Interactions between brain structure and behavior: The corpus callosum and bimanual coordination

• The corpus callosum and bimanual coordination show a powerful brain–behavior link.
• Clinical and in vivo diffusion tensor imaging work has reinforced this association.
• Research shifted from macro- to microstructural measures of the corpus callosum.
• Age, pathology and training mediate this brain structure–behavior association.
• Mapping of callosal subregions onto specific bimanual task types is complex.

Bimanual coordination skills are required for countless everyday activities, such as typing, preparing food, and driving. The corpus callosum (CC) is the major collection of white matter bundles connecting both hemispheres that enables the coordination between the two sides of the body. Principal evidence for this brain–behavior relationship in humans was first provided by research on callosotomy patients, showing that sectioning (parts of) the CC affected interactions between both hands directly. Later, new noninvasive in vivo imaging techniques, such as diffusion tensor imaging, have energized the study of the link between microstructural properties of the CC and bimanual performance in normal volunteers. Here we discuss the principal factors (such as age, pathology and training) that mediate the relationship between specific bimanual functions and distinct anatomical CC subdivisions. More specifically, the question is whether different bimanual task characteristics can be mapped onto functionally distinct CC subregions. We review the current status of this mapping endeavor, and propose future perspectives to inspire research on this unique link between brain structure and behavior.