Windmann Sabine, Wehrmann Michaela, Calabrese Pasquale, Güntürkün Onur
University of Plymouth, UK.
J Cogn Neurosci. 2006 Mar;18(3):456-71. doi: 10.1162/089892906775990570.
The primary source of top-down attentional control in object perception is the prefrontal cortex. This region is involved in the maintenance of goal-related information as well as in attentional selection and set shifting. Recent approaches have emphasized the role of top-down processes during elementary visual processes as exemplified in bistable vision where perception oscillates automatically between two mutually exclusive states. The prefrontal cortex might influence this process either by maintaining the dominant pattern while protecting it against the competing representation, or by facilitating perceptual switches between the two competing representations. To address this issue, we investigated reported perceptual reversals in patients with circumscribed lesions of the prefrontal cortex and healthy control participants in three experimental conditions: hold (maintaining the dominant view), speed (inducing as many perceptual switches as possible), and neutral (no intervention). Results indicated that although the patients showed normal switching rates in the neutral condition and were able to control perceptual switches in the hold condition as much as control subjects were, they were less able to facilitate reversals specifically in the speed condition. These results suggest that the prefrontal cortex is necessary to bias the selection of visual representations in accord with current goals, but is less essential for maintaining selected information active that is continuously available in the environment. As for attentional selection, the present results suggest that the prefrontal cortex initiates perceptual reversals by withdrawing top-down support from the dominant representation without (or prior to) boosting the suppressed view.
在物体感知中，自上而下的注意力控制的主要来源是前额叶皮层。该区域参与与目标相关信息的维持，以及注意力的选择和定势转换。最近的研究方法强调了自上而下的过程在基本视觉过程中的作用，如在双眼竞争视觉中，感知会在两种相互排斥的状态之间自动振荡。前额叶皮层可能通过维持主导模式并保护其免受竞争表征的影响，或者通过促进两种竞争表征之间的感知切换来影响这一过程。为了解决这个问题，我们在三种实验条件下，对前额叶皮层有局限性损伤的患者和健康对照参与者报告的感知反转进行了研究：保持（维持主导视图）、快速切换（尽可能多地诱导感知切换）和中性（不干预）。结果表明，虽然患者在中性条件下表现出正常的切换率，并且在保持条件下能够像对照受试者一样控制感知切换，但他们在快速切换条件下促进反转的能力较弱。这些结果表明，前额叶皮层对于根据当前目标偏向视觉表征的选择是必要的，但对于在环境中持续可用的所选信息保持活跃来说并非必不可少。至于注意力选择，目前的结果表明，前额叶皮层通过在不增强（或在增强之前）被抑制视图的情况下，从主导表征中撤回自上而下的支持来启动感知反转。
