Publications from 2002

Booth JR, Burman DD, Meyer JR, Gitelman DR, Parrish TB & Mesulam MM (2002). Modality independence of word comprehension. Human Brain Mapping, 16, 251-261. [pdf]

Functional magnetic resonance imaging (fMRI) was used to examine the functional anatomy of word comprehension in the auditory and visual modalities of presentation. We asked our subjects to determine if word pairs were semantically associated (e.g., table, chair) and compared this to a reference task where they were asked to judge whether word pairs rhymed (e.g., bank, tank). This comparison showed task-specific and modality-independent activation for semantic processing in the heteromodal cortices of the left inferior frontal gyrus (BA 46, 47) and left middle temporal gyrus (BA 21). There were also modality-specific activations in the fusiform gyrus (BA 37) for written words and in the superior temporal gyrus (BA 22) for spoken words. Our findings are consistent with the hypothesis that word form recognition (lexical encoding) occurs in unimodal cortices and that heteromodal brain regions in the anterior as well as posterior components of the language network subserve word comprehension (semantic decoding).

Booth JR, Burman DD, Meyer JR, Gitelman DR, Parrish TB & Mesulam MM (2002). Functional anatomy of intra- and cross-modal lexical tasks. Neuroimage, 16, 7-22. [pdf]

Functional magnetic resonance imaging (fMRI) was used to examine lexical processing in normal adults (20-35 years). Two tasks required only intra-modal processing (spelling judgments with visual input and rhyming judgments with auditory input) and two tasks required cross-modal processing between phonologic and orthographic representations (spelling judgments with auditory input and rhyming judgments with visual input). Each task led to greater activation in the unimodal association area concordant with the modality of input, namely fusiform gyrus (BA 19, 37) for written words and superior temporal gyrus (BA 22, 42) for spoken words. Cross-modal tasks generated greater activation in posterior heteromodal regions including the supramarginal and angular gyri (BA 40, 39). Cross-modal tasks generated additional activation in unimodal areas representing the target of conversion, superior temporal gyrus for visual rhyming and fusiform gyrus for auditory spelling. Our findings suggest that the fusiform gyrus processes orthographic word forms, the superior temporal gyrus processes phonologic word forms, and posterior heteromodal regions are involved in the conversion between orthography and phonology.

Booth JR, Perfetti CA (2002). Onset and rime structure influences naming but not early word identification in children and adults. Scientific Studies of Reading, 6, 1-23. [pdf]

Four experiments assessed the role of the onset-rime structure in visual word recognition. If the onset-rime structure is important for recognition, then primes or masks with 2 overlapping letters at the beginning or at the end of 4-letter words should facilitate recognition of consonant-vowel (CV) CCVC-structure words more than the recognition of CVCC words. Using the brief identification paradigm to tap into early word identification processes (14-56 msec), Exps 1 through 3 (n=168--combined Ss for Exps 1-3) showed no evidence for the importance of onset-rime in children (2nd through 6th graders) or adults. However, these experiments show that end masks produced higher identification accuracy than begin masks, suggesting that early word identification involves a serial component. Exp 4 (n=135) with adults replicated the effects of J. A. Bowey (1990) by showing that onset-rime structure is important in oral reading. Begin and end primes facilitated the naming of CCVC words more than CVCC words, suggesting that the onset-rime structure may be an important unit in phonologic output. The begin, end, and control masks or rimes for the CCVC and CVCC target words sorted alphabetically are appended.