During fetal development of the mammalian brain, the
cerebral cortex undergoes a marked expansion in surface area in some species,
which is accommodated by folding of the tissue in species with most expanded
neuron numbers and surface area. Researchers have now identified a key
regulator of this crucial process.
Different regions of the mammalian brain are devoted to the
performance of specific tasks. This in turn imposes particular demands on their
development and structural organization. In the vertebrate forebrain, for
instance, the cerebral cortex – which is responsible for cognitive functions –
is remarkably expanded and extensively folded exclusively in mammalian species.