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Effect of low-frequency repetitive transcranial magnetic stimulation on interhemispheric inhibition.
J Neurophysiol. 2005 Sep; 94(3):1668-75.JN

Abstract

We studied the effects of 1-Hz repetitive transcranial magnetic stimulation (rTMS) on the excitability of interhemispheric connections in 13 right-handed healthy volunteers. TMS was performed using figure-eight coils, and surface electromyography (EMG) was recorded from both first dorsal interosseous (FDI) muscles. A paired-pulse method with a conditioning stimulus (CS) to the motor cortex (M1) followed by a test stimulus to the opposite M1 was used to study the interhemispheric inhibition (ppIHI). Both CS and TS were adjusted to produce motor-evoked potentials of approximately 1 mV in the contralateral FDI muscles. After baseline measurement of right-to-left IHI (pre-RIHI) and left-to-right IHI (pre-LIHI), rTMS was applied over left M1 at 1 Hz with 900 stimuli at 115% of resting motor threshold. After rTMS, ppIHI was studied using both the pre-rTMS CS (post-RIHI and post-LIHI) and an adjusted post-rTMS CS set to produce 1-mV motor evoked potentials (MEPs; post-RIHI(adj) and post-LIHI(adj)). The TS was set to produce 1-mV MEPs. There was a significant reduction in post-LIHI (P = 0.0049) and post-LIHI(adj) (P = 0.0169) compared with pre-LIHI at both interstimulus intervals of 10 and 40 ms. Post-RIHI was significantly reduced compared with pre-RIHI (P = 0.0015) but pre-RIHI and post-RIHI(adj) were not significantly different. We conclude that 1-Hz rTMS reduces IHI in both directions but is predominantly from the stimulated to the unstimulated hemisphere. Low-frequency rTMS may be used to modulate the excitability of IHI circuits. Treatment protocols using low-frequency rTMS to reduce cortical excitability in neurological and psychiatric conditions need to take into account their effects on IHI.

Authors+Show Affiliations

Divsion of Neurology and Krembil Neuroscience Centre, Toronto Western Research Institute, University Health Network, University of Toronto, Ontario, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15872061

Citation

Pal, Pramod Kr, et al. "Effect of Low-frequency Repetitive Transcranial Magnetic Stimulation On Interhemispheric Inhibition." Journal of Neurophysiology, vol. 94, no. 3, 2005, pp. 1668-75.
Pal PK, Hanajima R, Gunraj CA, et al. Effect of low-frequency repetitive transcranial magnetic stimulation on interhemispheric inhibition. J Neurophysiol. 2005;94(3):1668-75.
Pal, P. K., Hanajima, R., Gunraj, C. A., Li, J. Y., Wagle-Shukla, A., Morgante, F., & Chen, R. (2005). Effect of low-frequency repetitive transcranial magnetic stimulation on interhemispheric inhibition. Journal of Neurophysiology, 94(3), 1668-75.
Pal PK, et al. Effect of Low-frequency Repetitive Transcranial Magnetic Stimulation On Interhemispheric Inhibition. J Neurophysiol. 2005;94(3):1668-75. PubMed PMID: 15872061.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of low-frequency repetitive transcranial magnetic stimulation on interhemispheric inhibition. AU - Pal,Pramod Kr, AU - Hanajima,Ritsuko, AU - Gunraj,Carolyn A, AU - Li,Jie-Yuan, AU - Wagle-Shukla,Aparna, AU - Morgante,Francesca, AU - Chen,Robert, Y1 - 2005/05/04/ PY - 2005/5/6/pubmed PY - 2005/10/12/medline PY - 2005/5/6/entrez SP - 1668 EP - 75 JF - Journal of neurophysiology JO - J. Neurophysiol. VL - 94 IS - 3 N2 - We studied the effects of 1-Hz repetitive transcranial magnetic stimulation (rTMS) on the excitability of interhemispheric connections in 13 right-handed healthy volunteers. TMS was performed using figure-eight coils, and surface electromyography (EMG) was recorded from both first dorsal interosseous (FDI) muscles. A paired-pulse method with a conditioning stimulus (CS) to the motor cortex (M1) followed by a test stimulus to the opposite M1 was used to study the interhemispheric inhibition (ppIHI). Both CS and TS were adjusted to produce motor-evoked potentials of approximately 1 mV in the contralateral FDI muscles. After baseline measurement of right-to-left IHI (pre-RIHI) and left-to-right IHI (pre-LIHI), rTMS was applied over left M1 at 1 Hz with 900 stimuli at 115% of resting motor threshold. After rTMS, ppIHI was studied using both the pre-rTMS CS (post-RIHI and post-LIHI) and an adjusted post-rTMS CS set to produce 1-mV motor evoked potentials (MEPs; post-RIHI(adj) and post-LIHI(adj)). The TS was set to produce 1-mV MEPs. There was a significant reduction in post-LIHI (P = 0.0049) and post-LIHI(adj) (P = 0.0169) compared with pre-LIHI at both interstimulus intervals of 10 and 40 ms. Post-RIHI was significantly reduced compared with pre-RIHI (P = 0.0015) but pre-RIHI and post-RIHI(adj) were not significantly different. We conclude that 1-Hz rTMS reduces IHI in both directions but is predominantly from the stimulated to the unstimulated hemisphere. Low-frequency rTMS may be used to modulate the excitability of IHI circuits. Treatment protocols using low-frequency rTMS to reduce cortical excitability in neurological and psychiatric conditions need to take into account their effects on IHI. SN - 0022-3077 UR - https://www.unboundmedicine.com/medline/citation/15872061/Effect_of_low_frequency_repetitive_transcranial_magnetic_stimulation_on_interhemispheric_inhibition_ L2 - http://www.physiology.org/doi/full/10.1152/jn.01306.2004?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -