF increases in the left Sylvian fissure were negatively correlated with the reduction percentage of depressive symptoms at discharge. None of these results were replicated with the 'unified segmentation' approach. By contrast, between-group differences in the left Sylvian fissure were replicated with a non-automated quantification of the CSF content of this region. Left Sylvian fissure alterations reported here are in agreement with previous findings from non-automated CSF assessments, and also with other reports of gray and white matter insular alterations in depressive samples using automated approaches. The reliable characterization of CSF alterations may help in the comprehensive characterization of brain structural abnormalities in psychiatric samples and in the development of etiopathogenic hypotheses relating to the disorders