Plasticity in the visual system: role of neurotrophins and electrical activity.
We report recent results concerning the action of neurotrophins on the development and plasticity of the visual system of mammals and in particular of their visual cortex. It has been demonstrated that NGF prevents all the effects of monocular deprivation during the critical period. BDNF, that in part also prevents the effects of monocular deprivation, has the interesting additional property of accelerating the development of inhibitory processes. In transgenic mice overexpressing BDNF only in the cortex, the critical period for plasticity initiates a week earlier and presents a precocious closure. Visual acuity also develops much before than in normal animals. These phenomenological observations are paralleled by a precocious increase of inhibitory synapses and inhibitory currents in pyramidal neurons. LTP, tested by stimulation of the white matter, recording in layers 2 and 3 of the visual cortex, presents modifications correlated with the alterations observed in the critical period. Last we report the finding from in vitro and in vivo experiments that MAPkase (Erg 1 and 2) is the molecular chain of events driven both by light and neurotrophins, likely at the bases of the phenomena of plasticity observed during the critical period.
Maffei
L
L
Istituto di Neuroscienze del CNR, Scuola Normale Superiore, Pisa, Italy. maffei@in.pi.cnr.it
D000818:Animals; D023882:Dominance, Ocular / Q000187:drug effects / Q000502:physiology; D006801:Humans; D051379:Mice; D009414:Nerve Growth Factors / Q000378:metabolism* / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D014793:Visual Cortex / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D014795:Visual Pathways / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism
D009414:Nerve Growth Factors