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Of several candidate mechanisms underlying induced changes of excitability, alterations of synaptic efficacy, such as long-term-potentiation or long-term-depression may be particularly relevant, because they concern mechanisms that have been implicated in learning and memory. Low-frequency median nerve stimulation was paired with transcranial magnetic stimulation (TMS) over the optimal cranial site for stimulating the abductor pollicis brevis muscle (APB). This protocol induced an increase in the amplitudes of the motor evoked potentials in the resting APB as well as a prolongation of the silent period measured in the precontracted APB following TMS. Plasticity induced by paired associative stimulation (PAS) evolved rapidly (within 30 min), was persistent minimum 30-60 min duration), yet reversible, and was topographically specific. Further experiments showed that PAS-induced plasticity was located cortically, did not involve changes of cortical GABA A -receptor dependent inhibition and depended on the activation of NMDA-receptors.

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2003-09-01   |   275 visitas   |   Evalua este artículo 0 valoraciones

Vol. 26 Núm.4. Diciembre 2001 Pags. 01-51 Rev Neurol Arg 2001; 26(Supl 1)