ELEC 240 Lab
The Project Objective
In this final project, we will be seeing (and hearing) how our body uses electricity to communicate. The first step to doing this is to sense the electrical activity. Electrodes are electrical conductors that sense ion distributions on tissue and convert that ion current into an electrical current. For this project, we will pick a noninvasive option for sensing bioelectrical signals by using body surface electrodes to detect the electrical activity that occurs when a muscle contracts.
This electrical activity is in the microvolts range and not detectable directly by our lab instruments. So we will need to amplify and filter the signal, and create appropriate interfacing that will allow us to both visualize and hear the signal, and give us some interesting information about it.
Muscle Bioelectrical Signals
When you decide to move a muscle, upper motor neurons from your motor cortex travel to your spinal cord where they synapse with lower motor neurons. These lower motor neurons synapse with multiple muscle fibers to form a motor unit. Each muscle fiber is made up of actin/myosin chains that slide across each other when there is a specific voltage potential, changing the muscle fiber shape.
When a motor neuron fires an electrical impulse creating an action potential, acetylcholine is released at the synapse, or the neuromuscular junction, causing a change in the electrical potential of the muscle. This causes voltage-gated calcium channels to open and propagate the action potential across the muscle cells, creating a muscle contraction.
The action potentials that occur in the muscle can be sensed by body surface electrodes. We will build an instrument called an electromyogram (EMG) that will amplify and process this signal into a detectable and informative signal.
If you'd like to learn more about this process and how you can simulate simple neurons, ELEC382: "Introduction to Computational Neuroscience" is a great course for it!