Progress Report
Protecting children's intellectual curiosity and individuality to realize a dynamic society[1] Visualization of Children's Mental Well-being
Progress until FY2023
1. Outline of the project
The role of the research and development project "Assessment of Brain Individuality and Evaluation of Intervention Effects" is to explain the inherent characteristics of conditions such as Autism Spectrum Disorder (ASD) using both cognitive psychology and neuroscience (e.g., infant magnetoencephalography), enabling caregivers to view children in a more objective manner. The objective is to build scientific evidence to dispel misconceptions such as "developmental disorders caused by parenting" among families struggling with child-rearing and to prevent disharmony within the home (including parental maladaptation and abuse).
The role of the research and development project "Advanced Element Development of Brain-Measurement System Optimized for Children" is to explore the feasibility of applying optically pumped magnetometers (OPM) to infants in order to make the ASD diagnostic system more affordable and practical. It aims to verify whether OPM-MEG can replicate the results of previous studies conducted with SQUID-MEG.
2. Outcome so far
In "Evaluation of Brain Individuality and Intervention Effects," we have started recruiting participants and accumulating data. To facilitate smooth recruitment for this project, we have created a website and a dedicated site for participants. We have been analyzing brain network characteristics using graph theory to obtain brain indices reflecting the individuality of children.
Using this analytical method, we have reported a decrease in small-worldness in children with ASD tendencies compared to typically developing children (Shiota et al., 2022, Front Psychiatry). By applying similar analysis techniques, we conducted preliminary analysis of data from clinical trials of transcranial direct current stimulation (tDCS) in the past and demonstrated the potential to predict responders to working memory enhancement in adult males (Hirosawa et al., 2023, Front Psychiatry).
Regarding the "Development of Advanced Elements for an Optimized Brain Magnetic Measurement System for Children," sensory responses such as auditory evoked responses were detected in adult subjects using the latest generation of OPM sensors (Quspin's QZFM Gen.3). Furthermore, by developing a method for aligning sensor positions with brain structural data, we succeeded in pinpointing the locations of brain activity even with a significantly smaller number of sensors (12) compared to conventional MEG, by adopting an estimation algorithm that effectively utilizes the information (left figure). Additionally, anticipating measurements in children, we are also working on the development of a magnetic field gradient control system to accommodate body movements during measurement. We have built a system to cancel the residual magnetic field gradients, which persist even after shielding environmental magnetic fields such as geomagnetism with a shielded room, by applying a cancellation field through current coils introduced inside the shielded room. This system evaluates the effectiveness of this approach and has successfully demonstrated the principle of magnetic field gradient cancellation.
3. Future plans
Moving forward, we will continue to maximize the advantages of the high temporal resolution of magnetoencephalography (MEG) data and the higher spatial resolution compared to electroencephalography (EEG). We will advance the analysis of brain networks through graph analysis, expressing network features with metrics such as node degree, nodal efficiency, clustering coefficient, average path length, small-worldness, and network vulnerability. By doing so, we aim to clarify the relationship between these network characteristics and individual traits, including those of children.
Additionally, we will further optimize OPM measurements to make MEG more suitable for children. Specifically, we will focus on building a system to suppress magnetic field gradients and temporal variations. To achieve this, we will monitor spatial and temporal variations within the shielded room using auxiliary sensors, and simultaneously cancel magnetic field gradients in all directions. This will enable the stable operation of OPMs and the extraction of signals originating from brain neural activity by combining methods for signal processing and source estimation. These technologies will also be demonstrated for measurements in children.