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The effects of inhibitory and facilitatory intracortical circuits on interhemispheric inhibition in the human motor cortex.
Lee, Hubert; Gunraj, Carolyn; Chen, Robert.
Afiliação
  • Lee H; Division of Neurology, Krembil Neuroscience Centre and Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.
J Physiol ; 580(Pt.3): 1021-32, 2007 May 01.
Article em En | MEDLINE | ID: mdl-17303638
ABSTRACT
Inhibitory and facilitatory intracortical pathways regulating motor cortical output can be studied non-invasively in humans with transcranial magnetic stimulation. These circuits include short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI) and intracortical facilitation (ICF). Stimulation of the motor cortex also inhibits the contralateral motor cortex (interhemispheric inhibition, IHI) at short (approximately 10 ms, IHI10) or long intervals (approximately 40 ms, IHI40). We investigated how SICI, ICF, and LICI influence IHI10 and IHI40. We hypothesize that intracortical circuits will have similar effects on IHI and cortical output neurons SICI and LICI will decrease IHI, and ICF will increase it. Motor evoked potentials were recorded from the first dorsal interosseous muscles bilaterally in 10 healthy subjects. We compared IHI10 and IHI40 alone to IHI10 and IHI40 elicited in the presence of SICI, ICF, or LICI. Our results showed that SICI and LICI reduced IHI10, IHI40 and corticospinal output to a similar degree. ICF increased corticospinal output but had no effect on either IHI10 or IHI40. The different effects of ICF on corticospinal excitability and IHI suggest the transcallosal fibres mediating IHI and the corticospinal output system arise from different neuronal populations. SICI and LICI produce more global inhibition with similar effects on the transcallosal and descending corticospinal circuits.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Córtex Motor / Inibição Neural Limite: Adult / Female / Humans / Male / Middle aged Idioma: En Ano de publicação: 2007 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Córtex Motor / Inibição Neural Limite: Adult / Female / Humans / Male / Middle aged Idioma: En Ano de publicação: 2007 Tipo de documento: Article