Wavelet-based coherence between large-scale resting-state networks : neurodynamics marker for autism?

Neurodynamics is poorly understood and has raised interest of neuroscientists over the past decade. When a brain pathology cannot be described through structural or functional brain analyses, neurodynamics based descriptors might be the only option to understand a pathology and maybe predict its symptomatic evolution. For example, adolescents or adults with autism have shown mixed results when their intrinsic structural and functional connectivity parameters in the brain at rest were assessed. To visualize neurodynamics parameters we use wavelet coherence maps, which show when and at which frequency two large-scale resting-state networks (RSNs) co-vary and display phase-locked behavior. Here the wavelet-based coherence coefficients are extracted from fMRI of adolescents with and without autism. More specifically, we introduce a novel metric: ‘time of in- phase coherence’ between pairs of resting-state networks. Results show that wavelet coherence maps can be used as neurodynamics maps, and that features such as ‘time of in-phase coherence’ can be calculated between pairs of resting-state networks. This wavelet-based metric shows actually weaker coherent patterns between the ventral stream and the executive control network in patient with autism.

Social behaviour and social cognition in high-functioning adolescents with autism spectrum disorder (ASD): two sides of the same coin?

Contains fulltext : 195873.pdf (publisher's version ) (Open Access)Of the triad of symptoms found in autism spectrum disorder (ASD), that is, social impairments, communication difficulties and repetitive interests and behaviour, the social impairments are the most stable and common throughout the lifespan. They typically manifest themselves in abnormalities as reciprocal interactions and difficulties in the expression and recognition of emotions. Although peer interactions become especially important during adolescence, little is known about the mentalizing abilities of high-functioning adolescents with ASD. Here, we compared the mentalizing skills and emotion recognition abilities of 21 high-functioning adolescents with ASD and 21 matched controls. All adolescents had estimated above-average verbal intelligence levels. Spontaneous social abilities and task-related social abilities were measured using questionnaires, tasks and the Autism Diagnostic Observation Schedule. Results confirm social impairment in daily life situations in adolescents with ASD, but were not found on experimental tasks of social cognition. The use of more explicit cognitive or verbally mediating reasoning techniques and a lesser tendency of high-functioning adolescents with ASD to search for and use social information in natural environments are further discussed.11 p

Transanal Employment of Single Access Ports Is Feasible for Rectal Surgery

Objective: To evaluate the feasibility of transanal single port surgery in 15 consecutive patients. Background: The current method of choice for local resection of rectal tumors is transanal endoscopic microsurgery (TEM), a complex and expensive technique. Single access surgery is easy, relatively cheap, and more broadly applied in laparoscopy. Evidence regarding transanal use of single access ports is scarce. Methods: Consecutive patients with a rectal lesion otherwise eligible for TEM were operated using the Single Site Laparoscopic Access System (SSL) and standard laparoscopic instrumentation. Patient, lesion and procedure characteristics, hospitalization length, and peroperative and postoperative complications were recorded. Results: Fifteen patients were planned for single port transanal surgery. In 2 patients (13.3%), intrarectal retractor expansion failed, and conversion to conventional TEM was necessary. The remaining 13 patients were successfully operated. Rectal lesions (mean diameter 36 mm, standard deviation +/- 25 mm, mean distance from the dentate line 6 cm [+/- 4.5]) included adenoma in 7 patients, T1 adenocarcinoma in 1, T2 adenocarcinoma in 3, carcinoid in 1, and fibrosis only in 1 (after prior polypectomy). All patients were operated in lithotomy position. Resections were en bloc, full thickness, and had complete margins. Resection specimens measured 65 (+/- 35) x 52 (+/- 24) mm. Twelve rectal defects were sutured. One peroperative pneumoscrotum occurred. Mean operating time was 57 (+/- 39) minutes. One patient presented with postoperative hemorrhage, treated conservatively (postoperative morbidity rate 7.7%). Mean hospitalization lasted 2.5 days (+/- 2.7). Conclusions: Transanal single port surgery via the SSL is feasible and safe and may become a promising alternative to TE

Working memory network alterations in high-functioning adolescents with an autism spectrum disorder

\u3cp\u3eAim: People with autism spectrum disorder (ASD) typically have deficits in the working memory (WM) system. WM is found to be an essential chain in successfully navigating in the social world. We hypothesize that brain networks for WM have an altered network integrity in ASD compared to controls. Methods: Thirteen adolescents (one female) with autistic disorder (n = 1), Asperger's disorder (n = 7), or pervasive developmental disorder not otherwise specified (n = 5), and 13 typically developing healthy control adolescents (one female) participated in this study. Functional magnetic resonance imaging (MRI) was performed using an n-back task and in resting state. Results: The analysis of the behavioral data revealed deficits in WM performance in ASD, but only when tested to the limit. Adolescents with ASD showed lower binary global efficiency in the WM network than the healthy control group with n-back and resting-state data. This correlated with diagnostic scores for total problems, reciprocity, and language. Conclusion: Adolescents with higher-functioning autism have difficulty with the WM system, which is typically compensated. Functional MRI markers of brain network organization in ASD are related to characteristics of autism as represented in diagnostic scores. Therefore, functional MRI provides neuronal correlates for memory difficulties in adolescents with ASD.\u3c/p\u3

Colorectal surgeons' learning curve of transanal endoscopic microsurgery

Transanal endoscopic microsurgery (TEM) is a technically demanding key technique in minimally invasive rectal surgery. We investigated the learning curve of colorectal surgeons commencing with TEM. All TEM procedures of four colorectal surgeons were analyzed. Procedures were ranked chronologically per surgeon. Outcomes included conversion, postoperative complications, procedure time, and recurrence. Backward multivariable regression analysis identified learning curve effects and other predictors. Four surgeons resected 693 rectal lesions [69.9 % adenoma/25.5 % carcinoma; median size 20 cm(2); interquartile range (IQR) 11-35; 7 ± 4 cm ab ano]. A total of 555 resections (80.1 %) were histopathologically radical (R0). Conversion (4.3 %) was influenced by a learning curve [odds ratio (OR) 0.991 per additional procedure; 95 % confidence interval (CI) 0.984-0.998] and by lesion size. Postoperative complications depended only on the individual surgeon and lesion size in benign lesions (10.4 % complications). A learning curve (OR 0.99; 95 % CI 0.988-0.998) and peritoneal entrance affected complications in malignant lesions (13.3 %). Procedure time [median 55 min (IQR 30-90)] was influenced by a learning curve [B -0.11 (95 % CI -0.14 to -0.09)], individual surgeon, single-piece resection, peritoneal entrance, lesion size, and rectal quadrant. Recurrence of benign lesions (4.5 %) depended on lesion size, R0 resection, and prior resection attempts. Recurrence of malignant lesions (8.9 %) depended on 3D stereoscopic view, lesion size, full-thickness resection, and length of follow-up. Recurrence-free survival of patients operated during the 36th through 80th procedure per surgeon was significantly shorter than in patients operated during procedures 1-35 and 81 onwards. A surgical learning curve affected conversion rate, procedure time, and complication rate. It did not influence recurrence rates, possibly due to evolving patient populations. This first insight into the learning curve of TEM stresses the importance of quality monitoring and centralisation of car

Brain resting-state networks in adolescents with high-functioning autism: Analysis of spatial connectivity and temporal neurodynamics

Introduction Autism spectrum disorder (ASD) is mainly characterized by functional and communication impairments as well as restrictive and repetitive behavior. The leading hypothesis for the neural basis of autism postulates globally abnormal brain connectivity, which can be assessed using functional magnetic resonance imaging (fMRI). Even in the absence of a task, the brain exhibits a high degree of functional connectivity, known as intrinsic, or resting-state, connectivity. Global default connectivity in individuals with autism versus controls is not well characterized, especially for a high-functioning young population. The aim of this study is to test whether high-functioning adolescents with ASD (HFA) have an abnormal resting-state functional connectivity. Materials and Methods We performed spatial and temporal analyses on resting-state networks (RSNs) in 13 HFA adolescents and 13 IQ- and age-matched controls. For the spatial analysis, we used probabilistic independent component analysis (ICA) and a permutation statistical method to reveal the RSN differences between the groups. For the temporal analysis, we applied Granger causality to find differences in temporal neurodynamics. Results Controls and HFA display very similar patterns and strengths of resting-state connectivity. We do not find any significant differences between HFA adolescents and controls in the spatial resting-state connectivity. However, in the temporal dynamics of this connectivity, we did find differences in the causal effect properties of RSNs originating in temporal and prefrontal cortices. Conclusion The results show a difference between HFA and controls in the temporal neurodynamics from the ventral attention network to the salience-executive network: a pathway involving cognitive, executive, and emotion-related cortices. We hypothesized that this weaker dynamic pathway is due to a subtle trigger challenging the cognitive state prior to the resting state