In neuroanatomy, the central sulcus (also central fissure, fissure of Rolando, or Rolandic fissure, after Luigi Rolando) is a sulcus, or groove, in the cerebral cortex in the brains of vertebrates. It is sometimes confused with the longitudinal fissure.
The central sulcus is a prominent landmark of the brain, separating the parietal lobe from the frontal lobe and the primary motor cortex from the primary somatosensory cortex.
Evolution of the central sulcus
The evolution of the central sulcus is theorized to have occurred in mammals when the complete dissociation of the original somatosensory cortex from its mirror duplicate developed in placental mammals such as primates, though the development did not stop there as time progressed the distinction between the two cortices grew.
Evolution in primates
The central sulcus is more prominent in apes as a result of fine-tuning of the motor system in apes.
Previous studies have also shown that the location where the split in the central sulcus occurs is at the division point between the wrist and the individual digits in primary motor cortex, further implicating the relation between the development of this region through the use of their digits. It begins as a point or groove in the parasagittal region of the brain. It then becomes a distinct invagination that lengthens towards the lateral sulcus and towards the longitudinal fissure at approximately 22 to 23 weeks of gestational age.
Between 2 and 3 years of age, the landmark ‘Pli de Passage Frontoparietal Moyen’ (PPFM), which is a depression buried at the central part of the central sulcus, begins to appear. At 3 years of age, the average depth curve of the central sulcus is similar to that of adults.
Influences on development
The development of the shape of the central sulcus is influenced by both genetic and non-genetic factors. The deep structure of the central sulcus has been found to be more consistent in different brains than its superficial structure, suggesting that the superficial structure is more susceptible to non-genetic factors.
The shape of the central sulcus has been found to be different between people of different biological sex. Those of male biological sex have been found to have a less convoluted (small fractal dimension) right anterior wall of the central sulcus. In addition, while the width of the central sulcus varies, the central sulcus of males has shown to have a larger average width than the central sulcus of females. However, this is specific to the right hemisphere since the central sulcus of the left hemisphere has not shown significant results regarding gender differences. With regard to gender differences between hemispheres, females have been shown to have a larger average width of the central sulcus on the left side compared to that of the central sulcus on the right side.
As motor functions develop, it is expected that the shape of the central sulcus will change. This is due to the role of the central sulcus in separating the primary motor cortex and primary somatosensory cortex. Among musicians who specialize in string instruments, this omega formation is specific to the right central sulcus. However, among pianists, this omega formation occurs on both sides but more prominently on the left side.
Clinical significance
Attention deficit hyperactivity disorder
Attention deficit hyperactivity disorder (ADHD) has been associated with sensorimotor deficits and the central sulcus divides both somatosensory and primary motor areas prompting research into how the shape of the central sulcus and ADHD may alter brain development in these individuals. The cortical thickness and average and maximum depth of the central sulcus has been shown to be larger for ADHD individuals when compared to normal individuals. The foreshortening of the central sulcus has been found to be an abnormality associated with this syndrome. However, the severity of the disability has been found to not be fully dependent upon the morphology of the central sulcus.