近日，刊登在新一期美國《國家科學(xué)院院刊》（PNAS）上的一個(gè)縱向研究報(bào)告宣稱,，兒童的閱讀能力可能在很大程度上取決于一個(gè)人的腦回路已經(jīng)充分發(fā)育但是仍然有生長能力的時(shí)期,。
一般而言，大腦白質(zhì)組織特性與閱讀熟練性有很高的關(guān)聯(lián)性,，研究人員試圖建立一個(gè)模型來展示個(gè)體的白質(zhì)發(fā)育狀況與其閱讀能力之間的關(guān)系,。白質(zhì)是大腦內(nèi)部神經(jīng)纖維聚集的地方，參與從一個(gè)區(qū)域向另一個(gè)區(qū)域傳遞信號,。大腦白質(zhì)的發(fā)育包括多重生物過程,，并且這些過程之間的平衡性因人而異。
美國斯坦福大學(xué)心理學(xué)系的Jason Daniel Yeatman及其同事追蹤了55名7到12歲兒童在3年時(shí)間里的閱讀熟練程度,。其中39名兒童接受了至少3次掃描,，研究人員測量了與閱讀技能有關(guān)的大腦區(qū)域的發(fā)育。這些測量把重點(diǎn)放在了大腦白質(zhì)上,。
研究結(jié)果顯示,，盡管每一名兒童的閱讀技能都逐年增長,，但一般兒童的閱讀技能相對于同伴的相關(guān)技能而言并沒有顯著變化,。與其他兒童相比，那些擁有高于平均閱讀技能的兒童最初擁有較少發(fā)育的白質(zhì),，但其白質(zhì)在隨后的3年時(shí)間里不斷增加,。然而，那些閱讀能力在平均水平以下的兒童,，白質(zhì)的發(fā)育隨著時(shí)間推移而減少,。
這組作者提出，當(dāng)一個(gè)人的大腦回路充分發(fā)育,，但是仍保有進(jìn)一步可塑性的潛力的時(shí)候,，閱讀教育或許應(yīng)該被考慮進(jìn)來。這種發(fā)育時(shí)機(jī)可能不僅依賴于年齡,，而且依賴于其他可能驅(qū)動這個(gè)過程的因素,，諸如遺傳和此前的生活體驗(yàn)等。因此,，未來兒童或許能從專門適合他們的特定大腦發(fā)育階段接受適時(shí)的教育,，并從中獲益。（生物谷Bioon.com）
doi:10.1073/pnas.1206792109
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Development of white matter and reading skills
Jason D. Yeatmana,Robert F. Dougherty, Michal Ben-Shachar, and Brian A. Wandella
White matter tissue properties are highly correlated with reading proficiency; we would like to have a model that relates the dynamics of an individual’s white matter development to their acquisition of skilled reading. The development of cerebral white matter involves multiple biological processes, and the balance between these processes differs between individuals. Cross-sectional measures of white matter mask the interplay between these processes and their connection to an individual’s cognitive development. Hence, we performed a longitudinal study to measure white-matter development (diffusion-weighted imaging) and reading development (behavioral testing) in individual children (age 7–15 y). The pattern of white-matter development differed significantly among children. In the left arcuate and left inferior longitudinal fasciculus, children with above-average reading skills initially had low fractional anisotropy (FA) that increased over the 3-y period, whereas children with below-average reading skills had higher initial FA that declined over time. We describe a dual-process model of white matter development comprising biological processes with opposing effects on FA, such as axonal myelination and pruning, to explain the pattern of results.
