Human corpus callosum: a stable mathematical model of regional neuroanatomy.

The functional utility of regional parameters of the corpus callosum (CC) derived from factor analysis has been demonstrated in the rat and the human. In this study, we have utilized factor analysis to compare CC structure between two independent groups of human subjects. Tracings of the CC were taken from the midsagittal MRIs of two human samples consisting of 103 healthy volunteers and 146 neurological patients. CCs were digitized and factor analyses were performed on 99 widths, area, axis length, and perimeter. The factor structures of these two data sets were highly congruent except that one factor analysis yielded a seven-factor solution, whereas the factor analysis of the other subject population gave six factors. Further study determined that the six-factor structure could be attributed to the presence of non-consistent right-handed males whose wider CCs in the isthmus region biased the correlations. When CC parameters of consistent and non-consistent right-handed subjects were standardized, a seven-factor structure resulted. Reproducibility of the factor structure indicates that there are shared neuroanatomical characteristics of CC morphology among two disparate populations of humans in spite of variability in CC size due to sex, age, hand preference, and hand consistency.