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Updated: Jun 19, 2026
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A MRI-Based Toolbox for Neurosurgical Planning in Nonhuman Primates
Published on: July 17, 2020
Evolution amplified processing with temporally dispersed slow neuronal connectivity in primates
Roberto Caminiti1, Hassan Ghaziri, Ralf Galuske
1Department of Physiology and Pharmacology, University of Rome La Sapienza, 00185 Rome Italy.
Summary
The corpus callosum (CC) facilitates brain hemisphere communication via axons. Axon size and brain size evolution impact interhemispheric communication delays, affecting cortical dynamics.
Area of Science:
- Neuroscience
- Comparative Anatomy
- Brain Connectivity
Background:
- The corpus callosum (CC) is the primary interhemispheric communication pathway.
- Axon size varies within the CC, connecting specific cortical regions.
- Previous research has not fully detailed evolutionary changes in CC axon properties and their impact on conduction delays.
Purpose of the Study:
- To investigate the relationship between axon diameter, conduction velocity, and brain size across species.
- To quantify changes in CC axon composition and conduction delays from macaques to humans.
- To explore the functional consequences of altered interhemispheric communication delays on cortical dynamics.
Main Methods:
- Comparative analysis of corpus callosum (CC) axon morphology across macaque, chimpanzee, and human brains.
- Estimation of conduction velocities based on axon diameter.
- Modeling of interhemispheric conduction delays considering connection length and velocity.
Main Results:
- Axon diameter and conduction velocity increase slightly from macaques to chimpanzees due to more large axons.
- Axon diameter and conduction velocity do not significantly increase between chimpanzees and humans.
- Interhemispheric conduction delays double from macaques to humans, with a threefold increase in delay range.
Conclusions:
- Evolutionary increases in brain size, not just axon diameter, significantly lengthen interhemispheric communication times.
- Altered conduction delays may profoundly influence the dynamics of interhemispheric oscillators and overall cortical function.
- Understanding these changes is crucial for comprehending species-specific cognitive processes.
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