Tiny Variation In One Gene Led To Crucial Changes In The Human Brain
Circumvolutions and deep fissures are one of the brain’s main characteristics which increase the surface area and promotes abstract thinking and rational thinking.A team of researchers from Yale School of Medicine and Turkey have discovered the cause that led to fissures and convolutions in the evolution of the human brain – an extremely small variation of a single gene that causes the formation of these features – and have published their findings in the Nature Genetics journal on May 15.
A genetic examination of a patient in Turkey, whose brain lacked these characteristics has led to the conclusion that a deletion of two genetic letters from the human’s three bilion genetic code has lead to this transformation. Patients with similar variations (lack of deep fissures and convolutions of the brain) were also discovered with mutations in the Laminin Gamma 3 gene which is now considered to be the source of the human brain surface modifcations.
This discovery take scientists one step closer to understanding the mystery “of the crown jewel of creation” – the cerebral cortex.
The folding of the brain is one characteristic found only in mammals with larger brains like apes and dolphins, but it is best defined in humans. These characteristics increase the surface area of the cortex and facilitate complex thinking and ratiocination, with less space needed in the skull. Such fissures and convolutions are not present in small animals. Until now, despite the importance of these fissures and convolutions no scientist could be able to tell us how the human brain evolve this way. The gene responsible for these modifications is the Laminin Gamma 3 also involved in cell adhesion and embryonic developement. The Laminin Gamma 3 gene is moast active in the embryonic period, and it is crucial for the forming of dendrites which subsequently form synapses with other neurons (connection between neurons). Even though the Laminin Gamma 3 is present in other smaller mamals like mice, during the evolutin process it gained novel functions that lead to the development of fundamental features of the human occipital cortex.