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Active vs. Passive Movements for Control Signals
  • Neuroengineering
  • Human
  • Grade 6+

Active vs. Passive Movements – Does the Brain Need to Initiate EMG Signals?

Can muscles spark electrical activity without direct brain commands? Explore the difference between voluntary (active) muscle contractions and externally induced (passive) movements to reveal some secrets of the EMG.

Devices and Accessories3Related Experiments2

About the Experiment

What Will You Learn?

What Will You Learn?

  • How EMG differs between active and passive muscle movement.
  • How the brain contributes to muscle electrical activity.
  • Ways to distinguish neurally driven from passive EMG responses.
Background

Background

EMG is all about the electrical chatter of muscles. But what if those muscles are moving without our input? Via the Human-Human Interface, you'll see whether EMG depends on neural drive.

Procedure

  1. Safety First:

    Both volunteers must understand the procedure and agree to take part. The Minion must not take part with a pacemaker or other implanted electronic device, metal implants, epilepsy, a heart condition, or pregnancy. Turn the HHI off before attaching, moving or removing stimulation electrodes; start at the lowest intensity and raise it slowly; stop at once if it hurts or either volunteer asks. Keep both stimulation electrodes on one forearm—never across the chest, throat, neck or head.

  2. Electrode Placement:

    1. Attach electrode patches to the Controller’s forearm and connect to the Human-Human Interface.
    2. Connect the stimulation electrodes to the Minion.
    3. Verify an EMG signal from the Controller causes the minion to flex.

  3. Active Condition:

    1. Flex the muscle voluntarily.
    2. Record EMG amplitude, frequency and pattern and see how much the Minion moves.

  4. Passive Movement:

    1. Completely relax the muscle.
    2. Have a partner passively move the limb while recording EMG.
    3. Compare the passive EMG with the active condition and see how much the Minion moves now.
Results & Analysis

Results & Analysis

Do EMG bursts show up if the arm is moved by someone else? Did the Minion still respond? How did the two conditions compare in terms of EMG power? Does lacking the brain’s intent‑to‑move signal also mean no EMG signal?