PLANUM TEMPORALE AND BRODMANN AREA-22 - MAGNETIC-RESONANCE-IMAGING AND HIGH-RESOLUTION POSITRON EMISSION TOMOGRAPHY DEMONSTRATE FUNCTIONAL LEFT-RIGHT ASYMMETRY

Objective: To describe the registered analysis of magnetic resonance i maging and glucose metabolic data acquired with positron emission tomo graphy to determine the relationship between structure and function of temporal lobe cortical structures between the left and right hemisphe res. Background: The dominance of the left cerebral hemisphere is asso ciated with a preponderance of the left planum temporale. Subjects and Methods: Fifteen subjects without signs or symptoms of a neurological disorder. Three-dimensional-registered magnetic resonance imaging and positron emission tomography with the use of fludeoxy-glucose F18 and a high-resolution positron emission tomography scanner. Analysis of r egional metabolic activation during single-word repetition on matched parasagittal magnetic resonance imaging and positron emission tomograp hy. Results: The planum temporale was bilaterally activated without le ft-right asymmetry. The metabolic increase was asymmetric within the l eft Brodmann's area (BA) 22. The part of the left BA 22 that was burie d in the superior temporal sulcus was significantly less activated tha n the part of BA 22 on the surface of the superior temporal gyrus. The metabolic activation in the sulcal part of the left BA 22 had a signi ficant inverse correlation with the anatomical predominance of the lef t planum temporale (r=.71, P=.003) and a significant direct correlatio n with the metabolic activation in the surface aspects of the right BA 22 (r=.82, P<.001). Conclusion: Brodmann's area 22 is a critical feat ure of language dominance and is also important with regard to the exc hange of information between the two hemispheres.