The neocortex is the outer layer of the cerebral hemispheres, where in humans, is believed to be involved in higher functions such as language, conscious thought, sensory perceptions, etc. There has been a high volume of interest and debate among developmental neurobiologists regarding the molecular mechanisms/molecules involved in differentiation and development of the neocortex. But to start with, the question is, why specifically this region of the brain?
The neocortex is not known to be present throughout the animal kingdom, but is presumed to be specific to mammals. For example, we, humans, are able to perform particular functions and have a higher order of thinking due to the mechanisms/processes of the neocortex. Therefore, the unknown entities and development of the neocortex is a highly talked about subject within this field because it can help explain the evolution of human behavior and the known generates high interest as many researchers seek answers about the development of mankind.
Therefore, within the past 20 years, there has been significant progress in identifying certain patterning of the neocortex through state-of-the-art molecular approaches, however, we are still very far from knowing the complete truth. For example, we now know that the anterior-posterior orientation has a genetic impact that if altered, can lead to diseases such as smooth brain syndrome. In this case it is the alterations of the concentration gradients of two molecules, DCX anteriorly and LIS1 posteriorly. Additionally, there is now pertinent evidence of genetic patterning that is symmetric between the two hemispheres, that if altered, can also lead to severe phenotypes. Another concept at large debate is whether the differentiation and development of the neocortex is more dependent on intrinsic or extrinsic mechanisms, in which informs our understanding on the developmental plasticity phenomena, critiquing the importance of critical and sensitive periods. In other words, how much is the regionalization of areas in the neocortex affected by varying the levels of essential transcription factors?
Besides the uses of molecular techniques, Chen and his colleagues are investigating these questions through a combination of twin studies and structural MRI to demonstrate the relative contributions of genetic and environmental factors in regionalization of the cerebral cortex. Therefore, they have concluded that although "genetic factors may have a boisterous influence in the establishment of regionalization of the cortex, functional areas do not seem to be influenced by the same factors," implementing that those environmental factors can also play a significant role in neuro-development.
With the newly employed combination of these analytical studies and ultimate hype on the development of the neocortex, this marks an exciting new chapter on the study of human brain development, where we can hopefully determine the genetic and environmental factors that determine the higher order functions of human/mammalian brain. Furthermore, with this marked data and more advanced research on the human brain development to come, we may one day find more genetic or environmental patterning of the brain that can lead to cures of diseases that are defined as incurable today.
Schlagger, B. "Mapping Genetic Influences On Cortical Regionalization." Neuron. Volume 74, Issue 4. Pg. 499-501. 17 November 2011.