Bles Mart, Schwarzbach Jens, De Weerd Peter, Goebel Rainer, Jansma Bernadette M
Maastricht University, Faculty of Psychology, Department of Cognitive Neuroscience, Maastricht, The Netherlands.
Neuroimage. 2006 Apr 1;30(2):506-11. doi: 10.1016/j.neuroimage.2005.09.042. Epub 2005 Oct 26.
Neurophysiological studies in monkeys show that multiple stimuli presented within the receptive field of a neuron are not processed independently but rather act in a mutually suppressive way. Recently, such suppressive interactions have also been reported in human neuroimaging studies. This is seen as evidence that stimuli compete for neural representation. According to the 'biased competition' approach, attention can bias this competition in favor of the attended stimulus, relieving it of the suppressive influences of the distracters. In this paper, we report data that support these findings. Specifically, the effect of attention on stimuli with different spatial separations was investigated more thoroughly. The biased competition approach would predict that, for a given spatial separation and eccentricity, the difference between attended and unattended displays depends on the receptive field size of an area. In a blocked fMRI experiment, participants viewed four simultaneously presented, colorful pictures under different attention conditions (attended and unattended). Stimuli were separated either 2 degrees , 4 degrees or 7 degrees . In line with previous experiments, we found that the effect of attention correlated with the estimated receptive field size of an area. In areas V1, V2 and VP, where estimated receptive field sizes are small, no significant attention effects were found in any of the spatial separation conditions. In V4, there was a significant difference between attended and unattended conditions for the 2 degrees and 4 degrees spatial separations, but not for 7 degrees . Finally in area TEO, significant differences between attended and unattended conditions were observed for all spatial separations.
对猴子的神经生理学研究表明，在一个神经元的感受野内呈现的多个刺激并非独立处理，而是以相互抑制的方式起作用。最近，在人类神经影像学研究中也报道了这种抑制性相互作用。这被视为刺激竞争神经表征的证据。根据“偏向竞争”方法，注意力可以使这种竞争偏向于被关注的刺激，减轻干扰物的抑制影响。在本文中，我们报告了支持这些发现的数据。具体而言，对注意力对具有不同空间间隔的刺激的影响进行了更深入的研究。偏向竞争方法预测，对于给定的空间间隔和偏心率，被关注和未被关注的显示之间的差异取决于一个区域的感受野大小。在一个分组的功能磁共振成像实验中，参与者在不同的注意力条件（被关注和未被关注）下观看四张同时呈现的彩色图片。刺激的间隔为2度、4度或7度。与先前的实验一致，我们发现注意力的影响与一个区域的估计感受野大小相关。在V1、V2和VP区域，估计的感受野较小，在任何空间间隔条件下均未发现显著的注意力效应。在V4区域，对于2度和4度的空间间隔，被关注和未被关注条件之间存在显著差异，但对于7度则没有。最后在TEO区域，在所有空间间隔下均观察到被关注和未被关注条件之间的显著差异。
