Abstract
Human perception and cognition are based predominantly on visual information processing. Much of the information regarding neuronal correlates of visual processing has been derived from functional imaging studies, which have identified a variety of brain areas contributing to visual analysis, recognition, and processing of objects and scenes. However, only two of these areas, namely the parahippocampal place area (PPA) and the lateral occipital complex (LOC), were verified and further characterized by intracranial electroencephalogram (iEEG). iEEG is a unique measurement technique that samples a local neuronal population with high temporal and anatomical resolution. In the present study, we aimed to expand on previous reports and examine brain activity for selectivity of scenes and objects in the broadband high-gamma frequency range (50–150 Hz). We collected iEEG data from 27 epileptic patients while they watched a series of images, containing objects and scenes, and we identified 375 bipolar channels responding to at least one of these two categories. Using K-means clustering, we delineated their brain localization. In addition to the two areas described previously, we detected significant responses in two other scene-selective areas, not yet reported by any electrophysiological studies; namely the occipital place area (OPA) and the retrosplenial complex. Moreover, using iEEG we revealed a much broader network underlying visual processing than that described to date, using specialized functional imaging experimental designs. Here, we report the selective brain areas for scene processing include the posterior collateral sulcus and the anterior temporal region, which were already shown to be related to scene novelty and landmark naming. The object-selective responses appeared in the parietal, frontal, and temporal regions connected with tool use and object recognition. The temporal analyses specified the time course of the category selectivity through the dorsal and ventral visual streams. The receiver operating characteristic analyses identified the PPA and the fusiform portion of the LOC as being the most selective for scenes and objects, respectively. Our findings represent a valuable overview of visual processing selectivity for scenes and objects based on iEEG analyses and thus, contribute to a better understanding of visual processing in the human brain.
Highlights
Scene and object visual perception form the fundamentals of our understanding of the world around us
Besides the visual perception areas in the ventral stream, we found significant activity in areas previously reported to be associated with scene novelty, scene construction, object recognition, and object tool use
Selective processing for scenes was apparent in parts of the anterior temporal lobe, associated with scene novelty, such as the hippocampus and the anterior parahippocampal gyrus
Summary
Scene and object visual perception form the fundamentals of our understanding of the world around us. Visual perception of everyday objects evokes a larger hemodynamic response than the perception of scrambled objects in the lateral OC extending to the posterior lateral and the basal temporal regions. This area was originally described as the lateral occipital complex (LOC; Malach et al, 1995), and later subdivided into two functional portions (GrillSpector et al, 1999): the posterior (labeled LO), and the anterior, localized in the posterior fusiform gyrus (labeled pFs). Scene and object perception are highly interconnected; object perception is dependent on scene context, and the incorporated objects influence scene recognition (Brandman and Peelen, 2017)
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