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. ==Notable gyri==