Intensity modulation of TMS-induced cortical excitation

Primary motor cortex

Peter T. Fox, Shalini Narayana, Nitin Tandon, Sarabeth P. Fox, Hugo Sandoval, Peter Kochunov, Charles Capaday, Jack L. Lancaster

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

The intensity dependence of the local and remote effects of transcranial magnetic stimulation (TMS) on human motor cortex was characterized using positron-emission tomography (PET) measurements of regional blood flow (BF) and concurrent electromyographic (EMG) measurements of the motor-evoked potential (MEP). Twelve normal volunteers were studied by applying 3 Hz TMS to the hand region of primary motor cortex (M1hand). Three stimulation intensities were used: 75%, 100%, and 125% of the motor threshold (MT). MEP amplitude increased nonlinearly with increasing stimulus intensity. The rate of rise in MEP amplitude was greater above MT than below. The hemodynamic response in M1hand was an increase in BF. Hemodynamic variables quantified for M1hand included value-normalized counts (VNC), intensity (z-score), and extent (mm3). All three hemodynamic response variables increased nonlinearly with stimulus intensity, closely mirroring the MEP intensity-response function. VNC was the hemodynamic response variable which showed the most significant effect of TMS intensity. VNC correlated strongly with MEP amplitude, both within and between subjects. Remote regions showed varying patterns of intensity response, which we interpret as reflecting varying levels of neuronal excitability and/or functional coupling in the conditions studied.

Original languageEnglish (US)
Pages (from-to)478-487
Number of pages10
JournalHuman Brain Mapping
Volume27
Issue number6
DOIs
StatePublished - Jun 1 2006
Externally publishedYes

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Motor Evoked Potentials
Transcranial Magnetic Stimulation
Motor Cortex
Hemodynamics
Regional Blood Flow
Positron-Emission Tomography
Healthy Volunteers
Hand

All Science Journal Classification (ASJC) codes

  • Anatomy
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Clinical Neurology

Cite this

Fox, P. T., Narayana, S., Tandon, N., Fox, S. P., Sandoval, H., Kochunov, P., ... Lancaster, J. L. (2006). Intensity modulation of TMS-induced cortical excitation: Primary motor cortex. Human Brain Mapping, 27(6), 478-487. https://doi.org/10.1002/hbm.20192

Intensity modulation of TMS-induced cortical excitation : Primary motor cortex. / Fox, Peter T.; Narayana, Shalini; Tandon, Nitin; Fox, Sarabeth P.; Sandoval, Hugo; Kochunov, Peter; Capaday, Charles; Lancaster, Jack L.

In: Human Brain Mapping, Vol. 27, No. 6, 01.06.2006, p. 478-487.

Research output: Contribution to journalArticle

Fox, PT, Narayana, S, Tandon, N, Fox, SP, Sandoval, H, Kochunov, P, Capaday, C & Lancaster, JL 2006, 'Intensity modulation of TMS-induced cortical excitation: Primary motor cortex', Human Brain Mapping, vol. 27, no. 6, pp. 478-487. https://doi.org/10.1002/hbm.20192
Fox, Peter T. ; Narayana, Shalini ; Tandon, Nitin ; Fox, Sarabeth P. ; Sandoval, Hugo ; Kochunov, Peter ; Capaday, Charles ; Lancaster, Jack L. / Intensity modulation of TMS-induced cortical excitation : Primary motor cortex. In: Human Brain Mapping. 2006 ; Vol. 27, No. 6. pp. 478-487.
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