Sheng He - US grants

The human visual system has tremendous capabilities for processing a complex world. For literate people, such expertise includes extremely efficient processing of written script. How does the visual system achieve this goal? One hypothesis is that an area in the mid-fusiform cortex, often called the Visual Word Form Area (VWFA), plays an important role in processing visual words. However, the level of functional selectivity of VWFA remains controversial, as well as its learning capacity (plasticity). With the support from the National Science Foundation, Dr. Sheng He and colleagues at the University of Minnesota, in collaboration with colleagues in China (Chinese Academy of Sciences, Chinese University of Hong Kong, and Huaxi hospital in Chengdu), will investigate the specific functional selectivity of VWFA, especially in terms of its role in processing Chinese characters. The project will be able to obtain information at very fine spatial scales using high field functional magnetic resonance imaging (fMRI) scanners. Fast dynamical information will be obtained using magnetoencephalography (MEG) and electroencephalography (EEG). Advanced data analysis methods will be used to extract more information from the brain imaging data than has previously been possible. The completion of this research project will result in a comprehensive understanding of the properties of the mid-fusiform region. Through close collaboration with colleagues in China, this project will also have the unique opportunity to track the potential change of functional properties of the mid-fusiform region in native Chinese illiterate participants as they are taught to read. Results from illiterate adults learning to read Chinese will be compared to results from native English speakers learning Chinese. This comparison will help determine whether extensive visual experience in adulthood is sufficient for the development of a functional specialization in the brain, or if early exposure is critical.

Detailed understanding of the specific functional selectivity and plasticity of this early brain area related to reading will contribute to the formulation of scientifically sound educational strategies. Because the project will explore the extent of plasticity in the adult reading brain, it will provide guidance to the strategies and policies regarding the alleviation of adult illiteracy. It could also contribute to better rehabilitation procedures and processes for people who suffer from reading disabilities due to brain damage. The use of multiple advanced brain imaging techniques will provide excellent training opportunities to both graduate students and undergraduate students. The collaboration between scientists in the US and China will facilitate long-term communication on many fronts and promote an exchange of ideas between the scientists of these two countries.

Our long-term goal is to understand how humans perform natural tasks given realistic visual input. Object perception is critical for the everyday tasks of recognition, planning, and motor actions. Through vision, we infer intrinsic properties of objects, including their shapes, sizes, materials, as well as their identities. We also infer their depths and movement relationships to each other and ourselves, as well as determine how to use this information. The remarkable fact is that the human visual system provides a high level of functionality despite complex and objectively ambiguous retinal input. Current machine vision systems do not come close to normal human visual competence. In contrast, our daily visual judgments are unambiguous, and our actions are reliable. How is this accomplished? Our conceptual approach to this question is motivated by our previous work on object perception as Bayesian statistical inference, and its implications for how human perception gathers and integrates information about scenes and objects to reduce uncertainty, resolve ambiguity and achieve action goals. Our experimental approach to this question grows out of our team's past accomplishments in using behavioral techniques such as interocular suppression, high-field functional magnetic resonance imaging and analysis, and Bayesian observer analysis of human behavioral performance. We combine our conceptual and experimental approaches to address a new set of questions. In three series of experiments, we aim to better understand: 1) the relationship between cortical activity and the perceptual organization of image features into unambiguous object properties and structures (Within-object interactions);2) how visual information about other objects and surfaces reduces uncertainty about the representation of an object's properties and depth relations (Between-object interactions);and 3) whether and how information and uncertainty may be processed differently depending on the viewer-object interactions demanded by task, as predicted by theory (Viewer-object interactions).