Muscle Contraction

Our muscles are capable of contracting with the use of action potentials. An action potential occurs within neurons in the muscles that can be defined as specialized cells that make up the nervous system and transmit nerve impulses. A neuron in its resting state is negative on the inside and positive on the outside due to a concentration gradient of ions. When the neuron receives a signal (physical change in our case) ions rush into and out of the cell, which creates an electrical flow in the neuron causing the inside to become positive and outside to become negative (depolarization). The flow of ions occurs through several channels in the axon of the neuron. With the electrodes, we will be sensing the depolarization of the muscle cell in the given orbital muscle resulting from neuronal activity occurring within the axon. Therefore, when the muscle is being used or activated, an action potential will be sent to the neurons, depolarizing them, and creating an overall positive output of voltage. When reading an EOG signal, we can establish when the cells in the muscle are polarizing (deactivated) and depolarizing (activated). When the cells in the muscle depolarize it becomes more positive causing the signal to rise. When the cells polarize it becomes more negative causing the signal to drop (6). the depolarization 

 

Figure 8: Image of a neuron (5)