CEREBRAL NETWORKS AND FUNCTIONAL BRAIN ASYMMETRY - EVIDENCE FROM REGIONAL METABOLIC CHANGES DURING WORD REPETITION

Word repetition causes a significant bilateral metabolic increase in b oth superior temporal cortices. Frontal speech areas are less activate d despite then presumable speech competence. We investigated in this s tudy the relationship between frontal and temporal cortical areas duri ng word repetition. We measured regional cerebral metabolic rates of g lucose (CMRGI) in 15 normal subjects with positron emission tomography (PET) at rest and during word repetition. Significant correlations co nnected frontal and temporal areas of both hemispheres, notwithstandin g their different levels of mean metabolic activation. The left planum temperate was a hub of significant interregional correlations, in con trast to its contralateral mate. This study indicates that an asymmetr ic network of significant connections orchestrates the speech-relevant cortical areas according to the actual needs of speech processing. (C ) 1998 Academic Press.