Influence of dendritic morphology on axonal competition

The development of nerve connections involves competition among axons for survival promoting factors, or neurotrophins, which are released by the axons' target cells. To study the influence of the target's dendritic tree on axonal competition, the authors have extended their previous model of axonal competition (1999) to take into account the extracellular space around the dendrites. The authors show that spatial separation of innervating axons on the target's dendrites mitigates competition and permits the coexistence of axons. The model accounts for the finding that in many types of neurons a positive correlation exists between the size of the dendritic tree and the number of impinging innervating axons surviving into adulthood. Their results emphasize the importance of postsynaptic dendritic morphology in the development of specific patterns of nerve connections, on which the function of the nervous system depends.