High-resolution quantitative and functional MRI indicate lower myelination of thin and thick stripes in human secondary visual cortex.
High-resolution quantitative and functional MRI indicate lower myelination of thin and thick stripes in human secondary visual cortex.
复制标题
高分辨率定量和功能性MRI表明人类次级视觉皮层中薄和厚条纹的髓鞘降低。
DOI：
10.7554/elife.78756
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发表时间：
2023-03-08
期刊：
影响因子：
7.7
通讯作者：
Weiskopf N
中科院分区：
文献类型：
--
作者：
Haenelt D;Trampel R;Nasr S;Polimeni JR;Tootell RBH;Sereno MI;Pine KJ;Edwards LJ;Helbling S;Weiskopf N
皮层髓鞘形成的表征对于研究人脑结构-功能关系至关重要。然而，关于皮质髓鞘形成的知识在很大程度上是基于死后组织学，这通常使得直接比较功能是不可能的。灵长类动物第二视觉皮层（V2）细胞色素氧化酶（CO）活性的淡-薄-淡-厚条纹重复模式是一个突出的柱状系统，其组织学也表明薄/厚与淡条纹的髓鞘形成不同。我们使用定量磁共振成像（qMRI）结合超高场强（7 T）的功能磁共振成像（fMRI）来定位和研究四名人类参与者体内亚毫米分辨率的条纹髓鞘形成。细条纹和粗条纹分别利用其对颜色的敏感性和双眼视差进行功能定位。所得到的功能激活图显示了V2中稳健的条纹模式，这使得条纹类型之间的定量松弛参数可以进一步比较。因此，我们发现，与周围灰质相比，薄条纹和厚条纹的纵向松弛率（R1）较低，约为1-2%，表明浅色条纹的髓鞘化程度较高。有效横向弛豫率没有一致的差异（R2*）。该研究证明了在柱状系统水平上使用qMRI在一个皮层区域内研究活人结构-功能关系的可行性。
The characterization of cortical myelination is essential for the study of structure-function relationships in the human brain. However, knowledge about cortical myelination is largely based on post-mortem histology, which generally renders direct comparison to function impossible. The repeating pattern of pale-thin-pale-thick stripes of cytochrome oxidase (CO) activity in the primate secondary visual cortex (V2) is a prominent columnar system, in which histology also indicates different myelination of thin/thick versus pale stripes. We used quantitative magnetic resonance imaging (qMRI) in conjunction with functional magnetic resonance imaging (fMRI) at ultra-high field strength (7 T) to localize and study myelination of stripes in four human participants at sub-millimeter resolution in vivo. Thin and thick stripes were functionally localized by exploiting their sensitivity to color and binocular disparity, respectively. Resulting functional activation maps showed robust stripe patterns in V2 which enabled further comparison of quantitative relaxation parameters between stripe types. Thereby, we found lower longitudinal relaxation rates (R1) of thin and thick stripes compared to surrounding gray matter in the order of 1–2%, indicating higher myelination of pale stripes. No consistent differences were found for effective transverse relaxation rates (R2*). The study demonstrates the feasibility to investigate structure-function relationships in living humans within one cortical area at the level of columnar systems using qMRI.