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Objects and categories: feature statistics and object processing in the ventral stream.


Type

Article

Change log

Authors

Tyler, Lorraine K 
Chiu, Shannon 
Zhuang, Jie 
Randall, Billi 
Devereux, Barry J 

Abstract

Recognizing an object involves more than just visual analyses; its meaning must also be decoded. Extensive research has shown that processing the visual properties of objects relies on a hierarchically organized stream in ventral occipitotemporal cortex, with increasingly more complex visual features being coded from posterior to anterior sites culminating in the perirhinal cortex (PRC) in the anteromedial temporal lobe (aMTL). The neurobiological principles of the conceptual analysis of objects remain more controversial. Much research has focused on two neural regions-the fusiform gyrus and aMTL, both of which show semantic category differences, but of different types. fMRI studies show category differentiation in the fusiform gyrus, based on clusters of semantically similar objects, whereas category-specific deficits, specifically for living things, are associated with damage to the aMTL. These category-specific deficits for living things have been attributed to problems in differentiating between highly similar objects, a process that involves the PRC. To determine whether the PRC and the fusiform gyri contribute to different aspects of an object's meaning, with differentiation between confusable objects in the PRC and categorization based on object similarity in the fusiform, we carried out an fMRI study of object processing based on a feature-based model that characterizes the degree of semantic similarity and difference between objects and object categories. Participants saw 388 objects for which feature statistic information was available and named the objects at the basic level while undergoing fMRI scanning. After controlling for the effects of visual information, we found that feature statistics that capture similarity between objects formed category clusters in fusiform gyri, such that objects with many shared features (typical of living things) were associated with activity in the lateral fusiform gyri whereas objects with fewer shared features (typical of nonliving things) were associated with activity in the medial fusiform gyri. Significantly, a feature statistic reflecting differentiation between highly similar objects, enabling object-specific representations, was associated with bilateral PRC activity. These results confirm that the statistical characteristics of conceptual object features are coded in the ventral stream, supporting a conceptual feature-based hierarchy, and integrating disparate findings of category responses in fusiform gyri and category deficits in aMTL into a unifying neurocognitive framework.

Description

Keywords

Adult, Brain Mapping, Female, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Names, Oxygen, Pattern Recognition, Visual, Reaction Time, Recognition, Psychology, Visual Cortex, Visual Pathways, Young Adult

Journal Title

J Cogn Neurosci

Conference Name

Journal ISSN

0898-929X
1530-8898

Volume Title

Publisher

MIT Press - Journals
Sponsorship
Medical Research Council (G0500842)
Medical Research Council (G19/27)
European Research Council (249640)
British Academy (LRG-39870)
This work was supported by a grant from the Medical Research Council (G0500842) to L. K. T., a British Academy (Grant Number LRG-45583) grant to L. K. T. and K. I. T., a Newton Trust grant to L. K. T. and K. I. T., the European Research Council (ERC) under the European Community ʼs Seventh Framework Programme (FP7/2007 – 2013)/ERC (Grant Agreement Number 249640) to L. K. T., and a Swiss National Science Foundation Ambizione Fellowship (Grant Number PZ00P1_126493) to K. I. T.