Mononen Riikka, Saarela Toni, Vallinoja Jaakko, Olkkonen Maria, Henriksson Linda
Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo FI-00076, Finland.
MEG Core, Aalto NeuroImaging, Aalto University, Espoo FI-00076, Finland.
J Neurosci. 2025 Feb 26;45(9):e2157232024. doi: 10.1523/JNEUROSCI.2157-23.2024.
Our visual system enables us to effortlessly navigate and recognize real-world visual environments. Functional magnetic resonance imaging (fMRI) studies suggest a network of scene-responsive cortical visual areas, but much less is known about the temporal order in which different scene properties are analyzed by the human visual system. In this study, we selected a set of 36 full-color natural scenes that varied in spatial structure and semantic content that our male and female human participants viewed both in 2D and 3D while we recorded magnetoencephalography (MEG) data. MEG enables tracking of cortical activity in humans at millisecond timescale. We compared the representational geometry in the MEG responses with predictions based on the scene stimuli using the representational similarity analysis framework. The representational structure first reflected the spatial structure in the scenes in time window 90-125 ms, followed by the semantic content in time window 140-175 ms after stimulus onset. The 3D stereoscopic viewing of the scenes affected the responses relatively late, from ∼140 ms from stimulus onset. Taken together, our results indicate that the human visual system rapidly encodes a scene's spatial structure and suggest that this information is based on monocular instead of binocular depth cues.
我们的视觉系统使我们能够轻松地在现实世界的视觉环境中导航和识别。功能磁共振成像（fMRI）研究表明存在一个对场景有反应的皮质视觉区域网络，但对于人类视觉系统分析不同场景属性的时间顺序却知之甚少。在这项研究中，我们选择了一组36个全彩自然场景，这些场景在空间结构和语义内容上各不相同，我们的男性和女性人类参与者在观看2D和3D场景时，我们记录了脑磁图（MEG）数据。MEG能够在毫秒时间尺度上跟踪人类的皮质活动。我们使用表征相似性分析框架，将MEG反应中的表征几何与基于场景刺激的预测进行了比较。表征结构首先在刺激开始后90 - 125毫秒的时间窗口内反映场景中的空间结构，随后在140 - 175毫秒的时间窗口内反映语义内容。对场景的3D立体观看对反应的影响相对较晚，从刺激开始约140毫秒起。综上所述，我们的结果表明人类视觉系统能快速编码场景的空间结构，并表明该信息基于单眼而非双眼深度线索。
