The spontaneous brain activity of disgust: Perspective from resting state fMRI and resting state EEG.

In recent years, more and more studies on disgust have shown the association between disgust and various psychopathologies. Revealing the spontaneous brain activity patterns associated with disgust sensitivity from the perspective of individual differences will give us an insight into the neurologic nature of disgust and its psychopathological vulnerability. Here, we used two modal brain imaging techniques (resting fMRI and resting EEG) to reveal spontaneous brain activity patterns closely related to disgust sensitivity. The amplitude of low-frequency fluctuation results showed that disgust sensitivity is negatively correlated with the spontaneous activity of the right cerebellum crus II and positively correlated with the spontaneous activity of the right superior frontal cortex, which are inhibition-related brain regions. Furthermore, the microstate results of rest EEG indicated that the corrected duration, occurrence rate, and contribution of Class C, which is related to the anterior default mode network and is considered to be related to subjective representation of one' own body by combining interoceptive information with affective salience, were significantly positively correlated with the disgust sensitivity level. This data-driven approach provides the first evidence on the intrinsic brain features of disgust sensitivity based on two resting-state brain modalities. The results represent an initial effort to uncover the neurological basis of disgust sensitivity and its connection to psychopathology.

Functional parcellation of the default mode network: a large-scale meta-analysis.

The default mode network (DMN) consists of several regions that selectively interact to support distinct domains of cognition. Of the various sites that partake in DMN function, the posterior cingulate cortex (PCC), temporal parietal junction (TPJ), and medial prefrontal cortex (MPFC) are frequently identified as key contributors. Yet, it remains unclear whether these subcomponents of the DMN make unique contributions to specific cognitive processes and health conditions. To address this issue, we applied a meta-analytic parcellation approach used in prior work. This approach used the Neurosynth database and classification methods to quantify the association between PCC, TPJ, and MPFC activation and specific topics related to cognition and health (e.g., decision making and smoking). Our analyses replicated prior observations that the PCC, TPJ, and MPFC collectively support multiple cognitive functions such as decision making, memory, and awareness. To gain insight into the functional organization of each region, we parceled each region based on its coactivation pattern with the rest of the brain. This analysis indicated that each region could be further subdivided into functionally distinct subcomponents. Taken together, we further delineate DMN function by demonstrating the relative strengths of association among subcomponents across a range of cognitive processes and health conditions. A continued attentiveness to the specialization within the DMN allows future work to consider the nuances in sub-regional contributions necessary for healthy cognition, as well as create the potential for more targeted treatment protocols in various health conditions.

Higher Activation of the Rostromedial Prefrontal Cortex During Mental Stress Predicts Major Cardiovascular Disease Events in Individuals With Coronary Artery Disease.

BACKGROUND: Psychological stress is a risk factor for major adverse cardiovascular events (MACE) in individuals with coronary artery disease. Certain brain regions that control both emotional states and cardiac physiology may be involved in this relationship. The rostromedial prefrontal cortex (rmPFC) is an important brain region that processes stress and regulates immune and autonomic functions. Changes in rmPFC activity with emotional stress (reactivity) may be informative of future risk for MACE. METHODS: Participants with stable coronary artery disease underwent acute mental stress testing using a series of standardized speech/arithmetic stressors and simultaneous brain imaging with high-resolution positron emission tomography brain imaging. We defined high rmPFC activation as a difference between stress and control scans greater than the median value for the entire cohort. Interleukin-6 levels 90 minutes after stress, and high-frequency heart rate variability during stress were also assessed. We defined MACE as a composite of cardiovascular death, myocardial infarction, unstable angina with revascularization, and heart failure hospitalization. RESULTS: We studied 148 subjects (69% male) with mean±SD age of 62±8 years. After adjustment for baseline demographics, risk factors, and baseline levels of interleukin-6 and high-frequency heart rate variability, higher rmPFC stress reactivity was independently associated with higher interleukin-6 and lower high-frequency heart rate variability with stress. During a median follow-up of 3 years, 34 subjects (21.3%) experienced a MACE. Each increase of 1 SD in rmPFC activation with mental stress was associated with a 21% increase risk of MACE (hazard ratio, 1.21 [95% CI, 1.08-1.37]). Stress-induced interleukin-6 and high-frequency heart rate variability explained 15.5% and 32.5% of the relationship between rmPFC reactivity and MACE, respectively. Addition of rmPFC reactivity to conventional risk factors improved risk reclassification for MACE prediction, and C-statistic improved from 0.71 to 0.76 (P=0.03). CONCLUSIONS: Greater rmPFC stress reactivity is associated with incident MACE. Immune and autonomic responses to mental stress may play a contributory role.

Association of ovarian hormones with mapping concept of self and others in the brain's default mode network.

The brain's default mode network (DMN) has become closely associated with self-referential mental activity, particularly in the resting-state. Prior reports point that the sex hormones are potent modulators of brain plasticity and functional connectivity. However, it is uncertain whether changes in ovarian hormones, as occur during the monthly menstrual cycle, substantially affects the functional connectivity of DMN. Here, we employed a Self-Awareness Scale (SAS) and the resting-state functional MRI in the late follicular phase and the mid-luteal phase to investigate the effect of the estradiol (E2) and progesterone on the SAS and DMN. On the behavioral level, increased progesterone facilitated women's other-focused attention. The regions of interest-based resting-state functional connectivity analyses continued to demonstrate a negative correlation of the relative progesterone and the medial prefrontal cortex-inferior temporal gyrus (mPFC-ITG) functional connectivity, and a facilitated effect of relative E2 on the mPFC-inferior parietal lobule functional connectivity in the DMN. Furthermore, as a core hub of the 'theory of mind', the functional connectivity between the ITG and thalamus was found negatively correlated with the relative E2. Meanwhile, the mid-luteal phase, which had significantly lower relative E2 levels, was indicated had stronger ITG-thalamus functional connectivity during the resting state. These results demonstrated an opposite effect of E2 and progesterone on the DMN and the other-focused preference in the mid-luteal phase, extended previous evidence of the potentially adaptive psychological effects of ovarian hormones on mapping self and others in the brain networks.

Progesterone modulates theta oscillations in the frontal-parietal network.

The neuroactive metabolites of the steroid hormones progesterone (P4) and testosterone (T) are GABAergic modulators that influence cognition, yet, the specific effect of P4 and T on brain network activity remains poorly understood. Here, we investigated if a fundamental oscillatory network activity pattern, often related to cognitive control, frontal midline theta (FMT) oscillations, are modulated by steroids hormones, P4 and T. We measured the concentration of P4 and T using salivary enzyme immunoassay and FMT oscillations using high-density electroencephalography (EEG) during eyes-open resting-state in 55 healthy women and men. Electrical brain activity was analyzed using Fourier analysis, aperiodic signal fitting, and beamformer source localization. Steroid hormone concentrations and biological sex were used as predictors for scalp and source-estimated amplitude of theta oscillations. Elevated concentrations of P4 predicted increased amplitude of FMT oscillations across both sexes, and no relationship was found with T. The positive correlation with P4 was specific to the frontal midline electrodes and survived correction for the background aperiodic signal of the brain. Using source localization, FMT oscillations were localized to the frontal-parietal network (FPN). Additionally, theta amplitude within the FPN, but not the default mode network, positively correlated with P4 concentration. Our results suggest that P4 concentration modulates brain activity via upregulation of theta oscillations in the FPN.