Low-frequency variability in theta activity modulates the attention-fluctuation across task and resting states.

Sustained attention is not constant but fluctuates influencing our task performance. Albeit intensive investigations, it remains unclear whether the attention-fluctuation during tasks is derived from its spontaneous fluctuation in the resting state. Here, we addressed this issue by investigating the attention-fluctuation in both task and resting states, through the EEG measurement of theta-variability. We found significant rest-task modulation of theta-variability, i.e., reduced theta-variability in the task state compared to the resting state. This task and rest modulation was manifested in the low-frequency of theta-variability (<0.1 Hz). Furthermore, the low-frequency theta-variability exhibited a significant rest-task correlation, however, only the low-frequency theta-variability in the task state but not in the resting state was correlated with the behavioral performance. These findings shed light on the low-frequency feature of attention-fluctuation, and advanced our understanding of sustained attention by suggesting that the theta-variability in low-frequencies was relevant to attention level in task state.

A Predictive Model Offor Attention Deficit Hyperactivity Disorder Based on Clinical Assessment Tools.

BACKGROUND: At present, clinicians diagnose that the clinical diagnosis of attention deficit hyperactivity disorder (ADHD) in children is mainly on the basis of the information provided by their parents, the behaviour of children in clinical clinics and the assessments of clinical rating scales and neuropsychological tests. Notably, no unified standard exists currently for analysing the results of various measurement tools for diagnosing ADHD. Therefore, clinicians interpret the results of clinical rating scales and neuropsychological tests entirely based on their clinical experience. METHODS AND SUBJECTS: To provide guidance for clinicians on how to analyse the results of various clinical assessment tools when diagnosing ADHD, this study assessed children with ADHD and children in the control group using two clinical assessment scales-parent rating scale (PSQ) and Child Behavior Checklist (CBCL)-and one neuropsychological test (Integrated Visual and Auditory Continuous Performance Testing). The two-sample t-test (FDR correction) screened the parameters of the three assessment tools with significant inter-group differences. LibSVM was used to establish a classification prediction model for analysing the accuracy of ADHD prediction using parameters of the three assessment tools and weight values of each parameter for classification prediction. RESULTS: A total of 19 parameters (16 from clinical rating scales, 3 from neuropsychological tests) with significant inter-group differences were screened. The accuracy of classification modelling was higher for the clinical rating scales (61.635%) than for the neuropsychological test (59.784%), whereas the accuracy of classification modelling was higher for the clinical rating scales combined with the neuropsychological test (70.440%) than for the former two parameters alone. The three parameters with the highest weight values were learning problem (0.731), hyperactivity/impulsivity (0.676) and activity capacity (0.569). The three parameters with the lowest weight values are integrated control force (0.028), visual attention (0.028) and integrated attention (0.034). CONCLUSION: Our study findings indicate that the diagnosis of ADHD should be based on multidimensional assessment. For a more accurate diagnosis of ADHD, assessments and that more assessment parameters should be developed on the basis of different dimensions of physiology or psychology in the future to obtain a more accurate diagnosis of ADHD. Furthermore, the predictive model for ADHD may improve our understanding and help in optimisation of the treatment of such a condition.

The Inter-Regional Connectivity Within the Default Mode Network During the Attentional Processes of Internal Focus and External Focus: An fMRI Study of Continuous Finger Force Feedback.

Sustained attention involves two distinct processes, i.e., external focus and internal focus. Some recent neuroimaging studies employed the instruction of experimenters or the self-report from participants to generate the two attentional processes, and observed that the default mode network (DMN) was also responding to the external focus. These observations challenged the general view that the DMN accounts for the internally directed cognition, e.g., unfocused mind wandering, task independent-thoughts and internally focused events. Notably, the instruction or self-report may not effectively ensure the participants engage in the external focus/internal focus, and thus, the functional significance of the DMN for the externally focused process remains to be verified. In the present study, a new task paradigm, i.e., real/sham continuous feedback of finger force, was employed to generate the attentional process of external focus/internal focus, and the functional connectivity among the node regions of the DMN was further investigated in the two processes respectively. We found that two regions of the DMN, posterior cingulate cortex and left inferior parietal cortex/angular gyrus showed stronger inter-regional connectivity in the externally focused process than it in the internally focused process. Intriguingly, this functional connectivity was closely related to the behavioral performance in the process of external focus. These findings implicated that the functional significance of the DMN in sustained attention was more than responding to the internally directed cognition, and the task paradigm of continuous finger force feedback could benefit for the future studies on the externally focused/internally focused process of sustained attention.

Inconsistency in Abnormal Functional Connectivity Across Datasets of ADHD-200 in Children With Attention Deficit Hyperactivity Disorder.

Many studies have shown abnormal functional connectivity in children with attention deficit hyperactivity disorder (ADHD) by using resting-state functional magnetic resonance imaging (rs-fMRI). However, few studies illustrated that to what extent these findings were consistent across different datasets. The present study aimed to assess the consistency of abnormal functional connectivity in children with ADHD across the four datasets from a public-assess rs-fMRI ADHD cohort, namely, ADHD-200. We employed the identical analysis process of previous studies and examined a few factors, including connectivity with the seed regions of the bilateral dorsal anterior cingulate cortex, bilateral inferior frontal gyrus, and bilateral middle frontal gyrus; connectivity between default mode network and executive control network; stringent and lenient statistical thresholds; and the ADHD subtypes. Our results revealed a high inconsistency of abnormal seed-based connectivity in children with ADHD across all datasets, even across three datasets from the same research site. This inconsistency could also be observed with a lenient statistical threshold. Besides, each dataset did not show abnormal connectivity between default mode network and executive control network for ADHD, albeit this abnormal connectivity between networks was intensively reported in previous studies. Importantly, the ADHD combined subtype showed greater consistency than did the inattention subtype. These findings provided methodological insights into the studies on spontaneous brain activity of ADHD, and the ADHD subtypes deserve more attention in future studies.

A virtual reality application for assessment for attention deficit hyperactivity disorder in school-aged children.

Background and objective: The development of objective assessment tools for attention deficit hyperactivity disorder (ADHD) has become a hot research topic in recent years. This study was conducted to explore the feasibility and availability of virtual reality (VR) for evaluating symptoms of ADHD. Methods: School-aged children were recruited. The children with ADHD or without ADHD were assigned into the ADHD group or Control group, respectively. They were all evaluated using the Conners' Parent Rating Scale (CPRS), Child Behavior Checklist (CBCL), Integrated Visual and Auditory Continuous Performance Test (IVA-CPT), and a VR test. Results: The correct items, incorrect items, and the accuracy rate of the VR test of the children with ADHD were significantly different with those of the children in the Control group. The correct items, incorrect items, total time, and accuracy of the VR test were significantly correlated with the scores of IVA-CPT (auditory attention and visual attention), CPRS (impulsion/hyperactivity and ADHD index), and CBCL (attention problems and social problems), respectively. Discussion: The results supported the discriminant validity of the VR test for evaluating ADHD in school-age children suffering from learning problems. The VR test results are associated with the commonly used clinical measurements results. A VR test is interesting for children and therefore it attracts them to complete the test; whilst at the same time, it can also effectively evaluate ADHD symptoms.

Characteristics of brain functional and structural connectivity in alexithymic students.

BACKGROUND: Alexithymia is a multifaceted personality trait and a risk factor for several mental and physical diseases. METHODS: In this study, 21 alexithymic students and 21 nonalexithymic students were recruited from the local university and assigned to the alexithymic group and the control group, respectively. Then, the functional connectivity and the structural connectivity among the brain regions of the students were investigated using resting-state functional magnetic resonance imaging (rsfMRI), function connection (FC) analysis, and diffusion tensor imaging (DTI). RESULTS: The rsfMRI results revealed 14 brain regions showing significant differences in the amplitude of low-frequency fluctuations between the two groups. Comparative analysis of the FC and DTI data in these brain regions between the two groups identified altered levels of functional and structural connectivity between the following four pairs of regions in the alexithymic subjects: the right inferior temporal gyrus and the central posterior gyrus, the left temporal gyrus and the insula, and the bilateral superior frontal gyrus and the anterior cingulate gyrus. CONCLUSION: Compared with single MRI analysis, the multiple MRI analysis identified more precisely the brain regions that could play a key role in the development of alexithymia.

Variants of Dopamine Beta Hydroxylase Gene Moderate Atomoxetine Response in Children with Attention-Deficit/Hyperactivity Disorder.

OBJECTIVE: Atomoxetine is the most widely used nonstimulant for the treatment of attention-deficit/hyperactivity disorder (ADHD). It selectively acts on the norepinephrine (NE) system. Dopamine beta hydroxylase (DBH) regulates the synthesis of NE. This study aimed to investigate whether variants in the DBH gene have an effect on the differential response to atomoxetine. METHODS: Children and adolescents with ADHD were enrolled in a prospective, open-label study of atomoxetine for 8-12 weeks. The dose was titrated to 1.2-1.4 mg/kg per day and maintained for at least 4 weeks. The primary efficacy measure was the investigator-rated ADHD Rating Scale-IV (ADHD-RS-IV). Three categorical evaluations of treatment effects (defined as response, robust response, and remission) were used. We used a candidate gene approach. Eight single nucleotide polymorphisms (SNPs) in DBH were selected and genotyped based on the functional annotation in literature. Their association with response or remission status was analyzed. RESULTS: Four SNPs were found nominally associated with response status (rs1076150, p = 0.0484; rs2873804, p = 0.0348; rs1548364, p = 0.0383; and rs2519154, p = 0.0097), two were associated with robust response (rs1076150, p = 0.0349; and rs2519154, p = 0.0047), and one was associated with remission (rs2519154, p = 0.0479). The association between rs2519154 and robust response was significant after correction of multiple comparison (p = 0.0384). Two haplotypes of linkage disequilibrium (LD) block1 (constituted by rs1108580, rs2873804, rs1548364, and rs2519154) were nominally associated with response and robust response status (CTAC: p = 0.0301 for response, p = 0.0374 for robust response; TCGT: p = 0.0317 for response, p = 0.021 for robust response), whereas one haplotype (GC) of LD block2 (constituted by rs2073837 and rs129882) was associated with robust response and remission status (p = 0.0377 for robust response; p = 0.0321 for remission), although none achieved significant threshold after multiple comparison. CONCLUSIONS: Variants in DBH genes were associated with atomoxetine response in the treatment of ADHD. Further replication in larger samples would be warranted.