Neural Migration

• New neurons move in wave like fashion to their correct position in the cerebral hemispheres 
• A chemical reeling signals neurons where to stop 
• At about 20 weeks GA, process stops and 6 layers of the cerebral cortex are established 

Neural Migration Defects 

• Schizencephaly: clefts in the cerebral hemispheres
• Lissencephaly: smooth brain that lacks characteristic sulci and gyri
• Both conditions due to lack of reelin leading to a failure of neurons to migrate to props