Ever wondered how it feels to control—or be controlled by—someone else? In this lab you’ll dive into the world of neural communication and motor control with our Human-Human Interface experiment.
Moving lets us explore the world—walking, dancing, or even controlling a robotic limb. Neurons in the motor cortex fire, signals travel down the spinal cord, and muscles contract. By linking two participants, you’ll experience how those signals can “borrow” another person’s muscles, revealing the power of functional electrical stimulation and the promise of neuroprosthetics.
Materials:
Setup: Two volunteers choose roles: Controller (sends the signal) and Minion (receives stimulation).
Place two EMG patch electrodes on the forearm flexor muscle and a ground patch on the back of the hand. Clip the red leads to the muscle patches and the black lead to ground. Plug the orange cable into the HHI and turn it on. Ask the Controller to flex; all LEDs should light with a strong squeeze. Use the black button to adjust gain if needed.
Turn off the HHI. Place the two square stimulation electrodes across the ulnar nerve on the back of the forearm, just below the elbow (adjust as needed). Connect the black FES cable to the HHI’s Minion port. When ready, power the device back on.
Power on the HHI with the intensity set low. The Controller flexes to light the red LED (threshold). The Minion keeps their forearm relaxed at 90° elbow flexion. Gradually turn the intensity knob until the Minion’s hand twitches—this is the threshold. If the Minion is comfortable, increase intensity to evoke a stronger motion. If stimulation is felt but movement is absent, adjust electrode placement.
Describe the sensations as Controller and as Minion. Measure reaction threshold (LED level vs. intensity dial) and note latency between flex and Minion movement. Discuss how functional electrical stimulation can bridge damaged neural pathways and how signal strength maps to muscle activation.
