Alterations of cerebral perfusion and functional brain connectivity in medication-naïve male adults with attention-deficit/hyperactivity disorder.

AIMS: Functional brain abnormalities, including altered cerebral perfusion and functional connectivities, have been illustrated in adults with attention-deficit/hyperactivity disorder (aADHD). The present study attempted to explore the alterations of cerebral blood flow (CBF) and resting-state functional connectivity (RSFC) simultaneously to understand the neural mechanisms for adults with ADHD comprehensively. METHODS: Resting-state arterial spin labeling (ASL) and blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) data were acquired for 69 male aADHD and 69 matched healthy controls (HCs). The altered CBFs associated with aADHD were explored based on both categorical (aADHD vs HCs) and dimensional (correlation with aADHD core symptoms) perspectives. Then, the seed-based RSFC analyses were developed for the regions showing significant alterations of CBF. RESULTS: Significantly decreased CBF in the large-scale resting-state networks regions (eg, ventral attentional network, somatomotor network, limbic network) and subcortical regions was indicated in aADHD compared with HCs. The correlation analyses indicated that the hypoperfusion in left putamen/global pallidum and left amygdala/hippocampus was correlated with ADHD inattentive and total symptoms, respectively. Further, weaker negative functional connectivity between left amygdala and bilateral supplementary motor area, bilateral superior frontal gyrus, and left medial frontal gyrus was found in adults with ADHD. CONCLUSION: The present findings suggested alterations of both cerebral perfusion and functional connectivity for the left amygdala in aADHD. The combination of CBF and RSFCs may help to interpret the neuropathogenesis of ADHD more comprehensively.

A shared effect of paroxetine treatment on gray matter volume in depressive patients with and without childhood maltreatment: A voxel-based morphometry study.

AIMS: This study assessed whether antidepressant drug treatment has a common effect on gray matter (GM) volume in MDD patients with and without childhood maltreatment (CM). METHODS: T1-weighted structural magnetic resonance imaging data were collected from 168 participants, including 51 MDD patients with CM, 31 MDD patients without CM, 48 normal controls with CM, and 38 normal controls without CM. MDD patients received 6 months of treatment with paroxetine, and 24 patients with CM, and 16 patients without CM received a second MRI scan. A whole-brain voxel-based morphometry approach was used to estimate GM volume in each participant at two time points. Two-way analysis of variance (ANOVA) was used to determine the effects of MDD and CM on GM volume at baseline. Repeated measures two-way ANOVA was used to determine the treatment-by-CM interactive effect and main effect of treatment during paroxetine treatment. We further investigated the relationship between GM volume and clinical variables. RESULTS: At baseline, significant MDD-by-CM interactive effects on GM volume were mainly observed in the left parahippocampal gyrus, left entorhinal cortex, and left cuneus. GM volume was significantly lower mainly in the right middle temporal gyrus in patients with MDD than in normal controls. We did not find any significant treatment-by-CM interactive effects. However, a treatment-related increase in GM was found in the right middle temporal gyrus in both MDD groups. CONCLUSIONS: These results suggest that paroxetine treatment operates via a shared neurobiological mechanism in MDD patients with and without CM.

Test-retest reliability of graph metrics in high-resolution functional connectomics: a resting-state functional MRI study.

BACKGROUND: The combination of resting-state functional MRI (R-fMRI) technique and graph theoretical approaches has emerged as a promising tool for characterizing the topological organization of brain networks, that is, functional connectomics. In particular, the construction and analysis of high-resolution brain connectomics at a voxel scale are important because they do not require prior regional parcellations and provide finer spatial information about brain connectivity. However, the test-retest reliability of voxel-based functional connectomics remains largely unclear. AIMS: This study tended to investigate both short-term (∼20 min apart) and long-term (6 weeks apart) test-retest (TRT) reliability of graph metrics of voxel-based brain networks. METHODS: Based on graph theoretical approaches, we analyzed R-fMRI data from 53 young healthy adults who completed two scanning sessions (session 1 included two scans 20 min apart; session 2 included one scan that was performed after an interval of ∼6 weeks). RESULTS: The high-resolution networks exhibited prominent small-world and modular properties and included functional hubs mainly located at the default-mode, salience, and executive control systems. Further analysis revealed that test-retest reliabilities of network metrics were sensitive to the scanning orders and intervals, with fair to excellent long-term reliability between Scan 1 and Scan 3 and lower reliability involving Scan 2. In the long-term case (Scan 1 and Scan 3), most network metrics were generally test-retest reliable, with the highest reliability in global metrics in the clustering coefficient and in the nodal metrics in nodal degree and efficiency. CONCLUSION: We showed high test-retest reliability for graph properties in the high-resolution functional connectomics, which provides important guidance for choosing reliable network metrics and analysis strategies in future studies.

Functional brain hubs and their test-retest reliability: a multiband resting-state functional MRI study.

Resting-state functional MRI (R-fMRI) has emerged as a promising neuroimaging technique used to identify global hubs of the human brain functional connectome. However, most R-fMRI studies on functional hubs mainly utilize traditional R-fMRI data with relatively low sampling rates (e.g., repetition time [TR]=2 s). R-fMRI data scanned with higher sampling rates are important for the characterization of reliable functional connectomes because they can provide temporally complementary information about functional integration among brain regions and simultaneously reduce the effects of high frequency physiological noise. Here, we employed a publicly available multiband R-fMRI dataset with a sub-second sampling rate (TR=645 ms) to identify global hubs in the human voxel-wise functional networks, and further examined their test-retest (TRT) reliability over scanning time. We showed that the functional hubs of human brain networks were mainly located at the default-mode regions (e.g., medial prefrontal and parietal cortex as well as the lateral parietal and temporal cortex) and the sensorimotor and visual cortex. These hub regions were highly anatomically distance-dependent, where short-range and long-range hubs were primarily located at the primary cortex and the multimodal association cortex, respectively. We found that most functional hubs exhibited fair to good TRT reliability using intraclass correlation coefficients. Interestingly, our analysis suggested that a 6-minute scan duration was able to reliably detect these functional hubs. Further comparison analysis revealed that these results were approximately consistent with those obtained using traditional R-fMRI scans of the same subjects with TR=2500 ms, but several regions (e.g., lateral frontal cortex, paracentral lobule and anterior temporal lobe) exhibited different TRT reliability. Finally, we showed that several regions (including the medial/lateral prefrontal cortex and lateral temporal cortex) were identified as brain hubs in a high frequency band (0.2-0.3 Hz), which is beyond the frequency scope of traditional R-fMRI scans. Our results demonstrated the validity of multiband R-fMRI data to reliably detect functional hubs in the voxel-wise whole-brain networks, which motivated the acquisition of high temporal resolution R-fMRI data for the studies of human brain functional connectomes in healthy and diseased conditions.

[Study on BS-12 as a new probe for the determination of DNA by resonance light scattering].

A new method has been developed for the determination of DNA by resonance light scattering with dodecyl dimethyl betaine (BS-12) in aqueous solution as a new probe. At pH 9.3, the interactions of BS-12 and DNA gave strong RLS signals at 388.0 nm. Linear relationships were found between the enhanced intensity of RLS and the concentration of DNAs in the range 0.25-12.0 microg x mL(-1) for fsDNA and 0.25-11.0 microg x mL(-1) for ctDNA. The limits of detection were 0.15 ng x mL(-1) and 0.16 ng x mL(-1) for fsDNA and ctDNA, respectively. The method was applied to the determination of synthetic samples with satisfactory results.