Menon R S, Ogawa S, Strupp J P, Uğurbil K
Advanced Imaging Laboratories, The John P. Robarts Research Institute, London, Ontario, Canada.
J Neurophysiol. 1997 May;77(5):2780-7. doi: 10.1152/jn.1997.77.5.2780.
Very high resolution functional magnetic resonance imaging (fMRI) at a 4 Tesla (T) magnetic field was used to map ocular dominance regions in the human visual cortical layers using the blood oxygen level dependent (BOLD) contrast mechanism. The fMRI response from primary visual cortex (V1) exhibited a distribution of ocular dominance reminiscent of the single-cell recordings of Hubel and Wiesel. Pixels could be grouped into seven categories varying from left-only response to binocular-only response to right-only responses. Nonspecific responses were found in the MRI-visible draining veins as well as in the parenchyma. Although large vessel BOLD signals are easily detectable, regardless of field strength, they demonstrate a fMRI response to photic input that could not be used to distinguish ocular dominance. The difference in BOLD response between a region activated by one eye and that activated by the other is only 2.9% on average. This necessitates the use of a difference paradigm to visualize the regions of ocular dominance accurately. The data show that BOLD-based fMRI is sensitive to neuronal activity in cortical columns when using differential techniques, opening up the possibility of mapping specialized populations of neurons in humans that are not accessible to electrophysiological or other methods of invasive mapping.
在4特斯拉（T）磁场下进行的超高分辨率功能磁共振成像（fMRI），利用血氧水平依赖（BOLD）对比机制，绘制人类视觉皮层各层的眼优势区域。初级视觉皮层（V1）的fMRI反应呈现出一种眼优势分布，这让人联想到Hubel和Wiesel的单细胞记录。像素可分为七类，从仅对左眼的反应到仅对双眼的反应，再到仅对右眼的反应。在MRI可见的引流静脉以及实质中发现了非特异性反应。尽管无论场强如何，大血管的BOLD信号都很容易检测到，但它们显示出对光刺激输入的fMRI反应，而这种反应无法用于区分眼优势。一只眼睛激活的区域与另一只眼睛激活的区域之间的BOLD反应差异平均仅为2.9%。这就需要使用差异范式来准确可视化眼优势区域。数据表明，当使用差异技术时，基于BOLD的fMRI对皮质柱中的神经元活动敏感，这为绘制人类中电生理或其他侵入性绘图方法无法触及的特殊神经元群体开辟了可能性。
