Neurotrophins and synaptic plasticity in the mammalian spinal cord

The pathway mediating the monosynaptic stretch reflex has served as an impo rtant model system fur studies of plasticity in the spinal cord. Its useful ness is extended by evidence that neurotrophins, particularly neurotrophin- 3 (NT-3), which has been shown to promote spinal axon elongation, can modul ate the efficacy of the muscle spindle-motoneurone connection both after pe ripheral nerve injury and during development. The findings summarized here emphasize the potential for neurotrophins to modify function of both damage d and undamaged neurones. It is important to recognize that these effects m ay be functionally detrimental as well as beneficial.