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Brain connectivity analyses have been widely performed to investigate the organization and functioning of the brain, or to observe changes in neurological or psychiatric conditions. However, connectivity analysis inevitably introduces the problem of mass-univariate hypothesis testing. Although, several cluster-wise correction methods have been suggested to address this problem and shown to provide high sensitivity, these approaches fundamentally have two drawbacks: the lack of spatial specificity (localization power) and the arbitrariness of an initial cluster-forming threshold. In this study, we propose a novel method, degree-based statistic (DBS), performing cluster-wise inference. DBS is designed to overcome the above-mentioned two shortcomings. From a network perspective, a few brain regions are of critical importance and considered to play pivotal roles in network integration. Regarding this notion, DBS defines a cluster as a set of edges of which one ending node is shared. This definition enables the efficient detection of clusters and their center nodes. Furthermore, a new measure of a cluster, center persistency (CP) was introduced. The efficiency of DBS with a known 'ground truth' simulation was demonstrated. Then they applied DBS to two experimental datasets and showed that DBS successfully detects the persistent clusters. In conclusion, by adopting a graph theoretical concept of degrees and borrowing the concept of persistence from algebraic topology, DBS could sensitively identify clusters with centric nodes that would play pivotal roles in an effect of interest. DBS is potentially widely applicable to variable cognitive or clinical situations and allows us to obtain statistically reliable and easily interpretable results. Hum Brain Mapp 38:165-181, 2017. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objective: We sought to study patterns of imaging for follow-up after surgery for stage T1 renal cell carcinoma (RCC) at a single institution. We hypothesised that there would be significant variation in the use of surveillance imaging. Methods and materials: We evaluated the two-year follow-up of 317 consecutive patients undergoing radical or partial nephrectomy who were found to have pT1 RCC. Follow-up imaging data were collected. Surgical characteristics and tumour pathology data were analysed via a Poisson regression model to evaluate the incidence rate ratio for frequency of imaging based on each variable. Logistic regression was used to evaluate factors correlated with concordance with current imaging guidelines. Results: A total of 1016 imaging exams were performed after surgery on 268 patients. These studies identified four tumour recurrences: two local and two lung. The overall recurrence rate was 1.49%. Three recurrences were found within a two-year postoperative window, and one was recorded on the patient’s last clinic note after two years. Of 66 imaging exams with findings suspicious for recurrence, 62 were found to be false positives. All statistical analyses on a subgroup of 162 patients with full two-year follow-up failed to demonstrate any correlation between clinicopathologic variables and the frequency of abdominal imaging or concordance with current imaging guidelines. Conclusions: Frequent follow-up imaging studies were obtained despite a low recurrence rate. There was a high rate of false-positive findings on routine exams. No clinicopathologic criteria were identified that were correlated with increased imaging frequency. [ABSTRACT FROM AUTHOR]

Intrinsic functional connectivity from resting state functional magnetic resonance imaging (rsfMRI) has increasingly received attention as a possible predictor of cognitive function and performance. In this study, we investigated the influence of practicing skillful tool manipulation on intrinsic functional connectivity in the resting brain. Acquisition of tool-use skill has two aspects such as formation of motor representation for skillful manipulation and acquisition of the tool concept. To dissociate these two processes, we chose chopsticks-handling with the non-dominant hand. Because participants were already adept at chopsticks-handling with their dominant hand, practice with the non-dominant hand involved only acquiring the skill for tool manipulation with existing knowledge. Eight young participants practiced chopsticks-handling with their non-dominant hand for 8 weeks. They underwent functional magnetic resonance imaging (fMRI) sessions before and after the practice. As a result, functional connectivity among tool-use-related regions of the brain decreased after practice. We found decreased functional connectivity centered on parietal areas, mainly the supramarginal gyrus (SMG) and superior parietal lobule (SPL) and additionally between the primary sensorimotor area and cerebellum. These results suggest that the parietal lobe and cerebellum purely mediate motor learning for skillful tool-use. This decreased functional connectivity may represent increased efficiency of functional network [ABSTRACT FROM AUTHOR]