The most striking, yet poorly understood morphological features of the human cerebral cortex are the complex arrangements of its foldings: the sulci and gyri. Cortical gyrification is formed during fetal age and childhood. Thus, indices measuring the folding pattern could provide cues for the neurodevelopmental pathopsychology.

A fully-automated method was applied to T1 magnetic resonance images to extract, label and measure the sulcus area in the whole cortex. Gyrification was assessed using both global and local sulcal indices, defined respectively as the ratio between the total sulcal area, or the area of each labeled sulcus, and the outer cortex area.

As a validation, MRI datasets in controls showed that handedness modify the folding of the motor area in dominant hemisphere (Mangin 2004), and differences in left and right superior temporal sulci which may stem from language-based asymmetries (Ochiai 2004). In a sample of schizophrenia patients with treatment-resistant auditory hallucination, global sulcal surface index was decreased, and local sulci surface indices differed in language-related regions. Further analyses are performed in samples from various MR datasets. Statistics on such measurements should generalize across patients and hospitals.

The potential of the gyrification pattern for the neuroimage-based inference of developmental deviation will be examined.