Presynaptic activity induces glutamate release leading to the ...BDNF and the guidance of central axons to their targets: in vivo versus in vitro studiesRoles for neurotrophins as axon guidance molecules have been supported by evidence dating back to early observations that NGF and other members of the neurotrophin family can induce neurite outgrowth in culture (Levi-Montalcini, 1964; Davies et al