WORD AND SHAPE SENSITIVITY IN OCCIPITO-TEMPORAL CORTEX OF ADULTS AND CHILDREN

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: Efficient extraction of shape information is essential for proficient reading. A heated debate concerns the question: is there a specialized system for processing visual word forms? We study this topic in two ways: (a) correlating fMRI signals for word processing with reading skills in children. (b) comparing fMRI visibility curves for words and other shapes such as line drawings and false fonts. Our analysis focuses on the occipito-temporal sulcus (OTS), a region hypothesized to specialize in visual word forms (Cohen et al., 2000). Methods: Nine adults (ages 23-53) and fifty children (ages 7-12) participated in four testing sessions, including neuropsychological assessment (children only), high resolution MRI, DTI and functional MRI scans. MRI scans were performed in the Lucas Center at Stanford University. In fMRI we presented visual words masked by phase-scrambled noise, while subjects were engaged in a fixation judgment task. Noise level was manipulated parametrically, resulting in 4 activation conditions, which were interleaved with fixation blocks. Adults were also presented with line drawings and false font strings in different sessions using the same paradigm. Functional data were acquired using a 3T signa GE scanner, with spiral acquisition. 26 oblique slices (3x3x3 mm), TR=2000.