JoVE Encyclopedia of Experiments
Neuroscience
0 views • 6:40 min • July 8th, 2025
Take a human patient's hand. Place a negative electrode on the first dorsal interosseous, or FDI, muscle to record its activity. Place a positive electrode on the distal joint and a reference electrode on the wrist to establish baseline signal.
Position a force-measuring device between the thumb and the index finger.
Maintain a standardized force on the device and record the muscle activity.
Locate the primary motor cortex, or M1, on the contralateral side of the brain that regulates FDI activity.
Position a magnetic coil on M1 and identify the lowest-intensity threshold stimulus to generate action potentials in cortical neurons that lead to FDI contraction, known as motor-evoked potential or MEP.
Deliver a suprathreshold pulse to elicit a high-amplitude MEP.
The cortical interneurons release inhibitory neurotransmitters that block cortical neurons, preventing excessive muscle activity.
Record the contralateral silent period, or cSP, a period of reduced muscle activity before voluntary activity returns.
To select the muscle for positioning the electrodes, ask the subject to put their hand over the table in a prone position. Then, to identify the first dorsal interosseous or FDI mus
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