คอลัมน์ Editor’s Choice ในวารสาร Science ฉบับวันที่ ๒๗ เมษายน ๒๕๖๑ แนะนำเรื่อง The brain as a work in progress นำผมไปสู่รายงานผลการวิจัยเรื่อง The Integration of Functional Brain Activity from Adolescence to Adulthood (1) ในวารสาร The Journal of Neuroscience ที่ใช้เครื่องมือสมัยใหม่คือ multiecho functional MRI (ME-fMRI) ตรวจระดับความเข้มข้นของอ็อกซิเจนในส่วนต่างๆ ของสมองของคน ๕๑ คน อายุตั้งแต่ ๘.๓ ขวบถึง ๔๖.๒ ปี และพบว่ามีการเปลี่ยนแปลงการทำงานของส่วนต่างๆ ในสมอง ที่เปลี่ยนแปลงมากที่สุดอยู่ที่ส่วนทำหน้าที่ EF และ coordination
การทดลองนี้ เน้นตรวจจับสัญญาณ BOLD (Blood Oxygenation Level Dependent) และพบว่า จำนวน BOLD Component น้อยลงเมื่ออายุมากขึ้น ซึ่งตรงกันข้ามกับความคาดหมายเดิม คือเมื่ออายุ ๔๒ ลดลงเหลือครึ่งหนึ่งของเมื่ออายุ ๘ ปี เขาตีความว่า เมื่ออายุมากขึ้นการทำงานของสมองมีการบูรณาการเชื่อมโยงกันเป็นหน่วยปฏิบัติหน้าที่เดียวกันมากขึ้น ตามสมมติฐานบูรณาการหน้าที่ของสมอง และเสนอว่าสมองส่วน cerebellum ทำหน้าที่หลักในการเปลี่ยนแปลงนี้
วิจารณ์ พานิช
๖ พ.ค. ๖๑
May I add the abstract from that article and highlight their finding?
Abstract
Age-related changes in human functional neuroanatomy are poorly understood. This is partly due to the limits of interpretation of standard fMRI. These limits relate to age-related variation in noise levels in data from different subjects, and the common use of standard adult brain parcellations for developmental studies. Here we used an emerging MRI approach called multiecho (ME)-fMRI to characterize functional brain changes with age. ME-fMRI acquires blood oxygenation level-dependent (BOLD) signals while also quantifying susceptibility-weighted transverse relaxation time (T2*) signal decay. This approach newly enables reliable detection of BOLD signal components at the subject level as opposed to solely at the group-average level. In turn, it supports more robust characterization of the variability in functional brain organization across individuals. We hypothesized that BOLD components in the resting state are not stable with age, and would decrease in number from adolescence to adulthood. This runs counter to the current assumptions in neurodevelopmental analyses of brain connectivity that the number of BOLD signal components is a random effect. From resting-state ME-fMRI of 51 healthy subjects of both sexes, between 8.3 and 46.2 years of age, we found a highly significant (r = −0.55, p ≪ 0.001) exponential decrease in the number of BOLD components with age. The number of BOLD components were halved from adolescence to the fifth decade of life, stabilizing in middle adulthood. The regions driving this change were dorsolateral prefrontal cortices, parietal cortex, and cerebellum. The functional network of these regions centered on the cerebellum. We conclude that an age-related decrease in BOLD component number concurs with the hypothesis of neurodevelopmental integration of functional brain activity. We show evidence that the cerebellum may play a key role in this process.
SIGNIFICANCE STATEMENT Human brain development is ongoing from childhood to at least 30 years of age. Functional MRI (fMRI) is key for characterizing changes in brain function that accompany development. However, developmental fMRI studies have relied on reference maps of adult brain organization in the analysis of data from younger subjects. This approach may limit the characterization of functional activity patterns that are particular to children and adolescents. Here we used an emerging fMRI approach called multi-echo fMRI that is not susceptible to such biases when analyzing the variation in functional brain organization over development. We hypothesized an integration of the components of brain activity over development, and found that the number of components decreases exponentially, halving from 8 to 35 years of age. The brain regions most affected underlie executive function and coordination. In summary, we show major changes in the organization and integration of functional networks over development into adulthood, with both methodological and neurobiological implications for future lifespan and disease studies on brain connectivity.
The bottom line is 'we learn less and less from age of 8'.
May I add the abstract from that article and highlight their finding?
Abstract
Age-related changes in human functional neuroanatomy are poorly understood. This is partly due to the limits of interpretation of standard fMRI. These limits relate to age-related variation in noise levels in data from different subjects, and the common use of standard adult brain parcellations for developmental studies. Here we used an emerging MRI approach called multiecho (ME)-fMRI to characterize functional brain changes with age. ME-fMRI acquires blood oxygenation level-dependent (BOLD) signals while also quantifying susceptibility-weighted transverse relaxation time (T2*) signal decay. This approach newly enables reliable detection of BOLD signal components at the subject level as opposed to solely at the group-average level. In turn, it supports more robust characterization of the variability in functional brain organization across individuals. We hypothesized that BOLD components in the resting state are not stable with age, and would decrease in number from adolescence to adulthood. This runs counter to the current assumptions in neurodevelopmental analyses of brain connectivity that the number of BOLD signal components is a random effect. From resting-state ME-fMRI of 51 healthy subjects of both sexes, between 8.3 and 46.2 years of age, we found a highly significant (r = −0.55, p ≪ 0.001) exponential decrease in the number of BOLD components with age. The number of BOLD components were halved from adolescence to the fifth decade of life, stabilizing in middle adulthood. The regions driving this change were dorsolateral prefrontal cortices, parietal cortex, and cerebellum. The functional network of these regions centered on the cerebellum. We conclude that an age-related decrease in BOLD component number concurs with the hypothesis of neurodevelopmental integration of functional brain activity. We show evidence that the cerebellum may play a key role in this process.
SIGNIFICANCE STATEMENT Human brain development is ongoing from childhood to at least 30 years of age. Functional MRI (fMRI) is key for characterizing changes in brain function that accompany development. However, developmental fMRI studies have relied on reference maps of adult brain organization in the analysis of data from younger subjects. This approach may limit the characterization of functional activity patterns that are particular to children and adolescents. Here we used an emerging fMRI approach called multi-echo fMRI that is not susceptible to such biases when analyzing the variation in functional brain organization over development. We hypothesized an integration of the components of brain activity over development, and found that the number of components decreases exponentially, halving from 8 to 35 years of age. The brain regions most affected underlie executive function and coordination. In summary, we show major changes in the organization and integration of functional networks over development into adulthood, with both methodological and neurobiological implications for future lifespan and disease studies on brain connectivity.
The bottom line is 'we learn less and less from age of 8'.