Format

Send to

Choose Destination
Brain Stimul. 2018 Mar - Apr;11(2):322-326. doi: 10.1016/j.brs.2017.10.014. Epub 2017 Oct 20.

Transcranial magnetic stimulation modulation of corticospinal excitability by targeting cortical I-waves with biphasic paired-pulses.

Author information

1
Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
2
Nexstim Plc, Helsinki, Finland.
3
Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
4
Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland. Electronic address: petro.julkunen@kuh.fi.

Abstract

BACKGROUND:

Transcranial magnetic stimulation (TMS) induced I-wave behavior can be demonstrated at neuronal population level using paired-pulses and by observing short-interval cortical facilitation (SICF). Advancements in stimulator technology have made it possible to apply biphasic paired-pulses to induce SICF.

OBJECTIVE:

Our aim was to characterize the SICF I-wave interaction by biphasic paired-pulses with the ultimate objective to enhance TMS effects via SICF in various TMS-applications.

METHODS:

We used biphasic paired-pulses in 15 volunteers to characterize corticospinal SICF using various 1.2-8.0ms inter-stimulus intervals, and measuring SICF input-output response.

RESULTS:

SICF interaction with the first I-wave (I1) was observed in the output responses (motor evoked potentials; MEPs) in all subjects. Most subjects (≥80%) also exhibited later SICF I-wave interaction. SICF at I1 was present at all applied intensities below 140% of resting motor threshold. At I2, we observed SICF only with intensities just above motor threshold.

CONCLUSIONS:

Biphasic paired-pulses can reliably induce SICF shown by the facilitatory I-wave interaction, and could therefore be applied with repetitive bursts to enhance responsiveness to TMS.

KEYWORDS:

Biomedical engineering; Indirect wave; Motor cortex; Motor evoked potential; Short-interval intracortical facilitation; Transcranial magnetic stimulation

PMID:
29089235
DOI:
10.1016/j.brs.2017.10.014

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center