Related Experiment Video
Updated: May 20, 2026
Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation
Published on: February 23, 2020
Relation of brain stimulation induced changes in MEP amplitude and BOLD signal
Lucia Kriváneková1, Simon Baudrexel, Barbara Bliem
1Department of Neurology, Goethe University of Frankfurt, Schleusenweg 2-16, D-60528 Frankfurt am Main, Germany.
Background:
Non-invasive human brain stimulation can induce long-term plasticity reflected by changes in putative markers of synaptic activation, such as the motor evoked potential (MEP) amplitude elicited by transcranial magnetic stimulation or the task-dependent blood oxygenation level-dependent (BOLD) signal measured by functional magnetic resonance imaging.
Objective:
To study the relationship between brain stimulation induced changes in MEP amplitude and BOLD signal.
Methods:
Paired associative stimulation of the hand area of the left primary somatosensory cortex (S1-PAS) was applied in 15 healthy subjects to induce excitability change in the adjacent primary motor cortex (M1) [Kriváneková et al. 2011, Eur J Neurosci 34:1292-1300]. Before and after S1-PAS, MEP amplitude in a right hand muscle, and the BOLD signal during a right hand motor or somatosensory activation task were measured.
Results:
S1-PAS resulted in substantial individual MEP and BOLD signal changes, but these changes did not correlate in M1 or S1.
Conclusions:
Findings indicate that MEP amplitude and BOLD signal within the tested M1 reflect physiologically distinct aspects of synaptic excitability change. Therefore, it is suggested that MEP amplitude and BOLD signal are complementary rather than interchangeable markers of synaptic excitability.
