Büchel C, Friston K J
The Wellcome Department of Cognitive Neurology, Institute of Neurology, London, UK.
Cereb Cortex. 1997 Dec;7(8):768-78. doi: 10.1093/cercor/7.8.768.
Electrophysiological and neuroimaging studies have shown that attention to visual motion can increase the responsiveness of the motion-selective cortical area V5 and the posterior parietal cortex (PP). Increased or decreased activation in a cortical area is often attributed to attentional modulation of the cortical projections to that area. This leads to the notion that attention is associated with changes in connectivity. We have addressed attentional modulation of effective connectivity using functional magnetic resonance imaging (fMRI). Three subjects were scanned under identical stimulus conditions (visual motion) while varying only the attentional component of the task. Haemodynamic responses defined an occipito-parieto-frontal network, including the, primary visual cortex (V1), V5 and PR A structural equation model of the interactions among these dorsal visual pathway areas revealed increased connectivity between V5 and PP related to attention. On the basis of our analysis and the neuroanatomical pattern of projections from the prefrontal cortex to PP we attributed the source of modulatory influences, on the posterior visual pathway, to the prefrontal cortex (PFC). To test this hypothesis we included the PFC in our model as a 'modulator' of the pathway between V5 and PP, using interaction terms in the structural equation model. This analysis revealed a significant modulatory effect of prefrontal regions on V5 afferents to posterior parietal cortex.
电生理和神经影像学研究表明，对视觉运动的注意可增强运动选择性皮层区域V5和顶叶后皮质（PP）的反应性。皮层区域激活的增加或减少通常归因于对该区域皮层投射的注意调制。这就产生了注意力与连接性变化相关的概念。我们使用功能磁共振成像（fMRI）研究了有效连接性的注意调制。三名受试者在相同的刺激条件（视觉运动）下接受扫描，同时仅改变任务的注意成分。血液动力学反应确定了一个枕-顶-额网络，包括初级视觉皮层（V1）、V5和PP。这些背侧视觉通路区域之间相互作用的结构方程模型显示，与注意力相关的V5和PP之间的连接性增加。基于我们的分析以及前额叶皮层向PP的神经解剖投射模式，我们将后视觉通路的调节影响源归因于前额叶皮层（PFC）。为了验证这一假设，我们在结构方程模型中使用交互项，将PFC作为V5和PP之间通路的“调制器”纳入我们的模型。该分析揭示了前额叶区域对V5向后顶叶皮层传入纤维的显著调制作用。
