Local axon guidance in cerebral cortex and thalamus: are we there yet?

Normal brain function requires the development of precise connections between thalamus and cerebral cortex. In this issue of Neuron, Cang et al. and Tori and Levitt argue that EphA/ephrin-A signaling in the target tissue guides sensory thalamic axons to the correct cortical area, and sensory cortical axons to precise thalamic targets. Although EphA/ephrin-A signaling organizes sensory maps within areas, and thalamocortical axons in the internal capsule, both papers argue that each developmental event is dissociable from the others.