GDPs are slowly spreading in brain structures with a speed of approximately 1 mm/s. They use neuron's connection (axons) for this, using these connections they can develop in connected structures as well (from example from retina to geniculate nucleus).
According to current point of view, slow developing GDPs are essential for neural nets of immature brain development. It's supposed that GDPs take the closest part in synaptogenesys, modification of synaptic connections and synapses maturation.
Origin and properties
One of the main conditions for GDPs development (that are met in premature brain and that aren't take place in adult one) is that GABA action on these stages should be inhibitory rather then exitatory. This, in its turn, is caused by a much higher concentration of Cl- concentration in cells cytoplasm.