Complex sentence: Mutation of Tbr-1 results in expression of Fezf2 in layer VI and malformation of the corticospinal tract while abnormal activation of Tbr-1 in layer V eliminates corticospinal tract formation.
Split into simpler sentences: Mutation of Tbr-1 results in Fezf2 expression in layer VI and malformation of the corticospinal tract. Abnormal activation of Tbr-1 in layer V eliminates corticospinal tract formation.