Left Dorsal Anterior Cingulate Cortex Research Articles

Dissociable neural correlates of spatial attention and response inhibition in spatially driven interference

Neural mechanisms underlying response inhibition have been investigated using spatially driven interference tasks such as the arrow-word Stroop task. However, neural responses, which are observed in the arrow-word Stroop task, may reflect not only response inhibition, but spatial attention modulation as well due to the spatial properties of an arrow stimulus. The current study aimed to identify whether individual cortical regions associated with spatially driven interference contribute to either spatial attention modulation or response inhibition, or both. We therefore developed a new task that measures these two functions independently and then conducted a functional magnetic resonance imaging experiment. Our results indicate that the right inferior parietal lobule and precentral gyrus were engaged by the spatial attention modulation, while inhibition was closely associated with the bilateral inferior frontal gyri, aided by the left superior prefrontal gyrus and dorsal anterior cingulate cortex. The left inferior parietal lobule was associated with common processes engaged in allocating attentional resources. These findings provide new evidence that spatially driven interference may recruit distinct cortical regions involved in spatial attention modulation and/or response inhibition.

Metacognition-related regions modulate the reactivity effect of confidence ratings on perceptual decision-making

Prompting confidence ratings following perceptual decision-making could significantly affect the decision-making per se, a phenomenon known as the reactivity effect. The current study aimed to explore the neural substrates underlying the reactivity effect by comparing behavioral and functional magnetic imaging data between when participants making decisions with prompted confidence ratings (DCR+) and when without providing confidence ratings (DCR−). The results showed that DCR+ was associated with longer decision response times (RTs) and higher accuracy than DCR−. The analysis of fMRI data revealed significantly increased activation in the DCR+ condition, relative to the DCR− condition, in multiple metacognition-related regions including the left supplementary motor area, left dorsal anterior cingulate cortex, left opercular part of the inferior frontal gyrus, and bilateral precuneus. Changed beta values (BetaDCR+ minus BetaDCR−) of these clusters were correlated with the changed decision RTs between the two conditions (ΔRT = RTDCR+ − RTDCR−). Psychophysiological interaction analysis revealed increased functional connectivity between the left supplementary motor area and the right inferior parietal lobe in the DCR+ condition than the DCR− condition. Further multiple regression analysis found that ΔRTs was significantly associated with activities in the bilateral dorsal anterior cingulate cortex and supplementary motor area. Together, this study found that provide confidence ratings significantly changed online decision-making while activating multiple metacognition-related regions. The activity of metacognition-related regions may be a crucial part of the neural mechanisms underlying the reactivity effect of confidence ratings on perceptual decision-making.

Changed Resting-State Brain Signal in Parkinson's Patients With Mild Depression.

Background: Depression is reported to occur 5–10 years early than the onset of motor symptoms in Parkinson (PD) patients. However, markers for early diagnosis of PD in individuals with sub-clinical depression still remain to be identified.Purpose: This study utilized Regional Homogeneity (ReHo) to investigate the alterations in resting state brain activities in Parkinson (PD) patients with different degrees of depression.Methods: Twenty non-depressed PD patients, twenty mild to moderately depressed PD patients, and thirteen severely depressed PD patients were recruited. Hamilton Depression Scale (HDS) and the Beck Depression Inventory (BDI) were assessed depression. Resting-state functional magnetic resonance imaging (rs-MRI) was analyzed with ReHo.Results: PD patients with mild to moderate depression had decreased ReHo in the left dorsal anterior cingulate cortex when compared with PD patients without depression. PD patients with severe depression exhibited increased ReHo in the left inferior prefrontal gyrus and right orbitofrontal area when compared with PD patients with mild to moderate depression. ReHo values in the bilateral supplementary motor area (SMA) in PD patients with severe depression was also increased when compared with PD patients without depression.Conclusions: This study suggests that rs-MRI with ReHo analysis can detect early changes in brain function that associate with depression in PD patients, which could be biomarkers for early diagnosis and treatment of PD related depression.

Altered neural processing of negative stimuli in people with internet gaming disorder: fMRI evidence from the comparison with recreational game users

BackgroundAbundant clinical studies have suggested that emotion dysregulation seems to be the essential pathogenesis for Internet gaming disorder (IGD). However, the neural mechanism of emotion regulation for IGD is still unclear. MethodsSubjective evaluation and fMRI data were collected from 50 subjects (IGD: 24; recreational game user (RGU): 26) while they were performing an emotion reappraisal task. We collected and compared their brain features during emotion processing of different visual stimuli. ResultsHigher activation in the left dorsal anterior cingulate cortex (dACC), right ventral ACC, left claustrum and bilateral insula was observed in participants with IGD during emotion reappraisal relative to that of the RGU participants. In addition, generalized psychophysiological interaction analysis also showed that IGD participants had stronger functional connectivity between the right insula and bilateral dorsolateral prefrontal cortex (DLPFC) than the RGU participants. ConclusionsThe results suggest that IGD participants could not down-regulate their negative emotional experiences as efficiently as the RGU participants, although they engaged more cognitive resources. These results reveal the special neural circuits of emotion dysregulation in IGD individuals and provide new neural perspective for the intervention of IGD.

Opponent Effects of Hyperarousal and Re-experiencing on Affective Habituation in Posttraumatic Stress Disorder

BackgroundAberrant emotion processing is a hallmark of posttraumatic stress disorder (PTSD), with neurobiological models suggesting both heightened neural reactivity and diminished habituation to aversive stimuli. However, empirical work suggests that these response patterns may be specific to subsets of those with PTSD. This study investigates the unique contributions of PTSD symptom clusters (re-experiencing, avoidance and numbing, and hyperarousal) to neural reactivity and habituation to negative stimuli in combat-exposed veterans. MethodsNinety-five combat-exposed veterans (46 with PTSD) and 53 community volunteers underwent functional magnetic resonance imaging while viewing emotional images. This study examined the relationship between symptom cluster severity and hemodynamic responses to negative compared with neutral images (NEG>NEU). ResultsVeterans exhibited comparable mean and habituation-related responses for NEG>NEU, relative to civilians. However, among veterans, habituation, but not mean response, was differentially related to PTSD symptom severity. Hyperarousal symptoms were related to decreased habituation for NEG>NEU in a network of regions, including superior and inferior frontal gyri, ventromedial prefrontal cortex, superior and middle temporal gyri, and anterior insula. In contrast, re-experiencing symptoms were associated with increased habituation in a similar network. Furthermore, re-experiencing severity was positively related to amygdalar functional connectivity with the left inferior frontal gyrus and dorsal anterior cingulate cortex for NEG>NEU. ConclusionsThese results indicate that hyperarousal symptoms in combat-related PTSD are associated with decreased neural habituation to aversive stimuli. These impairments are partially mitigated in the presence of re-experiencing symptoms, such that during exposure to negative stimuli, re-experiencing symptoms are positively associated with amygdalar connectivity to prefrontal regions implicated in affective suppression.

Antidepressant and antisuicidal effects of ketamine on the functional connectivity of prefrontal cortex-related circuits in treatment-resistant depression: A double-blind, placebo-controlled, randomized, longitudinal resting fMRI study

BackgroundIncreasing evidence suggests that infusion of a subanesthetic dose of ketamine exerts antidepressant and antisuicidal effects in patients with treatment-resistant depression (TRD). AimsIn this investigation, we used the resting functional connectivity magnetic resonance imaging (fcMRI) to determine the effects of ketamine on the functional connectivity (FC) of prefrontal cortex (PFC)–related circuits in patients with TRD. MethodsForty-eight patients with TRD were recruited and randomly divided into three groups on the basis of ketamine infusion dose: 0.5 mg/kg (standard dose), 0.2 mg/kg (low dose), or normal saline (a placebo infusion). Resting functional MRI data and clinical data were recorded at the baseline and on the third day after ketamine infusion treatment. ResultsThe standard-dose group showed a reduction in the FC of the left dorsal anterior cingulate cortex (dACC) and right dorsolateral (dl)PFC with the other frontal regions. The low-dose group demonstrated a more pervasive reduction of FC in the bilateral dACC with other frontal and parietal regions. A negative correlation was observed between the reduction in suicidal ideation and the reduction in the FC between the left dACC and right ACC regions in the standard-dose group, whereas a positive correlation was observed between the reduction in suicidal ideation and the increase in the FC between the right dlPFC and left superior parietal region in the low-dose group. ConclusionsOur results support the hypothesis that PFC-related circuit modulation is crucial to the antidepressant and antisuicidal effects of the ketamine infusion treatment.

Extreme spicy food cravers displayed increased brain activity in response to pictures of foods containing chili peppers: an fMRI study

In China, the rate of spicy food consumption is rising, and chili pepper is among the most popular spicy foods consumed nationwide. Therefore, investigation into spicy food craving is of public health interest and can also provide better insights into the mechanisms that underlie food cravings more generally. This exploratory study aimed to determine neural circuits underlying spicy food craving by comparing brain response to the cues of foods containing chili peppers in extreme cravers and non-cravers defined by scores on the Spicy Food Craving Questionnaire. A group of extreme cravers (n = 25) and a group of age- and sex-matched non-cravers (n = 26) participated in an fMRI event-related cue-reactivity paradigm, during which pictures of foods with visible chili peppers and pictures of foods with no chili peppers were presented. Results showed that extreme spicy food cravers exhibited increased activation in bilateral insula, left putamen, left dorsal anterior cingulate cortex, right inferior parietal lobule, right lingual gyrus, bilateral cuneus, left precuneus, left fusiform gyrus, and right precentral gyrus compared to non-cravers when exposed to the cues of foods containing chili versus foods without chili. While we did not observe the differential activation of orbitofrontal cortex and amygdala of this contrast in extreme cravers compared to non-cravers. Changes in beta values within the right insula, left putamen, left dorsal anterior cingulate cortex and left precuneus were positively associated with subjective spicy food craving during the scan among extreme cravers. In addition, changes in beta values within right inferior parietal lobule was significantly correlated with the frequency of spicy food intake among extreme cravers. These results align with prior work suggesting that the dorsal striatum, the anterior cingulate cortex and the insula underlie food craving.

Relationship of negative urgency to cingulo-insular and cortico-striatal resting state functional connectivity in tobacco use.

Negative urgency, defined as a tendency to act rashly under extreme negative emotion, is strongly associated with tobacco use. Despite the robust evidence linking negative urgency and tobacco use and accumulating evidence suggesting that localized, segregated brain regions such as the nucleus accumbens (NAcc), insula, and amygdala are related to negative urgency, resting state functional connectivity (rsFC) of negative urgency in tobacco use has not yet been examined. This study included 34 daily tobacco users and 62 non-users matched on age, gender, race/ethnicity, and lifetime psychiatric diagnosis from a publicly available neuroimaging dataset collected by the Nathan Kline Institute-Rockland Project. Using the bilateral NAcc, insula, and amygdala as seed regions, seed-based rsFC analyses were conducted on the whole brain. In the whole sample, negative urgency was positively correlated with rsFC between the left insula and right dorsal anterior cingulate cortex (dACC). Compared to non-users, tobacco users had a stronger rsFC strength between the right amygdala and right middle temporal gyrus. In tobacco users, negative urgency was negatively associated with rsFC between the left NAcc and right dACC and between the left NAcc and right dorsolateral prefrontal cortex; these relationships were positive in non-users. Identifying functional connectivity implicated in negative urgency and tobacco use is the crucial first step to design and test pharmacological and physiological interventions to reduce negative urgency related tobacco use.

The road towards personalized medicine: Increasing the effects of brain stimulation using individual characteristics

Non-invasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have shown high treatment potential for a broad variety of neuropsychiatric disorders. However, the application of ‘standard’ protocols results in high inter-individual differences in the responses and reduce the overall efficacy. In this symposium, individual characteristics that are linked to the clinical outcome of stimulation treatment will be highlighted. It can be hypothesized that inter-individual differences in responses to stimulation can be assigned to variations in individual neurocircuitries. Therefore, the first two presentations will focus on functional connectivities (FC) on network level. Firstly, the use of graph analysis to study the effect of accelerated intermittent theta burst stimulation (aiTBS) is explained (n = 50, major depressive disorder patients). Also it will be shown that baseline graph measures can predict the clinical efficacy of this stimulation protocol. Clinical efficacy in this case was derived from the 17-item Hamilton questionnaire. Secondly, the influence of different stimulation positions, derived from FC within two different networks, on the effect of one iTBS session on an n-back task will be presented (n = 12, healthy subjects). Being more or less vulnerable to psychopathology can also affect the outcome of NIBS. For example, the tendency to ruminate in daily life influences the outcome of iTBS (n = 38, healthy subjects). Here, the effect of iTBS was quantified using cortisol recovery. Moreover, the application of prefrontal tDCS before listening to self-referent criticism affects FC between the left dorsal anterior cingulate cortex and the right dorsomedial prefrontal cortex distinctively in healthy women low versus high in perceived criticism (n = 46). In conclusion, this symposium will show that individual mechanisms play a role in the effect of NIBS. Therefore, in future protocols, personalized characteristics might enhance clinical efficacy.

Resting-state functional connectivity in medication-naïve adolescents with major depressive disorder

Adolescence is a vulnerable period for major depressive disorder (MDD). The aim of our study was to investigate resting-state functional connectivity (RSFC) in first-episode, medication-naïve adolescent MDD patients. Twenty-three drug-naïve adolescents diagnosed with first-episode MDD and 27 healthy participants were enrolled. Seed-to-voxel RSFC analyses were performed. The frontolimbic circuit regions of interest included the amygdala, anterior cingulate cortex, insula, and hippocampus. A correlation analysis between the RSFC and Children's Depression Inventory, Hamilton depression rating scale, and duration of episodes was performed. The adolescents with MDD exhibited the following characteristics: a lower RSFC between the right amygdala and right superior frontal gyrus; a lower RSFC between the right hippocampus and clusters including the right insula and right middle frontal gyrus; a higher RSFC between the left insula and clusters including the bilateral middle frontal gyrus, right superior frontal gyrus, and right frontal pole; and a higher RSFC between the left dorsal anterior cingulate cortex and a cluster including the left insula. Medication-naïve adolescents with depression display lower connectivity of several brain regions implicated in processing, regulation, and memory of emotions. Higher connectivity was observed in brain regions that potentially explain rumination, impaired concentration, and physiological arousal.

Transcranial Direct Current Stimulation for Affective Symptoms and Functioning in Chronic Low Back Pain: A Pilot Double-Blinded, Randomized, Placebo-Controlled Trial.

Chronic low back pain (CLBP) is highly prevalent, with a substantial psychosocial burden. Pain has both sensory and affective components. The latter component is a significant driver of disability and psychiatric comorbidity but is often inadequately treated. Previously we reported that noninvasive transcranial direct current stimulation (tDCS) may modulate pain-associated affective distress. Here we tested whether 10 daily tDCS sessions aimed to inhibit the left dorsal anterior cingulate cortex (dACC), a region strongly implicated in the affective component of pain, would produce selective reduction in pain-related symptoms. In this multisite, double-blinded, randomized placebo-controlled trial (RCT), 21 CLBP patients received 10 weekday sessions of 2-mA active tDCS or sham (20 minutes/session). A cathodal electrode was placed over FC1 (10-20 electroencephalography coordinates), and an identical anodal return electrode was placed over the contralateral mastoid. Participants rated pain intensity, acceptance, interference, disability, and anxiety, plus general anxiety and depression. Regression analysis noted significantly less pain interference (P =0.002), pain disability (P =0.001), and depression symptoms (P =0.003) at six-week follow-up for active tDCS vs sham. Omnibus tests suggested that these improvements were not merely due to baseline (day 1) group differences. To our knowledge, this is the first double-blinded RCT of multiple tDCS sessions targeting the left dACC to modulate CLBP's affective symptoms. Results are encouraging, including several possible tDCS-associated improvements. Better-powered RCTs are needed to confirm these effects. Future studies should also consider different stimulation schedules, additional cortical targets, high-density multi-electrode tDCS arrays, and multimodal approaches.

Involvement of the Cingulate Cortex in Anosognosia: A Multimodal Neuroimaging Study in Alzheimer's Disease Patients.

Background:Anosognosia is a frequent symptom of Alzheimer’s disease (AD), but its neural substrates remain in question.Objective:In this study, we combined neuroimaging with a neuropsychological evaluation to assess neural substrates of anosognosia.Methods:We prospectively recruited 30 patients with probable early-stage AD and matched healthy controls. Participants underwent MRI, FDG-PET, and a neuropsychological evaluation that includes an assessment of anosognosia. In the AD group, correlations between the anosognosia score, neuroimaging modalities, and neuropsychological performance were performed.Results:Atrophy and hypometabolism were correlated with the anosognosia score in the left dorsal anterior cingulate cortex. The anosognosia score was also correlated with atrophy of the cerebellar vermis, the left postcentral gyrus, and the right fusiform gyrus. No relation was found between anosognosia and the neuropsychological assessment.Discussion:Structural and metabolic alteration in the dorsal anterior cingulate cortex seems to be associated with a diminution of awareness in patients with early-stage AD.

Prefrontal TDCS attenuates medial prefrontal connectivity upon being criticized in individuals scoring high on perceived criticism.

The mechanisms by which transcranial direct current stimulation (tDCS) influences emotional processing - and whether this is related to individual vulnerability for psychopathology - are still poorly understood. The present study aimed to investigate if one prefrontal tDCS session modulates mood and neural functional connectivity after being exposed to negative information differently in individuals low or high in perceived criticism (PC), which has been related to vulnerability for psychiatric illness. In a randomized cross-over design, one session of MRI-compatible prefrontal tDCS (neuronavigated placement of the anodal electrode at the left dorsolateral prefrontal cortex and the cathodal electrode at the right supraorbital region; vs. sham) was administered to healthy females, prior to listening to self-referential criticism. PC-dependent (low vs. high PC) changes in mood and resting-state functional connectivity patterns following tDCS and after hearing criticism were explored. After being criticized all females (low and high PC) felt angrier and more depressed, both in the active tDCS or sham tDCS condition. However, in contrast to low PC females, in high PC females prefrontal tDCS reduced connectivity between the left dorsal anterior cingulate cortex and the right dorsomedial prefrontal cortex following criticism. Despite having no differential effects on self-reported mood, prefrontal tDCS reduces medial prefrontal neural connectivity after being criticized in high PC females compared to low PC females. Depending on individual vulnerability for psychopathology, a single tDCS session differentially affects neural processing of negative emotional information, especially in brain regions involved in monitoring, experiencing and appraising/evaluating emotional material.

T187. Transcranial Direct Current Stimulation (tDCS) for the Affective Symptoms of Chronic Low Back Pain (CLBP): A Double-Blinded, Randomized, Placebo-Controlled Trial

“Pain” has sensory and affective (emotional) components. CLBP’s affective symptoms underlie associated disability and psychiatric comorbidity and have limited treatments (e.g. cognitive behavioral therapy); consequently, there is over-reliance on opioid analgesics with deleterious side effects. tDCS may noninvasively modulate pain-related affective distress. We present full analysis of a first multi-site, double-blinded, randomized placebo-controlled trial (RCT) of tDCS targeting left dorsal anterior cingulate cortex, a region implicated in pain’s affective component, in CLBP patients.

The neural correlates of apathy in schizophrenia: An exploratory investigation

BackgroundMotivational deficits represent a core negative symptom in patients with schizophrenia. Previous morphology studies have demonstrated that apathy in patients with schizophrenia is associated with reduced frontal grey matter (GM). We attempted to replicate this previous finding, and explored whether it was distinct from potential associations with a distinct subdomain of negative symptoms, namely Affective Flattening, and GM. MethodsTwenty medicated patients with schizophrenia provided structural T1-weighted images acquired on a 3-Tesla MRI scanner and negative symptoms were evaluated using the Scale for the Assessment of Negative Symptoms. Voxel-based morphometry (VBM) was used to explore the correlations between whole-brain GM and i) Apathy, and ii) Affective Flattening, respectively. ResultsApathy scores were negatively correlated with several GM clusters in frontal regions, including the frontal inferior operculum and the left dorsal anterior cingulate cortex. Only positive correlations with GM clusters were observed for Affective Flattening, particularly in the inferior temporal lobe. Notably, the regions associated with apathy scores were distinct from those associated with Affective Flattening, and these findings remained after controlling for antipsychotic medication dosage. ConclusionsWe replicated previous associations between reduced frontal GM and apathy in patients with schizophrenia. Moreover, we demonstrated that these GM associations are distinct from those with Affective Flattening. The present findings set the stage for future larger-scale studies confirming the structural and neurochemical substrates of apathy in schizophrenia.

Changes of brain function and cognitive function after carotid artery stenting

Objective: To investigate the effect of carotid artery stenting(CAS) on cognitive function and brain function based on changes of a battery of neuropsychological tests and magnetic resonance imaging. Methods: Thirty-three patients were included with 17 in the stent-placement group and 16 in the control group (receiving medical treatment), among whom, the unilateral or bilateral severe internal carotid artery stenosis was confirmed by cerebral vascular angiography in the department of Interventional Radiology and Vascular Surgery of Zhongda Hospital Southeast University from June 2015 to September 2016.Neuropsychological tests and rest-state blood oxygenation level dependent fMRI were performed at the baseline and six months follow-up.The baseline characteristics and follow-up changes were compared in each group. Results: The overall cognitive function of the stent-placement group was statistically significantly improved (P<0.05) compared with control group, mainly in the executive function, memory, attention and other aspects.The value of amplitude of low-frequency fluctuation(ALFF) showed statistically significant increase (P<0.05, Alphasim correction) in left prefrontal cortex (t=5.861 3, P<0.05), the somatosensory association cortex in left superior parietal lobe(t=5.601 2, P<0.05) and bilateral motor cortical area in posterior frontal lobe (t=5.288 5, P<0.05). The ALFF showed statistically significant decrease (P<0.05, Alphasim correction) in left retrosplenial cingulate cortex(t=-5.590 4, P<0.05), left insular cortex (t=-6.340 8, P<0.05), right insular cortex (t=-8.129 9, P<0.05) and left dorsal anterior cingulate cortex (t=-5.584 8, P<0.05). There was no statistically significant difference (P>0.05, Alphasim correction)between baseline and follow-up results in control group.Besides, the ALFF changes of the left insular cortex (r=-0.591, P=0.033) and bilateral motor cortical area (r=-0.659, P=0.014) were negatively correlated with auditory verb learning test (AVLT) score changes.The ALFF change of bilateral motor cortical area was negatively correlated with the AVLT-delay score change (r=-0.588, P=0.034). And the ALFF change on right insular cortex and the frontal assessment battery (FAB) score change was positively correlated (r=0.638, P=0.025). Conclusions: The overall cognitive function of patients with carotid artery stenosis significantly improve after CAS compared with medical treatment.The change of ALFF value in related brain area is also statistically significant.ALFF Change most in area of Default Mode Network may suggest a mechanism of postoperative neurological recovery in patients with carotid artery stenosis.

Cerebral Blood Flow after Mild Traumatic Brain Injury: Associations between Symptoms and Post-Injury Perfusion

Arterial spin labeling (ASL) has emerged as a technique for assessing mild traumatic brain injury (mTBI), as it can noninvasively evaluate cerebrovascular physiology. To date, there is substantial variability in methodology and findings of ASL studies of mTBI. While both increased and decreased perfusion are reported after mTBI, more consistency is emerging when perfusion is examined with regard to symptomology. We evaluated 15 teenage athletes two and six weeks after sports-related concussion (SRC group) using pseudo-continuous ASL. We acquired comparison data from 15 matched controls from a single time point. At each time point, we completed whole-brain contrasts to evaluate differences between the SRC group and controls in relative cerebral blood flow (rCBF). Cluster-level findings directed region of interest (ROI) analyses to test for group differences in rCBF across the left dorsal anterior cingulate cortex (ACC) and left insula. Finally, we evaluated ROI rCBF and symptomology in the SRC group. At two weeks post-injury, the SRC group had significantly higher rCBF in the left dorsal ACC and left insula than controls; at six weeks post-injury, elevated rCBF persisted in the SRC group in the left dorsal ACC. Perfusion in the left dorsal ACC was higher in athletes reporting physical symptoms six weeks post-injury compared with asymptomatic athletes and controls. Overall, these findings are inconsistent with reports of reduced rCBF after mTBI but coherent with studies that report increased perfusion in persons with greater or persistent mTBI-related symptomology. Future work should continue to assess how CBF perfusion relates to symptomology and recovery after mTBI.

Deviant functional activation and connectivity of the right insula are associated with lack of awareness of episodic memory impairment in nonamnesic alcoholism

A disorder of metamemory, expressed as unawareness of mnemonic ability, is typically associated with the profound amnesia of Korsakoff's Syndrome (KS). A similar but less severe type of limited awareness can also occur in non-KS alcoholism and is observed as an impairment in generating Feeling-of-Knowing (FOK) predictions about future recognition performance. We previously found that FOK accuracy was selectively related to volumes of the insula in alcoholics involved in the present study. Unknown, however, are the neural substrates of unawareness of memory impairment in alcoholism. A task-activated fMRI paradigm served to identify neural nodes and networks implicated in inaccurate self-estimation of mnemonic ability in sober alcoholics while they made prospective FOK judgments in an episodic memory paradigm. Lower activation in the right insula correlated with greater overestimations of future memory abilities in alcoholics. Weaker connectivity of the right insula with the left dorsal anterior cingulate cortex, a node of the salience network, and stronger connectivity of the right insula with the right ventromedial prefrontal cortex (vmPFC), a node of the default mode network (DMN), co-occurred in alcoholics relative to the controls. Specifically, alcoholics, who failed to desynchronize insula-vmPFC activity, had greater overestimation of their memory predictions and poorer recognition performance. This study provides novel support that deviant functional activation and connectivity involving the right insula, a hub of the salience network, appears to participate in disrupting metamemory functioning in alcoholics. Compromised FOK performance might result from disturbance of the switching mechanism between brain networks serving self-referential processes (i.e., DMN network) and networks serving externally-driven activities like memory monitoring (i.e., fronto-parietal network). Thus, compromise in insular network coupling could be a neural mechanism underlying anosognosia for subtle mnemonic impairment in nonamnesic alcoholism.

Cortical Surface Thickness in the Middle-Aged Brain with White Matter Hyperintense Lesions.

Background and purpose: Previous voxel-based morphometry (VBM) studies have suggested that cortical atrophy is regionally distributed in middle-aged subjects with white matter hyperintense (WMH) lesions. However, few studies have assessed cortical thickness in middle-aged WMH subjects. In this study, we examined cortical thickness as well as cortical morphometry associated with the presence of WMH lesion load in middle-aged subjects.Participants and methods: Thirty-six middle-aged subjects with WMH lesions (WMH group) and without clinical cognitive impairment, and 34 demographically matched healthy control subjects (HCS group) participated in the study. Cortical thickness was estimated using an automated Computational Anatomy Toolbox (CAT12) as the distance between the gray-white matter border and the pial surface. Individual WMH lesions were manually segmented, and WMH loads were measured. Statistical cortical maps were created to estimate differences in cortical thickness between groups based on this cortex-wide analysis. The relationship between WMH lesion loads and cerebral cortical thickness was also analyzed in CAT12.Results: Cortical thickness was significantly lower in the WMH group than in the controls in multimodal integration regions, including the right and left dorsal anterior cingulate cortex (dACC), right and left frontal operculum (fO), right and left operculum parietale (OP), right and left middle temporal gyrus (MTG), and left superior temporal gyrus (STG; P < 0.01, family-wise error (FWE)-corrected). Additionally, cortical thickness was also lower in the recognition regions that contained the right temporal pole (TP), the right and left fusiform gyrus, and the left rolandic operculum (RO; P < 0.01, FWE-corrected). The results revealed that in the left superior parietal lobule (SPL), cortical thickness was higher in the WMH group than in the HCS group (P < 0.01, FWE-corrected). A voxel-wise negative correlation was found between cortical thickness and WMH lesion loads in the right orbitofrontal cortex (OFC), right dorsolateral prefrontal cortex (DLPFC), and right subcallosal cortex (P < 0.01, FWE-corrected).Conclusion: The main findings of this study suggest that middle-aged WMH subjects are more likely to exhibit cortical thinning, especially in multimodal integration and recognition- and motor-related regions. The current morphometry data provide further evidence for WMH-associated structural plasticity.

Effects of gratitude meditation on neural network functional connectivity and brain-heart coupling

A sense of gratitude is a powerful and positive experience that can promote a happier life, whereas resentment is associated with life dissatisfaction. To explore the effects of gratitude and resentment on mental well-being, we acquired functional magnetic resonance imaging and heart rate (HR) data before, during, and after the gratitude and resentment interventions. Functional connectivity (FC) analysis was conducted to identify the modulatory effects of gratitude on the default mode, emotion, and reward-motivation networks. The average HR was significantly lower during the gratitude intervention than during the resentment intervention. Temporostriatal FC showed a positive correlation with HR during the gratitude intervention, but not during the resentment intervention. Temporostriatal resting-state FC was significantly decreased after the gratitude intervention compared to the resentment intervention. After the gratitude intervention, resting-state FC of the amygdala with the right dorsomedial prefrontal cortex and left dorsal anterior cingulate cortex were positively correlated with anxiety scale and depression scale, respectively. Taken together, our findings shed light on the effect of gratitude meditation on an individual’s mental well-being, and indicate that it may be a means of improving both emotion regulation and self-motivation by modulating resting-state FC in emotion and motivation-related brain regions.