The relationship between corpus callosum size and forebrain volume

Area of Science:

• Neuroscience
• Human Anatomy
• Brain Imaging

Background:

• The corpus callosum (CC) facilitates interhemispheric communication.
• Previous studies suggest gender and handedness influence CC anatomy.
• The relationship between CC size, forebrain volume (FBV), and individual differences requires further investigation.

Purpose of the Study:

• To investigate the relationship between forebrain volume (FBV) and corpus callosum (CC) size and its subregions in healthy adults.
• To examine the influence of gender and handedness on CC morphometry.
• To test the hypothesis that brain size, rather than gender, underlies observed differences in CC anatomy.

Main Methods:

• High-resolution in vivo magnetic resonance morphometry was used to measure FBV and CC dimensions in 120 healthy adults.
• Statistical analyses included correlation, allometric equations, and examination of CC ratios relative to FBV.
• Effects of handedness, gender, and their interaction were analyzed.

Main Results:

• Moderate positive correlations were found between FBV and CC size, with CC growth being less than proportional to FBV.
• Contrary to prior research, no significant differences in absolute CC measurements were found between left-handers and right-handers.
• Women exhibited larger CC ratios (CC size relative to FBV), but this was primarily linked to smaller brain size, not gender itself.

Conclusions:

• The less than proportional increase of CC size with FBV explains why smaller brains have relatively larger callosal measurements.
• Observed gender differences in CC anatomy may be attributable to underlying variations in brain size.
• Brain size is a significant factor influencing interhemispheric connectivity and brain lateralization.