Functional MRI Study for Phonological and Semantic Language Processing in Strongly Right-Handed Korean Twenty Year Olds

Lee, Dong Yeob; Chung, Chun Kee; Kim, June Sic; Kang, Eunjoo; Song, In Chan

Abstract

OBJECTIVE
Using functional magnetic resonance imaging, cerebral language areas were determined during a series of language tasks in normal strong right-handed subjects.
METHODS
Twelve normal right-handed volunteers were examined on a 1.5T MR unit. Language task paradigms included two phonological tasks involving meaningless letters and sentences, and four semantic tasks using different types of words. Each language task was examined using a separate scan consisted of three blocks separated by rest periods. BOLD (blood oxygenation level dependent) signals during language tasks were compared using 24 sec alternating rest periods during which subjects concentrated on a plus symbol. After preprocessing and statistically analyzing individual data, group analysis (p<0.001, k=50) was performed using SPM99 software.
RESULTS
Meaningless letter reading was more efficient than sentence reading, in terms of delineating brain regions related to phonological processing, we found significant regions in the left inferior frontal gyrus (IFG), left thalamus, bilateral cingulate gyri, right anterior superior temporal gyrus (STG), right IFG, and left inferior parietal lobule (IPL). During semantic tasks, left IFG, left posterior middle temporal gyrus, left IPL, bilateral medial frontal gyrus, right posterior STG, right parahippocampal, and fusiform gyri were found to be activated.
CONCLUSION
During the two phonological tasks, normal strongly right-handed people more actively used the left IFG, right anterior temporal lobe, and right IFG than during semantic processing, whereas during the four semantic tasks, these subjects more actively used the bilateral posterior temporal and right medial temporal lobes.