Smith-Kettlewell Eye Research Institute, San Francisco, California 94115, USA.
J Neurosci. 2012 Aug 29;32(35):12180-91. doi: 10.1523/JNEUROSCI.5992-11.2012.
Attention is thought to operate by enhancing the target of interest and suppressing the surroundings. We hypothesized that the spatial profile of attention depends on the surround's relationship to the target. Using high-density electroencephalographic measurements, we examined the spatial profile of attention to a grating target surrounded by an annular grating that was either coextensive with the target (unsegmented) or appeared segmented from it due to a gap or phase offset. We directly probed the spread of attention from the central target into the surround by flickering the surround and monitoring frequency-tagged steady-state visual-evoked potentials. Observers were required to detect a contrast increment that occurred only on the target. Successful detection of the increment required selecting the target and suppressing the surround, particularly when the target did not readily segment from the surround. The profile of attention was investigated in five visual regions of interest (ROIs) (V1, V4, V3A, lateral occipital complex, and human middle temporal area), mapped in a separate anatomical magnetic resonance imaging scan. We found that in most ROIs, attention to the target generated smaller responses from the surrounding annulus when it was contiguous compared with when it was clearly segmented. This result shows that the profile of attention depends on task demands and on surrounding context; attention is tightly focused when the target region needs to be isolated but loosely focused when the target region is clearly segmented.
注意被认为是通过增强感兴趣的目标并抑制周围环境来运作的。我们假设注意的空间分布取决于周围环境与目标的关系。我们使用高密度脑电图测量，检查了光栅目标周围的环形光栅的注意空间分布，该光栅与目标（不分段）或由于间隙或相位偏移而与目标（分段）分开。我们通过闪烁环绕物并监测频率标记的稳态视觉诱发电位，直接探测注意力从中央目标向周围环境的扩展。要求观察者检测仅在目标上发生的对比度增量。成功检测到增量需要选择目标并抑制周围环境，尤其是当目标不易与周围环境区分时。我们在五个感兴趣的视觉区域（ROI）（V1、V4、V3A、外侧枕叶复合体和人类颞中回）中研究了注意力的分布，这些 ROI 是在单独的解剖磁共振成像扫描中映射的。我们发现，在大多数 ROI 中，与明显分段相比，当周围的环连续时，目标的注意力会导致周围环的响应变小。该结果表明，注意力的分布取决于任务需求和周围环境；当目标区域需要隔离时，注意力会高度集中，而当目标区域明显分段时，注意力会分散。
