Changes in the structure of gyri in the cerebral cortex are associated with various diseases and disorders. Pachygyria, lissencephaly, and polymicrogyria are all the results of abnormal cell migration associated with a disorganized cellular architecture, failure to form six layers of cortical neurons (a four-layer cortex is common), and functional problems. The abnormal formation is commonly associated with epilepsy and mental dysfunctions. Pachygyria (meaning "thick" or "fat" gyri) is a congenital malformation of the cerebral hemisphere, resulting in unusually thick gyri in the cerebral cortex. Pachygyria is used to describe brain characteristics in association with several neuronal migration disorders; most commonly relating to lissencephaly. Lissencephaly (smooth brain) is a rare congenital brain malformation caused by defective neuronal migration during the 12th to 24th weeks of fetal gestation resulting in a lack of development of gyri and sulci. Polymicrogyria (meaning "many small gyri") is a developmental malformation of the human brain characterized by excessive folding of the gyri and a thickening of the cerebral cortex. It may be generalized, affecting the whole surface of the cerebral cortex or may be focal, affecting only parts of the surface. Polymicrogyria may be caused by mutations within several genes, including ion channels.
Gyrus
Microgyrus
Choroid
Tophus
Canthus
Ateronon
Lockets
Orbital septum