The evolutionary origin of the mammalian isocortex: Towards an
integrated developmental and functional approach Behavioral and
Brain Sciences 26 (5):535-552 (2003) |Abstract||The isocortex is
a distinctive feature of mammalian brains, which has no clear
counterpart in the cerebral hemispheres of other amniotes. This
paper speculates on the evolutionary processes giving rise to
the isocortex. As a first step, we intend to identify what
structure may be ancestral to the isocortex in the reptilian
brain. Then, it is necessary to account for the transformations
(developmental, connectional, and functional) of this ancestral
structure, which resulted in the origin of the isocortex. One
long-held perspective argues that part of the isocortex derives
from the ventral pallium of reptiles, whereas another view
proposes that the isocortex originated mostly from the dorsal
pallium. We consider that, at this point, evidence tends to
favor correspondence of the isocortex with the dorsal cortex of
reptiles. In any case, th