Action potential
The formation of these arbors is regulated by the strength of local signals during development. Several patterns in activity control the development of the brain. Action potential changes in the retina, hippocampus, cortex, and spinal cord provide activity-based signals both to the active neurons and their post-synaptic target cells. Spontaneous activity originating within neuronal gap junctions, the cortex sub-plate, and sensory inputs are all involved in the cell signaling that regulates dendrite growth.