Building Bridges to the Cortex

Innervation of the neocortex by the thalamus is dependent on the precise coordination of spatial and temporal guidance cues. In this issue of Cell, work by López-Bendito et al. (2006) reveals that tangentially migrating cells within the ventral telencephalon are essential for axonal navigation between the thalamus and the neocortex, a process apparently mediated by Neuregulin-1/ErbB4 short- and long-range signaling.