Priming for letters and pseudoletters in mid-fusiform cortex: examining letter selectivity and case invariance.
A large body of research indicates a critical role for the left mid-fusiform cortex in reading, however, the extent to which this area is dedicated exclusively to the processing of words and letters has been debated. Two questions regarding left mid-fusiform function are critical to this debate: (1) Are letters stored preferentially compared to visually equivalent non-letters (letter selectivity)? (2) Are letter representations abstract with respect to changes in letter case (e.g., A/a; case invariance)? The present study addressed these questions by comparing priming for letters and pseudoletters in left and right mid-fusiform regions using functional magnetic resonance imaging while subjects performed a same/different matching task. Results revealed priming for letters but not pseudoletters in the left mid-fusiform region, suggesting that representations are letter selective. However, no priming for different-case-primed letters was observed in this region, indicating that representations are not case invariant. In addition, priming for pseudoletters but not letters was observed in the homologous right mid-fusiform region. Overall, findings contradict strongly modular theories of letter/word processing and suggest that left and right mid-fusiform regions support generic object processes that are differentially effective for representing disparate types of visual stimuli.
Burgund
E Darcy
ED
Rice University, Houston, TX 77251, USA. dburgund@rice.edu
Guo
Yi
Y
Aurbach
Elyse L
EL
D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D011578:Psycholinguistics; D011930:Reaction Time; D011932:Reading; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000502:physiology*; D055815:Young Adult