liikeärsykkeet

Liikeärsykkeet, also known as motor evoked potentials (MEPs), are a neurophysiological technique used to assess the integrity of the motor pathways in the nervous system. This method involves stimulating the motor cortex, typically using transcranial magnetic stimulation (TMS) or direct electrical stimulation, and then recording the resulting electrical activity in the muscles. The recorded signals, the MEPs, provide information about how efficiently and effectively the neural impulses travel from the brain down to the muscles.

The procedure for eliciting and measuring MEPs is relatively straightforward. A TMS coil is placed on the scalp over the motor cortex corresponding to the muscle being tested. A brief, intense magnetic pulse is delivered through the coil, which induces an electrical current in the underlying brain tissue, depolarizing neurons in the motor cortex. This initiates an action potential that travels down the corticospinal tract. Electromyography (EMG) electrodes are then attached to the target muscle to record the muscle's electrical response to this descending signal.

The characteristics of the recorded MEP, such as its amplitude, latency (the time it takes to appear), and shape, can reveal important information about the functioning of the motor system. For example, a reduced MEP amplitude or prolonged latency may indicate damage or dysfunction along the motor pathway, such as in the brain or spinal cord. This technique is valuable in diagnosing and monitoring neurological conditions affecting motor control, including stroke, multiple sclerosis, spinal cord injury, and peripheral nerve disorders. It can also be used in research settings to investigate motor control mechanisms and the effects of therapeutic interventions.