Epilepsies and neuronal plasticity: for better or for worse?
Extensive experimental investigations have confirmed that "seizures beget seizures." Thus, in adults, limbic seizures lead to cell loss, followed by the formation of novel excitatory synapses that contribute to generating further seizures. The triggering signal is an enhancement of synaptic efficacy, followed by a molecular cascade that triggers axonal sprouting. New synapses are aberrant, since they are formed in regions in which they are not present in controls. They also involve receptors that are not present in controls, and this facilitates the generation of seizures. Therefore, an aberrant form of reactive neuronal plasticity provides a substrate for the long-lasting sequelae of seizures. Since these events take place in brain structures involved in integrative and mnemonic functions, they will have an important impact. Reactive plasticity is documented for other insults and disorders, and may be the basis for the long-term progression of neurodegenerative disorders.
Ben-Ari
Yehezkel
Y
French Medical Research Council, INSERM U29-INMED, Marseille, France. ben-ari@inmed.univ-mrs.fr
D000818:Animals; D004827:Epilepsy / Q000378:metabolism / Q000503:physiopathology*; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism / Q000503:physiopathology; D006624:Hippocampus / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D019599:Mossy Fibers, Hippocampal / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009415:Nerve Net / Q000378:metabolism / Q000503:physiopathology*; D009433:Neural Inhibition; D009434:Neural Pathways / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009473:Neuronal Plasticity; D018092:Kainic Acid Receptors / Q000235:genetics / Q000378:metabolism
D018092:Kainic Acid Receptors