The effects of inhibitory and facilitatory intracortical circuits on interhemispheric inhibition in the human motor cortex

@article{citeulike:1235930, 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 (\~{}10 ms, IHI10) or long intervals (\~{}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.}, author = {Lee, Hubert and Gunraj, Carolyn and Chen, Robert }, citeulike-article-id = {1235930}, doi = {http://dx.doi.org/10.1113/jphysiol.2006.126011}, issn = {0022-3751}, journal = {The Journal of Physiology}, keywords = {emg, inhibition, medicin, motorcortex, neuroscience, tms, transcallosalinhibition}, month = {May}, number = {3}, pages = {1021--1032}, posted-at = {2007-08-24 12:32:32}, priority = {2}, publisher = {Blackwell Publishing}, title = {The effects of inhibitory and facilitatory intracortical circuits on interhemispheric inhibition in the human motor cortex}, url = {http://dx.doi.org/10.1113/jphysiol.2006.126011}, volume = {580}, year = {2007} }

TY - JOUR ID - citeulike:1235930 L3 - citeulike-article-id:1235930 TI - The effects of inhibitory and facilitatory intracortical circuits on interhemispheric inhibition in the human motor cortex JF - The Journal of Physiology VL - 580 IS - 3 SP - 1021 EP - 1032 PB - Blackwell Publishing SN - 0022-3751 N2 - 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 (~10 ms, IHI10) or long intervals (~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. KW - emg KW - inhibition KW - medicin KW - motorcortex KW - neuroscience KW - tms KW - transcallosalinhibition AU - Lee, Hubert AU - Gunraj, Carolyn AU - Chen, Robert PY - 2007/05// UR - http://dx.doi.org/10.1113/jphysiol.2006.126011 ER -