Tettamanti Marco, Conca Francesca, Falini Andrea, Perani Daniela
Division of Neuroscience and
Vita-Salute San Raffaele University, I-20132 Milano, Italy.
J Neurosci. 2017 Nov 1;37(44):10712-10724. doi: 10.1523/JNEUROSCI.1061-17.2017. Epub 2017 Oct 4.
The hypothesis that the brain constitutively encodes observed manipulable objects for the actions they afford is still debated. Yet, crucial evidence demonstrating that, even in the absence of perceptual awareness, the mere visual appearance of a manipulable object triggers a visuomotor coding in the action representation system including the premotor cortex, has hitherto not been provided. In this fMRI study, we instantiated reliable unaware visual perception conditions by means of continuous flash suppression, and we tested in 24 healthy human participants (13 females) whether the visuomotor object-directed action representation system that includes left-hemispheric premotor, parietal, and posterior temporal cortices is activated even under subliminal perceptual conditions. We found consistent activation in the target visuomotor cortices, both with and without perceptual awareness, specifically for pictures of manipulable versus non-manipulable objects. By means of a multivariate searchlight analysis, we also found that the brain activation patterns in this visuomotor network enabled the decoding of manipulable versus non-manipulable object picture processing, both with and without awareness. These findings demonstrate the intimate neural coupling between visual perception and motor representation that underlies manipulable object processing: manipulable object stimuli specifically engage the visuomotor object-directed action representation system, in a constitutive manner that is independent from perceptual awareness. This perceptuo-motor coupling endows the brain with an efficient mechanism for monitoring and planning reactions to external stimuli in the absence of awareness. Our brain constantly encodes the visual information that hits the retina, leading to a stimulus-specific activation of sensory and semantic representations, even for objects that we do not consciously perceive. Do these unconscious representations encompass the motor programming of actions that could be accomplished congruently with the objects' functions? In this fMRI study, we instantiated unaware visual perception conditions, by dynamically suppressing the visibility of manipulable object pictures with mondrian masks. Despite escaping conscious perception, manipulable objects activated an object-directed action representation system that includes left-hemispheric premotor, parietal, and posterior temporal cortices. This demonstrates that visuomotor encoding occurs independently of conscious object perception.
大脑是否会持续对可操作物体进行编码以反映其所能提供的动作，这一假设仍存在争议。然而，迄今尚未有关键证据表明，即使在没有感知意识的情况下，可操作物体的单纯视觉外观也会在包括运动前皮层在内的动作表征系统中触发视觉运动编码。在这项功能磁共振成像（fMRI）研究中，我们通过持续闪光抑制建立了可靠的无意识视觉感知条件，并在24名健康人类参与者（13名女性）中测试了即使在阈下感知条件下，包括左半球运动前区、顶叶和颞叶后部皮质在内的视觉运动目标导向动作表征系统是否会被激活。我们发现，无论有无感知意识，目标视觉运动皮层均出现一致性激活，特别是对于可操作与不可操作物体的图片。通过多变量搜索光分析，我们还发现该视觉运动网络中的大脑激活模式能够解码有无意识情况下可操作与不可操作物体图片的处理过程。这些发现证明了视觉感知与运动表征之间紧密的神经耦合，这是可操作物体处理的基础：可操作物体刺激以一种独立于感知意识的固有方式，特异性地激活视觉运动目标导向动作表征系统。这种感知 - 运动耦合赋予大脑一种有效的机制，用于在无意识状态下监测和规划对外部刺激的反应。我们的大脑持续对撞击视网膜的视觉信息进行编码，即使对于我们没有有意识感知到的物体，也会导致感觉和语义表征的刺激特异性激活。这些无意识表征是否包括与物体功能一致的动作的运动编程？在这项fMRI研究中，我们通过用蒙德里安面具动态抑制可操作物体图片的可见性，建立了无意识视觉感知条件。尽管避开了有意识的感知，但可操作物体激活了一个包括左半球运动前区、顶叶和颞叶后部皮质在内的目标导向动作表征系统。这表明视觉运动编码独立于有意识的物体感知而发生。
