Deutschländer A, Marx E, Stephan T, Riedel E, Wiesmann M, Dieterich M, Brandt T
Department of Neurology, Klinikum Grosshadern, Munich, Germany.
Neuroimage. 2005 Oct 15;28(1):4-13. doi: 10.1016/j.neuroimage.2005.06.001. Epub 2005 Jul 6.
We used BOLD fMRI to study the differential effects of the direction of gaze on the visual and the ocular motor systems. Fixation of a target straight ahead was compared to fixation of a target 10 degrees to the right and 10 degrees to the left from gaze straight ahead, and to eyes open in complete darkness in thirteen healthy volunteers. While retinotopic coordinates remained the same in all fixation conditions, the fixation target shifted with respect to a head-centered frame of reference. During lateral fixation, deactivations in higher-order visual areas (one ventral cluster in the lingual and fusiform gyri and one dorsal cluster in the postero-superior cuneus) and, as a trend, activations in early visual cortical areas were found predominantly in the hemisphere contralateral to the fixation target. We propose that visual processing is performed predominantly in the hemisphere contralateral to gaze direction, even during small gaze shifts into one visual hemifield. The excitability of visual neurons may be modulated depending on eye position to construct a head-centered frame of reference from a retinotopic input, thus allowing perceptual stability of space during eye movements. A further finding was that BOLD signal increases in fronto-parietal ocular motor and attentional structures were more pronounced during lateral than central fixation.
我们使用血氧水平依赖性功能磁共振成像（BOLD fMRI）来研究注视方向对视觉和眼动系统的不同影响。在13名健康志愿者中，将直视前方目标的注视与从直视前方向右和向左各10度的目标注视，以及在完全黑暗中睁眼的情况进行了比较。虽然在所有注视条件下视网膜坐标保持不变，但注视目标相对于以头部为中心的参考框架发生了移动。在侧方注视期间，在高阶视觉区域（舌回和梭状回中的一个腹侧簇以及后上楔叶中的一个背侧簇）发现了失活，并且作为一种趋势，在早期视觉皮层区域的激活主要出现在与注视目标对侧的半球。我们提出，即使在小幅度的注视转移到一个视觉半视野时，视觉处理也主要在与注视方向对侧的半球中进行。视觉神经元的兴奋性可能会根据眼睛位置进行调节，以便从视网膜输入构建以头部为中心的参考框架，从而在眼球运动期间实现空间的感知稳定性。另一个发现是，与中央注视相比，侧方注视期间额顶叶眼动和注意力结构中的BOLD信号增加更为明显。
