Simon argued that near-decomposability was a virtually universal property of complex systems because it conferred a very important evolutionary or adaptive advantage. In mainstream contemporary parlance, Simon’s near-decomposability is closely analogous to the concept of topological modularity: nodes in the same module have dense intra-modular connectivity with each other and sparse inter-modular connectivity with nodes in other modules ( Newman, 2004 systems where elements have most of their interactions (of any kind) with a subset of elements in some sense close to them, and much less interaction with elements outside this subset. He introduced the notion of “nearly-decomposable systems”, i.e. In this prescient analysis, he argued that most complex systems, such as social, biological and physical symbolic systems, are organized in a hierarchical manner. This could enable future investigations of Simon’s original hypothesis that hierarchy or near-decomposability of physical symbol systems is a critical design feature for their fast adaptivity to changing environmental conditions.Īlmost 50 years ago, Herbert Simon wrote an essay entitled “The architecture of complexity” ( Simon, 1962 We conclude that methods are available for hierarchical modular decomposition of large numbers of high resolution brain functional networks using computationally expedient algorithms. Connector nodes and hubs, with a key role in inter-modular connectivity, were also concentrated in association cortical areas. The largest five modules at the highest level of the hierarchy were medial occipital, lateral occipital, central, parieto-frontal and fronto-temporal systems occipital modules demonstrated less sub-modular organization than modules comprising regions of multimodal association cortex. Results show that human brain functional networks have a hierarchical modular organization with a fair degree of similarity between subjects, I = 0.63. We used mutual information, 0 < I < 1, to estimate the similarity of community structure of networks in different subjects, and to identify the individual network that is most representative of the group. We used a customized template to extract networks with more than 1800 regional nodes, and we applied a fast algorithm to identify nested modular structure at several hierarchical levels. Here we investigate the hierarchical modular (or “modules-within-modules”) decomposition of human brain functional networks, measured using functional magnetic resonance imaging in 18 healthy volunteers under no-task or resting conditions. We hypothesize that acupuncture may mediate its antipain, antianxiety, and other therapeutic effects via this intrinsic neural circuit that plays a central role in the affective and cognitive dimensions of pain as well as in the regulation and integration of emotion, memory processing, autonomic, endocrine, immunological, and sensorimotor functions.The idea that complex systems have a hierarchical modular organization originated in the early 1960s and has recently attracted fresh support from quantitative studies of large scale, real-life networks. Our results provide additional evidence in support of previous reports that acupuncture modulates the limbic-paralimbic-neocortical network. The sensorimotor cortices (somatosensory cortices, supplementary motor cortex), thalamus and occasional paralimbic structures such as the insula and anterior middle cingulate cortex showed activation. Clusters of deactivated regions were seen in the medial prefrontal cortex (frontal pole, pregenual cingulate), the temporal lobe (amygdala, hippocampus, and parahippocampus) and the posterior medial cortex (precuneus, posterior cingulate). Acupuncture produced extensive deactivation of the limbic-paralimbic-neocortical system. Although certain differences could be observed between real and sham points, the hemodynamic response (BOLD signal changes) and psychophysical response (sensory experience) to acupuncture were generally similar for all four points.
2009 HUMAN BRAIN MAPPING MANUAL
To test if this finding applies to other major classical acupoints, fMRI was performed on 10 healthy adults during manual acupuncture at Taichong (LV3), Xingjian (LV2), Neiting (ST44), and a sham point on the dorsum of the left foot. fMRI studies at Hegu (LI4) and Zusanli (ST36) indicated that the limbic system may play an important role for acupuncture effects. However, the neural substrates of acupuncture actions are not completely clear to date. Human and animal studies suggest that acupuncture produces many beneficial effects through the central nervous system.
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