Institute of Psychology,Chinese Academy Of Sciences
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Changes in structural and functional connectivity among resting-state networks across the human lifespan
No full textAt rest, the brain's sensorimotor and higher cognitive systems engage in organized patterns of correlated activity forming resting-state networks. An important empirical question is how functional connectivity and structural connectivity within and between resting-state networks change with age. In this study we use network modeling techniques to identify significant changes in network organization across the human lifespan. The results of this study demonstrate that whole-brain functional and structural connectivity both exhibit reorganization with age. On average, functional connections within resting-state networks weaken in magnitude while connections between resting-state networks tend to increase. These changes can be localized to a small subset of functional connections that exhibit systematic changes across the lifespan. Collectively, changes in functional connectivity are also manifest at a system-wide level, as components of the control, default mode, saliency/ventral attention, dorsal attention, and visual networks become less functionally cohesive, as evidenced by decreased component modularity. Paralleling this functional reorganization is a decrease in the density and weight of anatomical white-matter connections. Hub regions are particularly affected by these changes, and the capacity of those regions to communicate with other regions exhibits a lifelong pattern of decline. Finally, the relationship between functional connectivity and structural connectivity also appears to change with age; functional connectivity along multi-step structural paths tends to be stronger in older subjects than in younger subjects. Overall, our analysis points to age-related changes in inter-regional communication unfolding within and between resting-state networks. (c) 2014 Elsevier Inc. All rights reserved
Linking brain electrical signals elicited by current outcomes with future risk decision-making
No full textThe experience of current outcomes influences future decisions in various ways. The neural mechanism of this phenomenon may help to clarify the determinants of decision-making. In this study, thirty-nine young adults finished a risky gambling task by choosing between a high- and a low-risk option in each trial during electroencephalographic data collection. We found that risk-taking strategies significantly modulated mean amplitudes of the event-related potential (ERP) component P3, particularly at the central scalp. The event-related spectral perturbation and the inter-trial coherence measurements of the independent component analysis (ICA) data indicated that the "stay" vs. "switch" electrophysiological difference associated with subsequent decision-making was mainly due to fronto-central theta and left/right mu independent components. Event-related cross-coherence results suggested that the neural information of action monitoring and updating emerged in the fronto-central cortex and propagated to sensorimotor area for further behavior adjustment. Based on these findings of ERP and event-related oscillation (ERO) measures, we propose a neural model of the influence of current outcomes on future decisions
Voluntary Pressing and Releasing Actions Induce Different Senses of Time: Evidence from Event-Related Brain Responses
No full textThe timing intervals initiated by voluntary pressing actions are subjectively compressed compared with those initiated by voluntary releasing actions. Event-related potentials (ERPs) were employed in the present study to uncover the temporal mechanisms underlying this temporal illusion. The results revealed that the mean amplitude of the P1 component over the frontal-central recording sites, but not the P2 component, was larger in the voluntary pressing condition than in the voluntary releasing condition at the time perception stage. In the fronto-central region, increases in oscillatory activities of delta-theta frequency range (1-7 Hz) were found in the voluntary pressing condition, which corresponded with the emergence of the P1 peak. In addition, the P1 amplitude was negatively related to the corresponding reported time length at the single-trial level. These results are discussed in terms of the functional role of the response-locked P1 in the time perception stage
The Relation between Thematic Role Computing and Semantic Relatedness Processing during On-Line Sentence Comprehension
No full textSentence comprehension involves timely computing different types of relations between its verbs and noun arguments, such as morphosyntactic, semantic, and thematic relations. Here, we used EEG technique to investigate the potential differences in thematic role computing and lexical-sematic relatedness processing during on-line sentence comprehension , and the intraction between these two types of processes. Mandarin Chinese sentences were used as materials. The basic structure of those sentences is "Noun+Verb+'le'+a two-character word", with the Noun being the initial argument. The verb disambiguates the initial argument as an agent or a patient, Meanwhile, the initial argument and the verb are highly or lowly semantically related. The ERPs at the verbs revealed that: relative to the agent condition, the patient condition evoked a larger N400 only when the argument and verb were lowly semantically related; however, relative to the high-relatedness condition, the low-relatedness condition elicited a larger N400 regardless of the thematic relation; although both thematic role variation and sematic relatedness variation elicited N400 effects, the N400 effect elicited by the former was broadly distributed and reached maximun over the frontal electrodes, and the N400 effect elicited by the latter had a posterior distribution. In addition, the brain oscillations results showed that, although thematic role variation (patient vs. agent) induced power decreases around the beta frequency band (15-30 Hz), semantic relatedness variation (low-relatedness vs. high-relatedness) induced power increases in the theta frequency band (4-7 Hz). These results suggested that, in the sentence context, thematic role computing is modulated by the sematic relatedness between the verb and its argument; semantic relatedness processing, however, is in some degree independent from the thematic relations. Moreover, our results indicated that, during on-line sentence comprehension, thematic role computing and sematic relatedness processing are mediated by distinct neural systems
White matter abnormalities in medication-naive adult patients with major depressive disorder: Tract-based spatial statistical analysis
No full textOBJECTIVE: While increasing evidence suggests that major depressive disorder (MDD) is coincident with the altered white matter microstructure in many brain regions including the prefrontal cortex, parietal lobe, ventral tegmental area and limbic system, it remains controversial in the nature of white matter structural changes and in its relationship with depression syndrome. We believe that the age of patients and the antidepressant treatment to them would contribute to that controversy. Here in this study we explored the microstructural changes of the entire brain white matter of the adult patients with first-episode, antidepressant drug-naive MDD
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