Evolution of the motor cortex microstructure and its lateralization: a comparative study of chimpanzees and humans
Human hand coordination exceeds that of other species, including great apes, and is marked by pronounced right-hand dominance. This specialization parallels an expansion of its cortical representation, forming the hand-knob in the motor cortex. In humans, this region shows high myelination on quantitative MRI (qMRI), but whether this feature is shared with great apes remains unclear. It is also…
The motor cortex plays a crucial role in human hand coordination, which surpasses that of other species, such as great apes. This specialization is evident in the pronounced right-hand dominance observed in humans. This human trait is mirrored by an expansion of the cortical representation for hand movement, forming what is known as the "hand-knob" in the motor cortex.
The high myelination of this region in humans, as revealed through quantitative MRI (qMRI), raises questions about whether this feature is also present in great apes. Additionally, it is uncertain if the increased right-hand dominance in humans is accompanied by a greater hemispheric asymmetry in the motor cortex's microstructure.
Utilizing high-resolution qMRI, researchers compared motor cortex subdivisions responsible for controlling the leg, hand, and face in both humans and chimpanzees. The findings revealed consistently higher myelin and iron content in the hand-knob region for both species, indicating a conserved evolutionary role. However, the study also uncovered that only humans exhibited enhanced rightward lateralization.
These results shed light on both the conserved and species-specific characteristics of the motor cortex, providing valuable insights into the evolution of manual dexterity and handedness.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
