The relationship between corpus callosum size and forebrain volume

Abstract

Using high-resolution in vivo magnetic resonance morphometry we measured forebrain volume (FBV), midsagittal size of the corpus callosum (CC) and four CC subareas in 120 young and healthy adults (49 women, 71 men). We found moderate linear and quadratic correlations, indicating that the CC and all CC subareas increase with FBV both in men and women (multiple r2 ranging from 0.10 to 0.28). Allometric equations revealed that these increases were less than proportional to FBV (r2 ranging from 0.02 to 0.30). Absolute CC measurements, as well as CC subareas relative to total CC or FBV (the latter measures termed the CC ratios), were further analyzed with regard to possible effects of handedness, gender, or handedness by gender interaction. Contrary to previous reports, left-handers did not show larger CC measurements compared to right-handers. The only apparent influence of gender was on the CC ratios, which were larger in women. However, smaller brains had larger CC ratios which were mainly independent of gender, a result of the less than proportional increase of callosal size with FBV. We suggest that the previously described gender differences in CC anatomy may be better explained by an underlying effect of brain size, with larger brains having relatively smaller callosa. This lends empirical support to the hypothesis that brain size may be an important factor influencing interhemispheric connectivity and lateralization.

Structural changes of the corpus callosum in tinnitus

“…The CC is smaller in smaller brains (Jancke et al, 1997). More specifically, a smaller auditory cortex presumably gives rise to a smaller number of callosal fibers crossing to the contralateral side.…”

Evaluation of Callosal Motor Fiber Location in the Human Brain by Diffusion Tensor Tractography Combined with Functional MRI

“…This result indicats that foot CMFs are generally located in the posterior part of the CC, occupying approximately one-third of its portion. In a previous study, Jancke et al showed that the distance ratio of the isthmus was generally located in 20-33.3% of the posterior portion of the CC, based on dividing the length of the structure into three equal portions, namely, the anterior third, middle third, and posterior third, including the isthmus and splenium 9) . Based on this result, we attempted to identify a more detailed relative anatomical location within the isthmus, which is located in the posterior third portion of the CC.…”

“…Many studies have investigated the anatomical and functional characteristic of the CC in humans 2,7,9,10,13,16,18,25) . These studies investigated the thickness, volume, and area information of the CC to provide accurate anatomical information 9,10,25) .…”

“…These studies investigated the thickness, volume, and area information of the CC to provide accurate anatomical information 9,10,25) . Moreover, studies have compared the distribution of the CC in both healthy and diseased individuals in order to provide information regarding anatomical changes in diseased individuals 1,11,26) .…”

“…Being the largest fiber bundle, it enables interconnection between the two cerebral hemispheres [1][2][3][4][5][6][7][8] . Previous studies have used magnetic resonance imaging (MRI) to determine several anatomical and morphological attributes of the CC, such as volume, gender difference, and handedness for the evaluation of changes between health and neurological disorders 1,4,6,[9][10][11][12] . The anatomical location and features of CC-related motor fibers, known as callosal motor fibers (CMFs), have been studied by many neurological researchers to assess and obtain more accurate characteristic information about the CC 2,7,[13][14][15] .…”