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Neuroscience JoVE (Open Access) Citable · DOI

Stimulating the Lip Motor Cortex with Transcranial Magnetic Stimulation

DOI: 10.3791/51665-v
What you'll learn
  • ✓ Record motor evoked potentials from lip muscles using TMS
  • ✓ Localize motor lip representation in human cortex
  • ✓ Apply single-pulse and repetitive TMS protocols to disrupt motor function
  • ✓ Define motor thresholds for safe TMS stimulation parameters
Protocol

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. This article describes how to record motor evoked potentials (MEPs) from the lip muscles and how to disrupt the motor lip representation using repetitive TMS.

Difficulty
advanced
Total time
~2-3 hours per participant (including preparation, localization, threshold determination, and stimulation protocols)

Steps

1
Prepare subject for transcranial magnetic stimulation

Set up participant positioning, apply EMG electrodes to lip muscles, and configure TMS coil placement apparatus. Ensure comfort and safety measures are in place before stimulation begins.

▶ 01:41
2
Localize motor hand representation as anatomical reference

Use single-pulse TMS to identify the hand motor area and establish baseline motor evoked potential responses. This serves as a known anatomical landmark for subsequent lip motor cortex localization.

▶ 03:45
3
Localize motor lip representation and set stimulus intensity

Systematically map the lip motor cortex using TMS and record MEPs from lip muscles. Determine optimal stimulation intensity for single-pulse experiments based on motor response amplitude.

▶ 05:10
4
Define motor threshold and apply low-frequency repetitive TMS

Establish active motor threshold for rTMS experiments. Apply low-frequency repetitive TMS to disrupt motor lip representation and measure resulting changes in motor cortex excitability.

▶ 07:31
5
Analyze single-pulse and repetitive TMS experimental results

Compare motor evoked potentials and motor maps before and after single-pulse or repetitive TMS protocols. Quantify changes in motor cortex representation and excitability.

▶ 09:22
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