Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.
Hum Brain Mapp. 2010 Sep;31(9):1297-304. doi: 10.1002/hbm.20936.
The neocortex is known to have a distinct laminar structure which has previously been probed in animals using high-resolution fMRI. Detection of layer-specific activation in humans has however to date proven elusive. In this study we demonstrate for the first time such layer-specific activation, specifically at a depth corresponding to layer IV of human primary visual cortex (V1). We used a gradient-echo (GE) sequence at 3T with an isotropic resolution of 0.75 mm, in which a stria at the depth of layer IV was visible in the averaged time series, and could be used as an anatomical landmark. Upon visual stimulation (7.5 Hz flickering checkerboard) the signal increase of 3% in layer IV was significantly higher than in the neighboring laminae. The width of this activation peak was 0.8-1 mm. Based on this result and known laminar organization of the intracortical vasculature we conclude that in the direction perpendicular to the cortical surface the intrinsic spatial resolution of the GE-BOLD fMRI signal is in the submillimetre range. Human laminar fMRI is a significant development which may improve our understanding of intracortical activation patterns and of the way in which different cortical regions interact.
新皮层具有明显的分层结构，此前曾在动物中使用高分辨率 fMRI 进行探测。然而，到目前为止，在人类中检测到特定层的激活一直难以实现。在这项研究中，我们首次证明了这种特定层的激活，特别是在对应于人类初级视觉皮层（V1）IV 层的深度。我们使用了 3T 的梯度回波（GE）序列，各向同性分辨率为 0.75 毫米，在平均时间序列中可以看到 IV 层深度的条纹，可以将其用作解剖学标记。在视觉刺激（7.5 Hz 闪烁棋盘）下，IV 层的信号增加了 3%，明显高于相邻的层。这个激活峰的宽度为 0.8-1 毫米。基于这个结果和已知的皮质内血管的分层组织，我们得出结论，在垂直于皮质表面的方向上，GE-BOLD fMRI 信号的固有空间分辨率在亚毫米范围内。人类分层 fMRI 是一项重要的发展，它可能会提高我们对皮质内激活模式以及不同皮质区域相互作用方式的理解。
