Extraversion modulates functional connectivity hubs of resting‐state brain networks

Personality dimension extraversion describes individual differences in social behaviour and socio‐emotional functioning. The intrinsic functional connectivity patterns of the brain are reportedly associated with extraversion. However, whether or not extraversion is associated with functional hubs warrants clarification. Functional hubs are involved in the rapid integration of neural processing, and their dysfunction contributes to the development of neuropsychiatric disorders. In this study, we employed the functional connectivity density (FCD) method for the first time to distinguish the energy‐efficient hubs associated with extraversion. The resting‐state functional magnetic resonance imaging data of 71 healthy subjects were used in the analysis. Short‐range FCD was positively correlated with extraversion in the left cuneus, revealing a link between the local functional activity of this region and extraversion in risk‐taking. Long‐range FCD was negatively correlated with extraversion in the right superior frontal gyrus and the inferior frontal gyrus. Seed‐based resting‐state functional connectivity (RSFC) analyses revealed that a decreased long‐range FCD in individuals with high extraversion scores showed a low long‐range functional connectivity pattern between the medial and dorsolateral prefrontal cortex, middle temporal gyrus, and anterior cingulate cortex. This result suggests that decreased RSFC patterns are responsible for self‐esteem, self‐evaluation, and inhibitory behaviour system that account for the modulation and shaping of extraversion. Overall, our results emphasize specific brain hubs, and reveal long‐range functional connections in relation to extraversion, thereby providing a neurobiological basis of extraversion.     

Understanding complexity in the human brain

Although the ultimate aim of neuroscientific enquiry is to gain an understanding of the brain and how its workings relate to the mind, the majority of current efforts are largely focused on small questions using increasingly detailed data. However, it might be possible to successfully address the larger question of mind-brain mechanisms if the cumulative findings from these neuroscientific studies are coupled with complementary approaches from physics and philosophy. The brain, we argue, can be understood as a complex system or network, in which mental states emerge from the interaction between multiple physical and functional levels. Achieving further conceptual progress will crucially depend on broad-scale discussions regarding the properties of cognition and the tools that are currently available or must be developed in order to study mind-brain mechanisms.     

Experience-dependent structural plasticity in the adult human brain

Contrary to assumptions that changes in brain networks are possible only during crucial periods of development, research in the past decade has supported the idea of a permanently plastic brain. Novel experience, altered afferent input due to environmental changes and learning new skills are now recognized as modulators of brain function and underlying neuroanatomic circuitry. Given findings in experiments with animals and the recent discovery of increases in gray and white matter in the adult human brain as a result of learning, the old concept of cognitive reserve, that is the ability to reinforce brain volume in crucial areas and thus provide a greater threshold for age-dependent deficits, has been reinforced. The challenge we face is to unravel the exact nature of the dynamic structural alterations and, ultimately, to be able to use this knowledge for disease management. Understanding normative changes in brain structure that occur as a result of environmental changes and demands is pivotal to understanding the characteristic ability of the brain to adapt.     

Multiple conflict-driven control mechanisms in the human brain

Conflict between competing neural representations is thought to serve as an internal signal for the recruitment of 'cognitive control', which resolves conflict by biasing information processing in line with current task demands. Because conflict can occur at different levels of stimulus and response representations, several recent investigations have examined whether conflict-driven cognitive control is domain-general or domain-specific, that is, whether control recruited by one type of conflict affects the resolution of another, but these studies have produced contrary conclusions. I argue here that a critical reading of this literature indicates that the effects of conflict-driven control are domain-specific and are probably mediated by multiple, independent conflict-control loops that can operate in parallel.     

Social cognition and the human brain

Humans are exceedingly social animals, but the neural underpinnings of social cognition and behavior are not well understood. Studies in humans and other primates have pointed to several structures that play a key role in guiding social behaviors: the amygdala, ventromedial frontal cortices, and right somatosensory-related cortex, among others. These structures appear to mediate between perceptual representations of socially relevant stimuli, such as the sight of conspecifics, and retrieval of knowledge (or elicitation of behaviors) that such stimuli can trigger. Current debates concern the extent to which social cognition draws upon processing specialized for social information, and the relative contributions made to social cognition by innate and acquired knowledge.     

Action simulation in the human brain: Twelve questions

Although the idea of action simulation is nowadays popular in cognitive science, neuroscience and robotics, many aspects of the simulative processes remain unclear from empirical, computational, and neural perspectives. In the first part of the article, we provide a critical review and assessment of action simulation theories advanced so far in the wider literature of embodied and motor cognition. We focus our analysis on twelve key questions, and discuss them in the context of human and (occasionally) primate studies. In the second part of the article, we describe an integrative neuro-computational account of action simulation, which links the neural substrate (as revealed in neuroimaging studies of action simulation) to the components of a computational architecture that includes internal modeling, action monitoring and inhibition mechanisms.     

Hemispheric control of hand function in the human brain

The cerebral dominance argument holds that the hand is representative of the functions of the hemisphere by which it is controlled. An influx of visual information to that hemisphere should result in a disruption of simultaneous performance by the hand. This view was tested by requiring the subject to perform a sorting task with one hand whilst at the same time performing a visual task on which information was projected either to the hemisphere relating to hand performance or to its opposite member. Visual information projected to the same hemisphere does not interfere with the performance of the hand. This suggests that control of hand function can be switched from one hemisphere to the other as the need arises.     

Sex differences in human brain size and the general meaning of differences in brain size.

Contrary to commonly held convictions, there is no clear association between brain size and body parameters in humans. Within sexes, once age and health status are controlled for, there is no significant association between brain size and body height for females. For males, body height accounts for no more than .04% of the variance in brain size. The relation between brain weight and body weight is even less clearly defined. Nevertheless, there are large and significant differences in brain size between the sexes. If no adequate body parameters can be found that scale to brain size within the sexes, the marked dimorphism between males and females makes it even more difficult to find a common set of parameters that allow evaluation of brain size differences between sexes. Within and across sexes, there is no convincing link between a limited measure of behavioural capacity (IQ) and brain size. This leads to the more general question: Why would one expect such a link, and, if it is not found, what does this mean in the context of general theories of cortical function?     

Pure correlates of exploration and exploitation in the human brain

Balancing exploration and exploitation is a fundamental problem in reinforcement learning. Previous neuroimaging studies of the exploration–exploitation dilemma could not completely disentangle these two processes, making it difficult to unambiguously identify their neural signatures. We overcome this problem using a task in which subjects can either observe (pure exploration) or bet (pure exploitation). Insula and dorsal anterior cingulate cortex showed significantly greater activity on observe trials compared to bet trials, suggesting that these regions play a role in driving exploration. A model-based analysis of task performance suggested that subjects chose to observe until a critical evidence threshold was reached. We observed a neural signature of this evidence accumulation process in the ventromedial prefrontal cortex. These findings support theories positing an important role for anterior cingulate cortex in exploration, while also providing a new perspective on the roles of insula and ventromedial prefrontal cortex.     

Neural correlates of socioeconomic status in the developing human brain

Socioeconomic disparities in childhood are associated with remarkable differences in cognitive and socio-emotional development during a time when dramatic changes are occurring in the brain. Yet, the neurobiological pathways through which socioeconomic status (SES) shapes development remain poorly understood. Behavioral evidence suggests that language, memory, social-emotional processing, and cognitive control exhibit relatively large differences across SES. Here we investigated whether volumetric differences could be observed across SES in several neural regions that support these skills. In a sample of 60 socioeconomically diverse children, highly significant SES differences in regional brain volume were observed in the hippocampus and the amygdala. In addition, SES × age interactions were observed in the left superior temporal gyrus and left inferior frontal gyrus, suggesting increasing SES differences with age in these regions. These results were not explained by differences in gender, race or IQ. Likely mechanisms include differences in the home linguistic environment and exposure to stress, which may serve as targets for intervention at a time of high neural plasticity.     

主动控制感在大脑表征中的时空标记

主动控制感是主动动作过程中产生的控制自身动作, 进而控制外部环境的主观体验。构成动作主动控制感的核心要素是主观意图与结果反馈。本研究试图通过操控这两个核心要素的不同属性, 借助脑磁图等技术, 探寻主动控制感在大脑额-顶为主的脑网络中前-后馈的作用方式及时空特异性标记, 并建构新的认知神经理论模型。这将有利于理解人类动作的产生及后效、为相关精神类疾病的临床诊断提供更加客观的参照标准。     

人脑自适应多尺度功能连接的性别差异

已有脑成像研究展示了男女脑功能差异, 但功能磁共振信号的频率划分通常基于主观经验, 使脑功能性别差异的生物学解释遭遇瓶颈。本文提出人脑自适应多尺度功能连接算法, 刻画功能连接的时空多尺度特性, 揭示出0.06~0.10 Hz的性别差异：男性较强的连接主要与边缘网络和腹侧注意网络有关, 女性较强的连接主要与腹侧注意网络、视觉网络和额顶网络有关。