OBJECTIVE: To investigate the effect of a short-term yoga-based lifestyle intervention on risk factors for cardiovascular disease (CVD) and markers of inflammation and endothelial function in overweight and obese men. DESIGN: Nonrandomized prospective lifestyle intervention study with pre-post design. SETTING AND LOCATION: Integral Health Clinic, an outpatient facility providing yoga-based lifestyle intervention programs for prevention and management of chronic diseases. SUBJECTS: Overweight and obese men (n=51) were enrolled in the study. Subjects who were physically unable to participate and those participating in other interventions were excluded from the study. INTERVENTION: A pretested intervention program including asanas (physical postures), pranayama (breathing exercises), group discussions, lectures, and individualized advice. OUTCOME MEASURES: The primary outcome measure was weight loss, and the secondary outcome measures were clinical and laboratory correlates of CVD risk, levels of interleukin-6 (IL-6), adiponectin, and endothelin-1 (ET-1). RESULTS: Men (n=51, body mass index [BMI] 26.26±2.42 kg/m(2)) were enrolled and underwent a yoga-based lifestyle intervention for 10 days. Of 51 subjects, 30 completed the study. There was a significant reduction in weight from Baseline to Day 10 (74.60±7.98, 72.69±8.37 kg, p<0.001, respectively), BMI (26.26±2.42, 25.69±2.47 kg/m(2), p<0.001, respectively), and systolic BP (121.73±11.58, 116.73±9.00, p=0.042, respectively). There was a significant reduction in plasma IL-6 from Baseline to Day 10 (median 2.24 vs. 1.26 pg/mL, respectively, p=0.012). There was a significant increase in the plasma adiponectin from Baseline to Day 10 (median 4.95 vs. 6.26 μg/mL, respectively, p=0.014). Plasma ET-1 level remained unchanged. CONCLUSION: These findings suggest that even a short-term yoga-based lifestyle intervention may be an important modality to reduce the risk for CVD as indicated by weight loss, reduction in systolic blood pressure, an increase in adiponectin, and decrease in IL-6 in overweight and obese men.
Despite growing evidence on the neural bases of emotion regulation, little is known about the mechanisms underlying individual differences in cognitive regulation of negative emotion, and few studies have used objective measures to quantify regulatory success. Using a trait-like psychophysiological measure of emotion regulation, corrugator electromyography, we obtained an objective index of the ability to cognitively reappraise negative emotion in 56 healthy men (Session 1), who returned 1.3 years later to perform the same regulation task using fMRI (Session 2). Results indicated that the corrugator measure of regulatory skill predicted amygdala-prefrontal functional connectivity. Individuals with greater ability to down-regulate negative emotion as indexed by corrugator at Session 1 showed not only greater amygdala attenuation but also greater inverse connectivity between the amygdala and several sectors of the prefrontal cortex while down-regulating negative emotion at Session 2. Our results demonstrate that individual differences in emotion regulation are stable over time and underscore the important role of amygdala-prefrontal coupling for successful regulation of negative emotion.
Although the co-occurrence of negative affect and pain is well recognized, the mechanism underlying their association is unclear. To examine whether a common self-regulatory ability impacts the experience of both emotion and pain, we integrated neuroimaging, behavioral, and physiological measures obtained from three assessments separated by substantial temporal intervals. Our results demonstrated that individual differences in emotion regulation ability, as indexed by an objective measure of emotional state, corrugator electromyography, predicted self-reported success while regulating pain. In both emotion and pain paradigms, the amygdala reflected regulatory success. Notably, we found that greater emotion regulation success was associated with greater change of amygdalar activity following pain regulation. Furthermore, individual differences in degree of amygdalar change following emotion regulation were a strong predictor of pain regulation success, as well as of the degree of amygdalar engagement following pain regulation. These findings suggest that common individual differences in emotion and pain regulatory success are reflected in a neural structure known to contribute to appraisal processes.
OBJECTIVE: The anticipation of adverse outcomes, or worry, is a cardinal symptom of generalized anxiety disorder. Prior work with healthy subjects has shown that anticipating aversive events recruits a network of brain regions, including the amygdala and anterior cingulate cortex. This study tested whether patients with generalized anxiety disorder have alterations in anticipatory amygdala function and whether anticipatory activity in the anterior cingulate cortex predicts treatment response. METHOD: Functional magnetic resonance imaging (fMRI) was employed with 14 generalized anxiety disorder patients and 12 healthy comparison subjects matched for age, sex, and education. The event-related fMRI paradigm was composed of one warning cue that preceded aversive pictures and a second cue that preceded neutral pictures. Following the fMRI session, patients received 8 weeks of treatment with extended-release venlafaxine. RESULTS: Patients with generalized anxiety disorder showed greater anticipatory activity than healthy comparison subjects in the bilateral dorsal amygdala preceding both aversive and neutral pictures. Building on prior reports of pretreatment anterior cingulate cortex activity predicting treatment response, anticipatory activity in that area was associated with clinical outcome 8 weeks later following treatment with venlafaxine. Higher levels of pretreatment anterior cingulate cortex activity in anticipation of both aversive and neutral pictures were associated with greater reductions in anxiety and worry symptoms. CONCLUSIONS: These findings of heightened and indiscriminate amygdala responses to anticipatory signals in generalized anxiety disorder and of anterior cingulate cortex associations with treatment response provide neurobiological support for the role of anticipatory processes in the pathophysiology of generalized anxiety disorder.
Fragile X syndrome (FXS) is the most commonly known genetic disorder associated with autism spectrum disorder (ASD). Overlapping features in these populations include gaze aversion, communication deficits, and social withdrawal. Although the association between FXS and ASD has been well documented at the behavioral level, the underlying neural mechanisms associated with the social/emotional deficits in these groups remain unclear. We collected functional brain images and eye-gaze fixations from 9 individuals with FXS and 14 individuals with idiopathic ASD, as well as 15 typically developing (TD) individuals, while they performed a facial-emotion discrimination task. The FXS group showed a similar yet less aberrant pattern of gaze fixations compared with the ASD group. The FXS group also showed fusiform gyrus (FG) hypoactivation compared with the TD control group. Activation in FG was strongly and positively associated with average eye fixation and negatively associated with ASD characteristics in the FXS group. The FXS group displayed significantly greater activation than both the TD control and ASD groups in the left hippocampus (HIPP), left superior temporal gyrus (STG), right insula (INS), and left postcentral gyrus (PCG). These group differences in brain activation are important as they suggest unique underlying face-processing neural circuitry in FXS versus idiopathic ASD, largely supporting the hypothesis that ASD characteristics in FXS and idiopathic ASD reflect partially divergent impairments at the neural level, at least in FXS individuals without a co-morbid diagnosis of ASD.
Chaotic conditions are a prevalent and threatening feature of social life. Five studies examined whether social class underlies divergent responses to perceptions of chaos in one's social environments and outcomes. The authors hypothesized that when coping with perceptions of chaos, lower class individuals tend to prioritize community, relative to upper class individuals, who instead tend to prioritize material wealth. Consistent with these predictions, when personally confronting chaos, lower class individuals were more communally oriented (Study 1), more connected with their community (Study 2), and more likely to volunteer for a community-building project (Study 3), compared to upper class individuals. In contrast, perceptions of chaos caused upper class individuals to express greater reliance on wealth (Study 4) and prefer financial gain over membership in a close-knit community (Study 5), relative to lower class individuals. These findings suggest that social class shapes how people respond to perceptions of chaos and cope with its threatening consequences.
Purpose Although quantitative benefits of mindfulness training have been demonstrated in youth, little is known about the processes involved. The aim of this study was to gain a detailed understanding of how young people engage with the ideas and practices known as mindfulness using qualitative enquiry. Methods Following completion of a six-week mindfulness training program with a nonclinical group of 11 young people (age 16–24), a focus group (N = 7) and open-ended interviews (n = 5) were held and audio-recorded. Qualitative data, collected at eight time points over three months from the commencement of training, were coded with the aid of computer software. Grounded theory methodology informed the data collection process and generation of themes and an explanatory model that captured participants' experiences. Results Participants described their daily lives as beset by frequent experiences of distress sometimes worsened by their unhelpful or destructive reactions. With mindfulness practice, they initially reported greater calm, balance, and control. Subsequently they commented on a clearer understanding of themselves and others. Mindfulness was then described as a “mindset” associated with greater confidence and competence and a lessened risk of future distress. Conclusions Participants demonstrated a sophisticated understanding of and engagement with mindfulness principles and practice. Their reported experience aligned well with qualitative research findings in adults and theoretical literature on mindfulness. An encouraging finding was that, with ongoing mindfulness practice and within a relatively short time, participants were able to move beyond improved emotion regulation and gain greater confidence in their ability to manage life challenges.
Concepts develop for many aspects of experience, including abstract internal states and abstract social activities that do not refer to concrete entities in the world. The current study assessed the hypothesis that, like concrete concepts, distributed neural patterns of relevant nonlinguistic semantic content represent the meanings of abstract concepts. In a novel neuroimaging paradigm, participants processed two abstract concepts (convince, arithmetic) and two concrete concepts (rolling, red) deeply and repeatedly during a concept-scene matching task that grounded each concept in typical contexts. Using a catch trial design, neural activity associated with each concept word was separated from neural activity associated with subsequent visual scenes to assess activations underlying the detailed semantics of each concept. We predicted that brain regions underlying mentalizing and social cognition (e.g., medial prefrontal cortex, superior temporal sulcus) would become active to represent semantic content central to convince, whereas brain regions underlying numerical cognition (e.g., bilateral intraparietal sulcus) would become active to represent semantic content central to arithmetic. The results supported these predictions, suggesting that the meanings of abstract concepts arise from distributed neural systems that represent concept-specific content.
Many investigators have hypothesized that brain response to cortisol is altered in depression. However, neural activation in response to exogenously manipulated cortisol elevations has not yet been directly examined in depressed humans. Animal research shows that glucocorticoids have robust effects on hippocampal function, and can either enhance or suppress neuroplastic events in the hippocampus depending on a number of factors. We hypothesized that depressed individuals would show 1) altered hippocampal response to exogenous administration of cortisol, and 2) altered effects of cortisol on learning. In a repeated-measures design, 19 unmedicated depressed and 41 healthy individuals completed two fMRI scans. Fifteen mg oral hydrocortisone (i.e., cortisol) or placebo (order randomized and double-blind) was administered 1 h prior to encoding of emotional and neutral words during fMRI scans. Data analysis examined the effects of cortisol administration on 1) brain activation during encoding, and 2) subsequent free recall for words. Cortisol affected subsequent recall performance in depressed but not healthy individuals. We found alterations in hippocampal response to cortisol in depressed women, but not in depressed men (who showed altered response to cortisol in other regions, including subgenual prefrontal cortex). In both depressed men and women, cortisol's effects on hippocampal function were positively correlated with its effects on recall performance assessed days later. Our data provide evidence that in depressed compared to healthy women, cortisol's effects on hippocampal function are altered. Our data also show that in both depressed men and women, cortisol's effects on emotional memory formation and hippocampal function are related.
Pseudoneglect is traditionally viewed as reflecting right hemisphere specialization for processing spatial information, resulting in orienting toward the contralateral, left, hemispace. Recent evidence suggests that healthy individuals differ from each other in both direction and magnitude of orienting bias, and moreover, the bias displayed by a person is consistent across time, suggesting that it may represent a trait of the individual. Animal studies reveal consistent orienting bias within an individual, which reflects asymmetry in dopaminergic brain systems. We measured basal D2-like receptor binding using positron emission tomography and the high-affinity ligand [F-18]fallypride, to test the hypothesis that asymmetry in dopaminergic neurotransmission in healthy humans modulates the orienting bias in humans. As predicted, we found that individual differences in the direction and magnitude of the orienting bias were strongly associated with the pattern of asymmetric binding of dopamine (DA) D2 receptors in the striatum, as well as clusters in the frontal and temporal cortex. These findings show for the first time that orienting bias reflects individual differences in the lateralization of DA systems in the healthy human brain.
Sensitivity, specificity, and reproducibility are vital to interpret neuroscientific results from functional magnetic resonance imaging (fMRI) experiments. Here we examine the scan-rescan reliability of the percent signal change (PSC) and parameters estimated using Dynamic Causal Modeling (DCM) in scans taken in the same scan session, less than 5 min apart. We find fair to good reliability of PSC in regions that are involved with the task, and fair to excellent reliability with DCM. Also, the DCM analysis uncovers group differences that were not present in the analysis of PSC, which implies that DCM may be more sensitive to the nuances of signal changes in fMRI data.
In this study, we tested the validity of 2 popular assumptions about empathy: (a) empathy can be enhanced by oxytocin, a neuropeptide known to be crucial in affiliative behavior, and (b) individual differences in prosocial behavior are positively associated with empathic brain responses. To do so, we measured brain activity in a double-blind placebo-controlled study of 20 male participants either receiving painful stimulation to their own hand (self condition) or observing their female partner receiving painful stimulation to her hand (other condition). Prosocial behavior was measured using a monetary economic interaction game with which participants classified as prosocial (N = 12) or selfish (N = 6), depending on whether they cooperated with another player. Empathy-relevant brain activation (anterior insula) was neither enhanced by oxytocin nor positively associated with prosocial behavior. However, oxytocin reduced amygdala activation when participants received painful stimulation themselves (in the nonsocial condition). Surprisingly, this effect was driven by "selfish" participants. The results suggest that selfish individuals may not be as rational and unemotional as usually suggested, their actions being determined by their feeling anxious rather than by reason.
Although individuals experience embarrassment as an unpleasant, negative emotion, the authors argue that expressions of embarrassment serve vital social functions, signaling the embarrassed individual's prosociality and fostering trust. Extending past research on embarrassment as a nonverbal apology and appeasement gesture, the authors demonstrate that observers recognize the expression of embarrassment as a signal of prosociality and commitment to social relationships. In turn, observers respond with affiliative behaviors toward the signaler, including greater trust and desire to affiliate with the embarrassed individual. Five studies tested these hypotheses and ruled out alternative explanations. Study 1 demonstrated that individuals who are more embarrassable also reported greater prosociality and behaved more generously than their less embarrassable counterparts. Results of Studies 2-5 revealed that observers rated embarrassed targets as being more prosocial and less antisocial relative to targets who displayed either a different emotion or no emotion. In addition, observers were more willing to give resources and express a desire to affiliate with these targets, and these effects were mediated by perceptions of the targets as prosocial.
According to the Conceptual Act Theory of Emotion, the situated conceptualization used to construe a situation determines the emotion experienced. A neuroimaging experiment tested two core hypotheses of this theory: (1) different situated conceptualizations produce different forms of the same emotion in different situations, (2) the composition of a situated conceptualization emerges from shared multimodal circuitry distributed across the brain that produces emotional states generally. To test these hypotheses, the situation in which participants experienced an emotion was manipulated. On each trial, participants immersed themselves in a physical danger or social evaluation situation and then experienced fear or anger. According to Hypothesis 1, the brain activations for the same emotion should differ as a function of the preceding situation (after removing activations that arose while constructing the situation). According to Hypothesis 2, the critical activations should reflect conceptual processing relevant to the emotion in the current situation, drawn from shared multimodal circuitry underlying emotion. The results supported these predictions and demonstrated the compositional process that produces situated conceptualizations dynamically.
Recent years have seen an explosion of interest in using neural oscillations to characterize the mechanisms supporting cognition and emotion. Oftentimes, oscillatory activity is indexed by mean power density in predefined frequency bands. Some investigators use broad bands originally defined by prominent surface features of the spectrum. Others rely on narrower bands originally defined by spectral factor analysis (SFA). Presently, the robustness and sensitivity of these competing band definitions remains unclear. Here, a Monte Carlo-based SFA strategy was used to decompose the tonic ("resting" or "spontaneous") electroencephalogram (EEG) into five bands: delta (1-5Hz), alpha-low (6-9Hz), alpha-high (10-11Hz), beta (12-19Hz), and gamma (>21Hz). This pattern was consistent across SFA methods, artifact correction/rejection procedures, scalp regions, and samples. Subsequent analyses revealed that SFA failed to deliver enhanced sensitivity; narrow alpha sub-bands proved no more sensitive than the classical broadband to individual differences in temperament or mean differences in task-induced activation. Other analyses suggested that residual ocular and muscular artifact was the dominant source of activity during quiescence in the delta and gamma bands. This was observed following threshold-based artifact rejection or independent component analysis (ICA)-based artifact correction, indicating that such procedures do not necessarily confer adequate protection. Collectively, these findings highlight the limitations of several commonly used EEG procedures and underscore the necessity of routinely performing exploratory data analyses, particularly data visualization, prior to hypothesis testing. They also suggest the potential benefits of using techniques other than SFA for interrogating high-dimensional EEG datasets in the frequency or time-frequency (event-related spectral perturbation, event-related synchronization/desynchronization) domains.
The capacity to stabilize the content of attention over time varies among individuals, and its impairment is a hallmark of several mental illnesses. Impairments in sustained attention in patients with attention disorders have been associated with increased trial-to-trial variability in reaction time and event-related potential deficits during attention tasks. At present, it is unclear whether the ability to sustain attention and its underlying brain circuitry are transformable through training. Here, we show, with dichotic listening task performance and electroencephalography, that training attention, as cultivated by meditation, can improve the ability to sustain attention. Three months of intensive meditation training reduced variability in attentional processing of target tones, as indicated by both enhanced theta-band phase consistency of oscillatory neural responses over anterior brain areas and reduced reaction time variability. Furthermore, those individuals who showed the greatest increase in neural response consistency showed the largest decrease in behavioral response variability. Notably, we also observed reduced variability in neural processing, in particular in low-frequency bands, regardless of whether the deviant tone was attended or unattended. Focused attention meditation may thus affect both distracter and target processing, perhaps by enhancing entrainment of neuronal oscillations to sensory input rhythms, a mechanism important for controlling the content of attention. These novel findings highlight the mechanisms underlying focused attention meditation and support the notion that mental training can significantly affect attention and brain function.
OBJECTIVES: The objectives of this study were to assess the general acceptability and to assess domains of potential effect of a mindfulness-based stress reduction (MBSR) program for human immunodeficiency virus (HIV)-infected and at-risk urban youth. METHODS: Thirteen-to twenty-one-year-old youth were recruited from the pediatric primary care clinic of an urban tertiary care hospital to participate in 4 MBSR groups. Each MBSR group consisted of nine weekly sessions of MBSR instruction. This mixed-methods evaluation consisted of quantitative data--attendance, psychologic symptoms (Symptom Checklist 90-Revised), and quality of life (Child Health and Illness Profile-Adolescent Edition)--and qualitative data--in-depth individual interviews conducted in a convenience sample of participants until interview themes were saturated. Analysis involved comparison of pre- and postintervention surveys and content analysis of interviews. RESULTS: Thirty-three (33) youth attended at least one MBSR session. Of the 33 who attended any sessions, 26 youth (79%) attended the majority of the MBSR sessions and were considered "program completers." Among program completers, 11 were HIV-infected, 77% were female, all were African American, and the average age was 16.8 years. Quantitative data show that following the MBSR program, participants had a significant reduction in hostility (p = 0.02), general discomfort (p = 0.01), and emotional discomfort (p = 0.02). Qualitative data (n = 10) show perceived improvements in interpersonal relationships (including less conflict), school achievement, physical health, and reduced stress. CONCLUSIONS: The data suggest that MBSR instruction for urban youth may have a positive effect in domains related to hostility, interpersonal relationships, school achievement, and physical health. However, because of the small sample size and lack of control group, it cannot be distinguished whether the changes observed are due to MBSR or to nonspecific group effects. Further controlled trials should include assessment of the MBSR program's efficacy in these domains.
This pilot study tested the efficacy of a brief intervention using motivational interviewing (MI) plus mindfulness meditation (MM) to reduce marijuana use among young adult females. Thirty-four female marijuana users between the ages of 18 and 29 were randomized to either the intervention group (n = 22), consisting of two sessions of MI-MM, or an assessment-only control group (n = 12). The participants' marijuana use was assessed at baseline and at 1, 2, and 3 months posttreatment. Fixed-effects regression modeling was used to analyze treatment effects. Participants randomized to the intervention group were found to use marijuana on 6.15 (z = -2.42, p = .015), 7.81 (z = -2.78, p = .005), and 6.83 (z = -2.23, p = .026) fewer days at Months 1, 2, and 3, respectively, than controls. Findings from this pilot study provide preliminary evidence for the feasibility and effectiveness of a brief MI-MM for young adult female marijuana users.
Our outside world changes continuously, for example, when driving through traffic. An important question is how our brain deals with this constant barrage of rapidly changing sensory input and flexibly selects only newly goal-relevant information for further capacity-limited processing in working memory. The challenge our brain faces is experimentally captured by the attentional blink (AB): an impairment in detecting the second of two target stimuli presented in close temporal proximity among distracters. Many theories have been proposed to explain this deficit in processing goal-relevant information, with some attributing the AB to capacity limitations related to encoding of the first target and others assigning a critical role to on-line selection mechanisms that control access to working memory. The current study examined the role of striatal dopamine in the AB, given its known role in regulating the contents of working memory. Specifically, participants performed an AB task and their basal level of dopamine D2-like receptor binding was measured using PET and [F-18]fallypride. As predicted, individual differences analyses showed that greater D2-like receptor binding in the striatum was associated with a larger AB, implicating striatal dopamine and mechanisms that control access to working memory in the AB. Specifically, we propose that striatal dopamine may determine the AB by regulating the threshold for working memory updating, providing a testable physiological basis for this deficit in gating rapidly changing visual information. A challenge for current models of the AB lies in connecting more directly to these neurobiological data.
Neuroimage phenotyping for psychiatric and neurological disorders is performed using voxelwise analyses also known as voxel based analyses or morphometry (VBM). A typical voxelwise analysis treats measurements at each voxel (e.g., fractional anisotropy, gray matter probability) as outcome measures to study the effects of possible explanatory variables (e.g., age, group) in a linear regression setting. Furthermore, each voxel is treated independently until the stage of correction for multiple comparisons. Recently, multi-voxel pattern analyses (MVPA), such as classification, have arisen as an alternative to VBM. The main advantage of MVPA over VBM is that the former employ multivariate methods which can account for interactions among voxels in identifying significant patterns. They also provide ways for computer-aided diagnosis and prognosis at individual subject level. However, compared to VBM, the results of MVPA are often more difficult to interpret and prone to arbitrary conclusions. In this paper, first we use penalized likelihood modeling to provide a unified framework for understanding both VBM and MVPA. We then utilize statistical learning theory to provide practical methods for interpreting the results of MVPA beyond commonly used performance metrics, such as leave-one-out-cross validation accuracy and area under the receiver operating characteristic (ROC) curve. Additionally, we demonstrate that there are challenges in MVPA when trying to obtain image phenotyping information in the form of statistical parametric maps (SPMs), which are commonly obtained from VBM, and provide a bootstrap strategy as a potential solution for generating SPMs using MVPA. This technique also allows us to maximize the use of available training data. We illustrate the empirical performance of the proposed framework using two different neuroimaging studies that pose different levels of challenge for classification using MVPA.
Responses to individuals who suffer are a foundation of cooperative communities. On the basis of the approach/inhibition theory of power (Keltner, Gruenfeld, & Anderson, 2003), we hypothesized that elevated social power is associated with diminished reciprocal emotional responses to another person's suffering (feeling distress at another person's distress) and with diminished complementary emotion (e.g., compassion). In face-to-face conversations, participants disclosed experiences that had caused them suffering. As predicted, participants with a higher sense of power experienced less distress and less compassion and exhibited greater autonomic emotion regulation when confronted with another participant's suffering. Additional analyses revealed that these findings could not be attributed to power-related differences in baseline emotion or decoding accuracy, but were likely shaped by power-related differences in the motivation to affiliate. Implications for theorizing about power and the social functions of emotions are discussed.
The present studies examined how observers infer moral attributes and beliefs from nonverbal pride displays. Pride is a self-focused positive emotion triggered by appraisals of the self's success, status, and competence. We hypothesized that when a target emits nonverbal cues of pride, he or she will be viewed by observers as higher in self-interest and therefore more likely to endorse ideologies that would benefit the self-specifically, merit-based resource distributions (meritocracy) as opposed to equality-based resource distributions (egalitarianism). Across studies, experimentally manipulated pride displays (Studies 1 and 3) and naturally occurring expressions of pride (Study 4) led observers to infer heightened support for meritocracy as opposed to egalitarianism. Analyses also revealed that people intuitively associate higher self-interest with enhanced support for meritocracy as opposed to egalitarianism (Study 2), and this association mediates the pathway from pride displays to inferences of heightened support for meritocracy and reduced support for egalitarianism (Studies 3 and 4). Across studies, we compare pride to expressions of joy or no emotion and demonstrate these effects using thin slices as well as static images.
BACKGROUND: Anhedonia, a reduced ability to experience pleasure, is a chief symptom of major depressive disorder and is related to reduced frontostriatal connectivity when attempting to upregulate positive emotion. The present study examined another facet of positive emotion regulation associated with anhedonia-namely, the downregulation of positive affect-and its relation to prefrontal cortex (PFC) activity. METHODS: Neuroimaging data were collected from 27 individuals meeting criteria for major depressive disorder as they attempted to suppress positive emotion during a positive emotion regulation task. Their PFC activation pattern was compared with the PFC activation pattern exhibited by 19 healthy control subjects during the same task. Anhedonia scores were collected at three time points: at baseline (time 1), 8 weeks after time 1 (i.e., time 2), and 6 months after time 1 (i.e., time 3). Prefrontal cortex activity at time 1 was used to predict change in anhedonia over time. Analyses were conducted utilizing hierarchical linear modeling software. RESULTS: Depressed individuals who could not inhibit positive emotion-evinced by reduced right ventrolateral prefrontal cortex activity during attempts to dampen their experience of positive emotion in response to positive visual stimuli-exhibited a steeper anhedonia reduction slope between baseline and 8 weeks of treatment with antidepressant medication (p < .05). Control subjects showed a similar trend between baseline and time 3. CONCLUSIONS: To reduce anhedonia, it may be necessary to teach individuals how to counteract the functioning of an overactive pleasure-dampening prefrontal inhibitory system.
Given the central role of the amygdala in fear perception and expression and its likely abnormality in affective disorders and autism, there is great demand for a technique to measure differences in neurochemistry of the human amygdala. Unfortunately, it is also a technically complex target for magnetic resonance spectroscopy (MRS) due to a small volume, high field inhomogeneity and a shared boundary with hippocampus, which can undergo opposite changes in response to stress. We attempted to achieve reliable PRESS-localized single-voxel MRS at 3T of the isolated human amygdala by using anatomy to guide voxel size and location. We present data from 106 amygdala-MRS sessions from 58 volunteers aged 10 to 52 years, including two tests of one-week stability and a feasibility study in an adolescent sample. Our main outcomes were indices of spectral quality, repeated measurement variability (within- and between-subject standard deviations), and sensitivity to stable individual differences measured by intra-class correlation (ICC). We present metrics of amygdala-MRS reliability for n-acetyl-aspartate, creatine, choline, myo-Inositol, and glutamate+glutamine (Glx). We found that scan quality suffers an age-related difference in field homogeneity and modified our protocol to compensate. We further identified an effect of anatomical inclusion near the endorhinal sulcus, a region of high synaptic density, that contributes up to 29% of within-subject variability across 4 sessions (n=14). Remaining variability in line width but not signal-to-noise also detracts from reliability. Statistical correction for partial inclusion of these strong neurochemical gradients decreases n-acetyl-aspartate reliability from an intraclass correlation of 0.84 to 0.56 for 7-minute acquisitions. This suggests that systematic differences in anatomical inclusion can contribute greatly to apparent neurochemical concentrations and could produce false group differences in experimental studies. Precise, anatomically-based prescriptions that avoid age-related sources of inhomogeneity and use longer scan times may permit study of individual differences in neurochemistry throughout development in this late-maturing structure.
The development of functional neuroimaging of emotion holds the promise to enhance our understanding of the biological bases of affect and improve our knowledge of psychiatric diseases. However, up to this point, researchers have been unable to objectively, continuously and unobtrusively measure the intensity and dynamics of affect concurrently with functional magnetic resonance imaging (fMRI). This has hindered the development and generalizability of our field. Facial electromyography (EMG) is an objective, reliable, valid, sensitive, and unobtrusive measure of emotion. Here, we report the successful development of a method for simultaneously acquiring fMRI and facial EMG. The ability to simultaneously acquire brain activity and facial physiology will allow affective neuroscientists to address theoretical, psychiatric, and individual difference questions in a more rigorous and generalizable way.
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