Motor Evoked Potential (MEP) refers to the electrical activity generated by muscles in response to stimulation of the motor cortex through a non-invasive technique called transcranial magnetic stimulation (TMS). MEP is a neurophysiological measurement used to evaluate the functional integrity and conduction efficiency of the motor pathway, specifically the corticospinal tract.
During the measurement of MEP, a magnetic field is applied over the scalp, inducing a brief and focused current flow in the underlying motor cortex. This magnetic pulse triggers depolarization of the corticospinal neurons, leading to the generation of action potentials that propagate down to the spinal cord and subsequently activate muscle fibers. The resulting electromyographic response is detected through surface electrodes placed on the target muscle, typically the muscles of the upper or lower limb, allowing for the evaluation of changes in muscle activity.
MEP assessments are widely used in clinical and research settings to investigate motor system anomalies, monitor recovery after stroke, evaluate spinal cord abnormalities, study cortical excitability, assess response to treatment, and study motor neurophysiology. By quantifying MEP characteristics such as amplitude, latency, duration, and onset slope, important information about the integrity, excitability, and efficiency of the motor pathway can be obtained.
Overall, Motor Evoked Potential is a valuable tool in neurophysiology that allows for the non-invasive assessment of the motor system and aids in the understanding and diagnosis of various neurological conditions.
