Interhemispheric asymmetries of the modular structure in human temporal cortex

Language-relevant processing of auditory signals is Lateralized and involve the posterior part of Brodmann area 22. We found that the functional Later alization in this area was accompanied by interhemispheric differences in t he organization of the intrinsic: microcircuitry. Neuronal tract tracing re vealed a modular network of long-range intrinsic connections Linking regula rly spaced clusters of neurons. Although the cluster diameter was similar i n both hemispheres, their spacing was about 20 percent Larger in the Left h emisphere. Assuming similar relations between functional and anatomical arc hitecture as in visual cortex, the present data suggest that more functiona lly distinct columnar systems are included per surface unit in the Left tha n in the right area 22.