E1: How EEG detects brain activity.
Introduction.
Brain cells communicate through electrical impulses facilitated by nerve cells. An electroencephalogram (EEG) can be used to evaluate this electrical activity within the brain. Some typical uses of EEG monographs are used to substantiate the diagnoses of seizure and sleep disorders and stroke.
The monograph is created by attaching electrodes to the patients scalp to measure differences in electrical potential.
Understanding neurons. Typical neurons are composed of three parts a cell body, which contains the nucleus. Branched dendrites and a terminal axon are surrounded by myelin sheaths that accelerate the signalling. The selectively-permeable membrane of a neuron regulates internal and external ion concentration of which Na+ , Cl– and K+ are of most importance. A disequilibrium known as the resting or steady state of a neuron holds the potential difference at V = -70 mV with respect to the extracellular fluid. This is maintained by the membrane through active transport of sodium and potassium out the membrane.
The Action Potential.…show more content… It is proceeded by depolarisation, where in similar fashion, potassium ions exit the neuron and the potential drops back to V = -70 mV in repolarisation where potassium ions exit the cell. This is known as the action potential. The action potential always has the same magnitude and duration, no matter the location. As such, a single action potential can only inform the nervous system of presence or occurrence while more complex signals are created by variations in frequency of action
