Investigating the Impact of the Missing Significant Objects in Scene Recognition Using Multivariate Pattern Analysis.

Significant objects in a scene can make a great contribution to scene recognition. Besides the three scene-selective regions: parahippocampal place area (PPA), retrosplenial complex (RSC), and occipital place area (OPA), some neuroimaging studies have shown that the lateral occipital complex (LOC) is also engaged in scene recognition processing. In this study, the multivariate pattern analysis was adopted to explore the object-scene association in scene recognition when different amounts of significant objects were masked. The scene classification only succeeded in the intact scene in the ROIs. In addition, the average signal intensity in LOC [including the lateral occipital cortex (LO) and the posterior fusiform area (pF)] decreased when there were masked objects, but such a decrease was not observed in scene-selective regions. These results suggested that LOC was sensitive to the loss of significant objects and mainly involved in scene recognition by the object-scene semantic association. The performance of the scene-selective areas may be mainly due to the fact that they responded to the change of the scene's entire attribute, such as the spatial information, when they were employed in the scene recognition processing. These findings further enrich our knowledge of the significant objects' influence on the activation pattern during the process of scene recognition.

Investigating the Brain Neural Mechanism when Signature Objects were Masked during a Scene Categorization Task using Functional MRI.

Objects play vital roles in scene categorization. Although a number of studies have researched on the neural responses during object and object-based scene recognition, few studies have investigated the neural mechanism underlying object-masked scene categorization. Here, we used functional magnetic resonance imaging (fMRI) to measure the changes in brain activations and functional connectivity (FC) while subjects performed a visual scene-categorization task with different numbers of 'signature objects' masked. The object-selective region in the lateral occipital complex (LOC) showed a decrease in activations and changes in FC with the default mode network (DMN), indicating changes in object attention after the masking of signature objects. Changes in top-down modulation effect were revealed in the FC from the dorsolateral prefrontal cortex (DLPFC) to LOC and the extrastriate visual cortex, possibly participating in conscious object recognition. The whole-brain analyses showed the participation of fronto-parietal network (FPN) in scene categorization judgment, and right DLPFC served as the core hub in this network. Another core hub was found in left middle temporal gyrus (MTG) and its connection with middle cingulate cortex (MCC), supramarginal gyrus (SMG) and insula might serve in the processing of motor response and the semantic relations between objects and scenes. Brain-behavior correlation analysis substantiated the contributions of the FC to the different processes in the object-masked scene-categorization tasks. Altogether, the results suggest that masking of objects significantly affected the object attention, cognitive demand, top-down modulation effect, and semantic judgment.