The impact of different modes of neuronal migration on brain evolution
García-Moreno F., Molnár Z.
Most neurons in the central nervous system assemble to circuits and function in a location that is different from their site of origin. Neuronal migration has strong implications in brain development, and the way the migratory patterns evolved brought major consequences on brain evolution. Here, we review the impact that the two main modes neuronal migration had on vertebrate brain diversity and function. First, radial migration enabled a more efficient production of neurons from the limited proliferative sector and promoted the efficient rearrangement of internal circuits. And second, tangential migration influenced brain evolution at several levels, such as diversifying neuronal types, enhancing network computational capabilities, shifting developmental programs on distant regions, and promoting novel wiring scenarios. We review the evolving modes of neuronal migration that sculpted and diversified vertebrate brains and how they substantially increased brain complexity over vertebrate evolution.