Neural correlates underlying insight problem solving: Evidence from EEG alpha oscillations.

Previous studies on insight problem solving using Chinese logogriphs as insight problems only investigated the time- and phase-locked changes of electrocortical responses triggered by Chinese logogriphs, but did not focus on what kind of brain state facilitates individuals to solve insight problems. To investigate this, we focused on participants' alpha activities (8-12 Hz) that closely correlates with insight problem solving and defocused attention while they were solving Chinese logogriphs. Results indicated that in the time window of 800-1400 ms after the presentation of target logogriphs, alpha power over parieto-central electrodes decreased relative to the reference interval in both the successful and unsuccessful logogriphs solving conditions. However, alpha power increased at parieto-occipital electrode sites in successful conditions compared with that in unsuccessful condition. The decrease in alpha activity in both conditions may reflect the cognitive demands in solving the target logogriphs. Furthermore, difference in alpha power between the successful and unsuccessful conditions at parieto-occipital electrode sites is associated with the process of heuristic information. Alpha synchronization observed in the successful condition compared to the unsuccessful condition might reflect a state of defocused attention that facilitates insight problem solving.

Linking inter-individual differences in the conflict adaptation effect to spontaneous brain activity.

Conflict adaptation has been widely researched in normal and clinical populations. There are large individual differences in conflict adaptation, and it has been linked to the schizotypal trait. However, no study to date has examined how individual differences in spontaneous brain activity are related to behavioral conflict adaptation (performance). Resting-state functional magnetic resonance imaging (RS-fMRI) is a promising tool to investigate this issue. The present study evaluated the regional homogeneity (ReHo) of RS-fMRI signals in order to explore the neural basis of individual differences in conflict adaptation across two independent samples comprising a total of 67 normal subjects. A partial correlation analysis was carried out to examine the relationship between ReHo and behavioral conflict adaptation, while controlling for reaction time, standard deviation and flanker interference effects. This analysis was conducted on 39 subjects' data (sample 1); the results showed significant positive correlations in the left dorsolateral prefrontal cortex (DLPFC) and left ventrolateral prefrontal cortex. We then conducted a test-validation procedure on the remaining 28 subjects' data (sample 2) to examine the reliability of the results. Regions of interest were defined based on the correlation results. Regression analysis showed that variability in ReHo values in the DLPFC accounted for 48% of the individual differences in the conflict adaptation effect in sample 2. The present findings provide further support for the importance of the DLPFC in the conflict adaptation process. More importantly, we demonstrated that ReHo of RS-fMRI signals in the DLPFC can predict behavioral performance in conflict adaptation, which provides potential biomarkers for the early detection of cognitive control deterioration.

Regional gray matter volume is associated with rejection sensitivity: a voxel-based morphometry study.

Rejection sensitivity (RS) can be defined as the disposition that one tends to anxiously expect, readily perceive, and intensely react to rejection. High-RS individuals are more likely to suffer mental disorders. Previous studies have investigated brain activity during social rejection using different kinds of rejection paradigms and have provided neural evidence of individual differences in response to rejection cues, but the association between individual differences in RS and brain structure has never been investigated. In this study, voxel-based morphometry (VBM) was used to investigate the relationship between gray matter volume (GMV) and RS in a large healthy sample of 150 men and 188 women. The participants completed the RS Questionnaire and underwent an anatomical magnetic resonance imaging scan. Multiple regression was used to analyze the correlation between regional GMV and RS scores, adjusting for age, sex, and total brain GMV. These results showed that GMV in the region of the posterior cingulate cortex/precuneus was negatively associated with RS, and GMV in the region of the inferior temporal gyrus was positively correlated with RS. These findings suggest a relationship between individual differences in RS and GMV in brain regions that are primarily related to social cognition.

Predictability influences whether outcomes are processed in terms of original or relative values.

Previous studies have provided insights into the representations of original and relative values and the influence of predictability on decision making. However, whether the predictability of outcomes can influence the processing manner of outcomes (i.e. whether the outcomes are processed in terms of original or relative values) is still unknown. To investigate this issue, we had participants perform a monetary decision task which resulted in two outcomes with the same relative values but different original values in either a predictable or unpredictable condition, while recording event-related potentials (ERP). ERP results showed that the outcome processing in the unpredictable condition elicited more positive deflections in the time window of 300-500ms (P300) than did those in the predictable condition. More importantly, the outcome with high original value elicited a greater P300 component than did that with low original value in the unpredictable condition even though these two outcomes had the same relative values, while in the predictable condition no significant difference was observed between ERPs elicited by the two outcomes even though their original values were different. These results suggest that the outcomes might be processed in terms of relative values in the predictable condition but original values in the unpredictable condition.

The correlation between emotional intelligence and gray matter volume in university students.

A number of recent studies have investigated the neurological substrates of emotional intelligence (EI), but none of them have considered the neural correlates of EI that are measured using the Schutte Self-Report Emotional Intelligence Scale (SSREIS). This scale was developed based on the EI model of Salovey and Mayer (1990). In the present study, SSREIS was adopted to estimate EI. Meanwhile, magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) were used to evaluate the gray matter volume (GMV) of 328 university students. Results found positive correlations between Monitor of Emotions and VBM measurements in the insula and orbitofrontal cortex. In addition, Utilization of Emotions was positively correlated with the GMV in the parahippocampal gyrus, but was negatively correlated with the VBM measurements in the fusiform gyrus and middle temporal gyrus. Furthermore, Social Ability had volume correlates in the vermis. These findings indicate that the neural correlates of the EI model, which primarily focuses on the abilities of individuals to appraise and express emotions, can also regulate and utilize emotions to solve problems.

Individuals with high obsessive-compulsive tendencies or undermined confidence rely more on external proxies to access their internal states.

BACKGROUND AND OBJECTIVES: The Seeking Proxies for Internal States (SPIS) hypothesis predicts that obsessive-compulsive disorder (OCD) is associated with a deficit in subjective convictions, which may lead to a reliance on external substitutes for the perceptions of an individual's internal states. Two well-designed studies were performed for the present work that adopted a false bio-feedback procedure in a muscle tension task to examine the SPIS hypothesis. METHODS: The false bio-feedback paradigm was used to investigate our hypothesis. NeXus-10 Mark II hardware and V2011 BioTrace + software (Mind Media B.V., Herten, Netherlands) were utilized to measure the muscle tension of the flexor carpiulnaris muscle, which characterized the target's internal state. In addition, false EMG changes were recorded and displayed on a computer monitor and were considered external proxies. RESULTS: Study 1 demonstrated that the participants with high obsessive-compulsive (OC) tendencies were more affected by the false bio-feedback and exhibited lower confidence in their judgments regarding their muscle tension compared with the participants with low OC tendencies. These findings indicate that subjects with high OC tendencies were more influenced by self-perception effects. In contrast, the subjects in the undermined confidence group in Study 2 were more easily influenced by the false bio-feedback compared with the control group, which suggests that the subjects in the undermined confidence group were more affected by self-perception effects. LIMITATIONS: We did not combine the undermined confidence with OC tendencies or OCD symptoms in our paradigm to investigate their joint effects on self-perception. CONCLUSIONS: Our findings provide further evidence that supports the SPIS hypothesis, which indicates that OC tendencies and the confidence in an individual's recognition of internal states appear to have similar effects on the assessment of internal states and reliance on proxies.

Module number of default mode network: inter-subject variability and effects of sleep deprivation.

Sleep deprivation have shown its great influence on the default mode network (DMN). The DMN is a core system in resting state brain activity. Recent studies have focused on its subsystems and multiple functions. However, the individual specific organization of the DMN is rarely investigated. As the effects of sleep deprivation (SD) on mood are well documented, a more interesting question is whether changes in the processing of emotional information due to sleep deprivation are related to any specific topological properties of the DMN. In this study, we proposed an index, module number of DMN (mnDMN), to measure the specific modular structure of the DMN for each individual. Our results showed that the DMN was generally split into two modules after SD, and the decreased functional connectivity between the two modules was related to a worsening of the participants׳ self-reported emotional state. Furthermore, the mnDMN was correlated with participants' rating scores of high valence pictures in the SD session, indicating that the mnDMN might reflect mood valuation in the human brain. Overall, our research reveals the diversity of the DMN, and may contribute towards a better understanding of the properties and functions of the DMN.

The relationship between latent inhibition and performance at a non-intentional precognition task.

CONTEXT: Many spontaneous cases of extra-sensory perception (ESP) seem to occur without the conscious intent of the experient to manifest any anomalous phenomena. Indeed, Stanford׳s psi-mediated instrumental response (PMIR) theory, which frames ESP as a goal-oriented function, goes as far as to suggest that such intent may be counterproductive to psi. OBJECTIVES: The present study was the latest to build on the successful paradigm developed by Luke and colleagues in testing the non-intentional psi hypothesis and potential covariates of psi task success. This study focused on the ability of latent inhibition-an organism׳s cognitive tendency to filter out apparently irrelevant information-to predict an individual׳s sensitivity to psi stimuli. METHOD: A total of 50 participants completed a two-part auditory discrimination performance measure of latent inhibition; a battery of questionnaires; and a 15-trial, binary, forced-choice, non-intentional precognition task. They were then either positively or negatively rewarded via images from subsets that they had pre-rated, seeing more images from their preferred subsets the better they performed at the psi task and vice versa. RESULTS: Participants scored a mean hit rate of 7.96 [mean chance expectation (MCE) = 7.50], which just failed to reach a statistically significant level, t(48) = 1.62, P = .06, one-tailed, ESr (effect size correlation) = 0.23. However, latent inhibition was found to be unrelated to participants׳ precognitive performance.

Brain structures and functional connectivity associated with individual differences in Internet tendency in healthy young adults.

Internet addiction (IA) incurs significant social and financial costs in the form of physical side-effects, academic and occupational impairment, and serious relationship problems. The majority of previous studies on Internet addiction disorders (IAD) have focused on structural and functional abnormalities, while few studies have simultaneously investigated the structural and functional brain alterations underlying individual differences in IA tendencies measured by questionnaires in a healthy sample. Here we combined structural (regional gray matter volume, rGMV) and functional (resting-state functional connectivity, rsFC) information to explore the neural mechanisms underlying IAT in a large sample of 260 healthy young adults. The results showed that IAT scores were significantly and positively correlated with rGMV in the right dorsolateral prefrontal cortex (DLPFC, one key node of the cognitive control network, CCN), which might reflect reduced functioning of inhibitory control. More interestingly, decreased anticorrelations between the right DLPFC and the medial prefrontal cortex/rostral anterior cingulate cortex (mPFC/rACC, one key node of the default mode network, DMN) were associated with higher IAT scores, which might be associated with reduced efficiency of the CCN and DMN (e.g., diminished cognitive control and self-monitoring). Furthermore, the Stroop interference effect was positively associated with the volume of the DLPFC and with the IA scores, as well as with the connectivity between DLPFC and mPFC, which further indicated that rGMV variations in the DLPFC and decreased anticonnections between the DLPFC and mPFC may reflect addiction-related reduced inhibitory control and cognitive efficiency. These findings suggest the combination of structural and functional information can provide a valuable basis for further understanding of the mechanisms and pathogenesis of IA.

Functional connectivity patterns reflect individual differences in conflict adaptation.

Individuals differ in the ability to utilize previous conflict information to optimize current conflict resolution, which is termed the conflict adaptation effect. Previous studies have linked individual differences in conflict adaptation to distinct brain regions. However, the network-based neural mechanisms subserving the individual differences of the conflict adaptation effect have not been studied. The present study employed a psychophysiological interaction (PPI) analysis with a color-naming Stroop task to examine this issue. The main results were as follows: (1) the anterior cingulate cortex (ACC)-seeded PPI revealed the involvement of the salience network (SN) in conflict adaptation, while the posterior parietal cortex (PPC)-seeded PPI revealed the engagement of the central executive network (CEN). (2) Participants with high conflict adaptation effect showed higher intra-CEN connectivity and lower intra-SN connectivity; while those with low conflict adaptation effect showed higher intra-SN connectivity and lower intra-CEN connectivity. (3) The PPC-centered intra-CEN connectivity positively predicted the conflict adaptation effect; while the ACC-centered intra-SN connectivity had a negative correlation with this effect. In conclusion, our data demonstrated that conflict adaptation is likely supported by the CEN and the SN, providing a new perspective on studying individual differences in conflict adaptation on the basis of large-scale networks.

Disentangling the impacts of outcome valence and outcome frequency on the post-error slowing.

Post-error slowing (PES) reflects efficient outcome monitoring, manifested as slower reaction time after errors. Cognitive control account assumes that PES depends on error information, whereas orienting account posits that it depends on error frequency. This raises the question how the outcome valence and outcome frequency separably influence the generation of PES. To address this issue, we varied the probability of observation errors (50/50 and 20/80, correct/error) the "partner" committed by employing an observation-execution task and investigated the corresponding behavioral and neural effects. On each trial, participants first viewed the outcome of a flanker-run that was supposedly performed by a 'partner', and then performed a flanker-run themselves afterwards. We observed PES in the two error rate conditions. However, electroencephalographic data suggested error-related potentials (oERN and oPe) and rhythmic oscillation associated with attentional process (alpha band) were respectively sensitive to outcome valence and outcome frequency. Importantly, oERN amplitude was positively correlated with PES. Taken together, these findings support the assumption of the cognitive control account, suggesting that outcome valence and outcome frequency are both involved in PES. Moreover, the generation of PES is indexed by oERN, whereas the modulation of PES size could be reflected on the alpha band.

The neural dynamic mechanisms of asymmetric switch costs in a combined Stroop-task-switching paradigm.

Switch costs have been constantly found asymmetrical when switching between two tasks of unequal dominance. We used a combined Stroop-task-switching paradigm and recorded electroencephalographic (EEG) signals to explore the neural mechanism underlying the phenomenon of asymmetrical switch costs. The results revealed that a fronto-central N2 component demonstrated greater negativity in word switch (cW) trials relative to word repeat (wW) trials, and both First P3 and P3b components over the parieto-central region exhibited greater positivity in color switch (wC) trials relative to color repeat (cC) trials, whereas a contrasting switch-related fronto-central SP effect was found to have an opposite pattern for each task. Moreover, the time-frequency analysis showed a right-frontal lower alpha band (9-11 Hz) modulation in the word task, whereas a fronto-central upper alpha band (11-13 Hz) modulation was exclusively found in the color task. These results provide evidence for dissociable neural processes, which are related to inhibitory control and endogenous control, contributing to the generation of asymmetrical switch costs.

Priming with threatening faces modulates the self-face advantage by enhancing the other-face processing rather than suppressing the self-face processing.

Social emotional information influences self-processing in everyday activities, but few researchers have investigated this process. The current ERP study adopted a prime paradigm to investigate how socially threatening faces impact on the self-face processing advantage. After being primed with emotional faces (happy, angry or neutral), participants judged whether the target face (self, friend, and stranger) was familiar or unfamiliar. Results showed an interaction effect between the prime face and the target face at posterior P3, suggesting that after priming with happy and neutral faces, self-faces elicited larger P3 amplitudes than friend-faces and stranger-faces; however, after priming with angry faces, the P3 amplitudes were not significantly different between self-face and friend-face. Moreover, the P3 amplitudes of self-faces did not differ between priming with angry and neutral faces; however, the P3 amplitude of both friend-faces and stranger-faces showed enhanced responses after priming with angry faces compared to priming with neutral faces. We suggest that the self-face processing advantage (self vs. friend) could be weakened by priming with threatening faces, through enhancement of the other-faces processing rather than suppression of self-faces processing in angry vs. neutral face prime.

Association between regional white and gray matter volume and ambiguity tolerance: Evidence from voxel-based morphometry.

The concept of tolerance of ambiguity (AT) is defined as the way in which an individual tends to perceive and deal with confusing, vague, and unclear situations. AT is generally considered as an important personality trait, but the neural mechanisms underlying individual differences in AT have never been investigated. Using voxel-based morphometry and MSTAT-II scale, we investigated the correlations between AT and regional white matter volume (rWMV) and regional gray matter volume (rGMV) in 351 young healthy subjects. We found AT to be positively correlated with rGMV in the dorsolateral prefrontal cortex (DLPFC), and negatively correlated with rGMV in the precuneus. These results indicate that increased rGMV in the left DLPFC may lead to characteristics of ambiguous stimuli consideration from multiple contexts and risk taking. Decreased rGMV in the left precuneus may be associated with a high tolerance for ambiguity, which attributes uncertainty to self-related factors.

Predicting stroop effect from spontaneous neuronal activity: a study of regional homogeneity.

The Stroop effect is one of the most robust and well-studied phenomena in cognitive psychology and cognitive neuroscience. However, little is known about the relationship between intrinsic brain activity and the individual differences of this effect. In the present study, we explored this issue by examining whether resting-state functional magnetic resonance imaging (rs-fMRI) signals could predict individual differences in the Stroop effect of healthy individuals. A partial correlation analysis was calculated to examine the relationship between regional homogeneity (ReHo) and Stroop effect size, while controlling for age, sex, and framewise displacement (FD). The results showed positive correlations in the left inferior frontal gyrus (LIFG), the left insula, the ventral anterior cingulate cortex (vACC), and the medial frontal gyrus (MFG), and negative correlation in the left precentral gyrus (LPG). These results indicate the possible influences of the LIFG, the left insula, and the LPG on the efficiency of cognitive control, and demonstrate that the key nodes of default mode network (DMN) may be important in goal-directed behavior and/or mental effort during cognitive control tasks.

Regional gray matter volume and anxiety-related traits interact to predict somatic complaints in a non-clinical sample.

Somatic complaints can be important features of an individual's expression of anxiety. Anxiety-related traits are also risk factors for somatic symptoms. However, it is not known which neuroanatomical mechanisms may be responsible for this relationship. In this study, our first step was to use voxel-based morphometry (VBM) approaches to investigate the neuroanatomical basis underlying somatic complaints in a large sample of healthy subjects. We found a significant positive correlation between somatic complaints and parahippocampal gyrus (PHG) volume adjacent to the entorhinal cortex. Further analysis revealed that the interaction between PHG volume/entorhinal cortex and neuroticism-anxiety (N-Anx) predicted somatic complaints. Specifically, somatic complaints were associated with higher N-Anx for individuals with increased PHG volume. These findings suggest that increased PHG volume and higher trait anxiety can predict vulnerability to somatic complaints in the general population.

When you smile, you become happy: evidence from resting state task-based fMRI.

Simulation studies on emotion have shown that facial actions can initiate and modulate particular emotions. However, the neural mechanisms of these initiating and modulating functions are unclear. In this study, we used resting-state functional magnetic resonance imaging (fMRI) and task-based fMRI to explore these processes by examining spontaneous cerebral activities and brain activations under two conditions: holding a pen using only the teeth (HPT: facilitating the muscles typically associated with smiling) and holding a pen using only the lips (HPL: inhibiting the muscles typically associated with smiling). The resting-state fMRI results showed that compared with the HPL condition, significant increases in the amplitudes of low-frequency fluctuations were found in the right posterior cingulate gyrus [PCG; Brodmann area 31 (BA31)] and in the left middle frontal gyrus (MFG; BA9) in the HPT condition. These findings might be related to the initiation of positive emotions (PCG) and to the control and allocation of attention (MFG). The task-based fMRI results showed that the inferior parietal lobule, left supplementary motor area, superior parietal lobule, precuneus, and bilateral middle cingulum were active when facial manipulation influenced the recognition of emotional facial expressions. These results demonstrate that facial actions might not only initiate a particular emotion and draw attention, but also influence face-based emotion recognition.

Identifying the core components of emotional intelligence: evidence from amplitude of low-frequency fluctuations during resting state.

Emotional intelligence (EI) is a multi-faceted construct consisting of our ability to perceive, monitor, regulate and use emotions. Despite much attention being paid to the neural substrates of EI, little is known of the spontaneous brain activity associated with EI during resting state. We used resting-state fMRI to investigate the association between the amplitude of low-frequency fluctuations (ALFFs) and EI in a large sample of young, healthy adults. We found that EI was significantly associated with ALFFs in key nodes of two networks: the social emotional processing network (the fusiform gyrus, right superior orbital frontal gyrus, left inferior frontal gyrus and left inferior parietal lobule) and the cognitive control network (the bilateral pre-SMA, cerebellum and right precuneus). These findings suggest that the neural correlates of EI involve several brain regions in two crucial networks, which reflect the core components of EI: emotion perception and emotional control.

Reduced representations capacity in visual working memory in trait anxiety.

Neural processes that support individual differences in trait anxiety and the amount of representations in visual-spatial working memory (WM) are currently unclear. We measured the contralateral delay activity (CDA) in a lateralized change detection task to explore this question. Different levels of memory load were varied within each block. Despite their unimpaired behavioral performance, individuals with high traitanxious(HTA) displayed several changes in the neuronal markers of the memory processes. The CDA amplitudes reached asymptote at loads of three and four items for HTA and low traitanxious(LTA) individuals, respectively. This result indicates that HTA individuals reach the upper limit of representation capacity with a smaller memory load than LTA individuals. Furthermore, the smaller CDA amplitudes in HTA individuals under high memory loads could be attributed to less contralateral cortical activity, which further indicates that HTA individuals are associated with reduced representations of taskrelevantitems in WM.

Females and males rely on different cortical regions in Raven's Matrices reasoning capacity: evidence from a voxel-based morphometry study.

Raven's Matrices test (RMT) is a non-verbal test designed to assess individuals' ability to reason and solve new problems without relying extensively on declarative knowledge derived from schooling or previous experience. Despite a large number of behavioral studies that demonstrated gender differences in Raven's Matrices reasoning ability, no neural evidence supported this difference. In this study, voxel-based morphometry (VBM) was used in an attempt to uncover the gender-specific neural basis of Raven's Matrices reasoning ability as measured by the combined Raven's Matrices test (CRT) in 370 healthy young adults. The behavioral results showed no difference between males and females. However, the VBM results showed that the relationship between reasoning ability and regional gray matter volume (rGMV) differed between sexes. The association between CRT scores and rGMV in the dorsolateral prefrontal cortex (associated with visuospatial ability) was significantly greater in males than in females, whereas the reverse was true for the inferior frontal cortex (relating to verbal reasoning ability) and the medial frontal cortex (engaged in information binding) where the association was greater in females. These findings suggest that males and females use differently structured brains in different ways to achieve similar levels of overall Raven's Matrices reasoning ability.