The human pattern of gyrification in the cerebral cortex

Area of Science:

• Neuroscience
• Comparative Anatomy
• Primatology

Background:

• Cortical folding, quantified by the gyrification index (GI), is a key feature of mammalian brain evolution.
• Understanding variations in GI across species and within brain regions is crucial for evolutionary and developmental neuroscience.

Purpose of the Study:

• To analyze the gyrification index (GI) in adult human brains.
• To investigate correlations between GI and various biological parameters.
• To compare human brain gyrification patterns with those of non-human primates.

Main Methods:

• Calculation of the gyrification index (GI) for whole brains and specific regions.
• Correlation analyses with age, body measurements, and brain metrics.
• Comparative analysis of GI patterns between humans, prosimians, and Old World monkeys.

Main Results:

• No significant correlations were found between GI and age, body weight, body length, brain weight, or prosencephalon/cortex volume.
• GI did not differ significantly between sexes, hemispheres, or specific temporal plane sides.
• Maximal GI values were observed in the prefrontal and parieto-temporo-occipital association cortices.
• Human brains exhibited the largest differences in GI patterns compared to other primates, especially in the prefrontal cortex.
• Mean GI increased from prosimians to humans, with pongids showing the highest values among non-human primates.

Conclusions:

• The gyrification index (GI) is a robust measure for analyzing cortical folding in human and primate brains.
• Human brain gyrification shows distinct regional patterns, particularly in the prefrontal cortex, differentiating it from other primates.
• Evolutionary trends indicate an increase in mean GI from lower primates to humans.