My research examines how the development of the cerebral cortex is altered in two developmental disorders, Down syndrome and Fragile X syndrome, which are characterized by mental impairment.   The cerebral cortex is the most complex area of the brain and is responsible for functions unique to humans, such as language and abstract thought.  Problems in any of the crucial steps in the formation of the cerebral cortex can lead to mental impairment.  The causes of both Down syndrome and Fragile X syndrome are genetic. Down syndrome is caused by an extra chromosome (Trisomy 21), while Fragile X syndrome is due to a single gene mutation (fmr1 gene).  I am using human neural progenitor cells that carry either trisomy 21 or the fmr1 mutation to study the development of the cerebral cortex in vitro.  Human neural progenitor cells have intrinsic characteristics that can be investigated in culture to further our understanding and treatment of developmental disorders.  By defining the aberrant neurodevelopmental steps that lead to mental retardation, we may be able to target therapeutics for these developmental disorders.