Final answer:
Electrodermal Activity (EDA), or skin conductance, is a measure of the electrical conductance of the skin that varies with sweat gland activity and reflects sympathetic nervous system arousal. It's commonly recorded along with other physiological electric potentials, such as those in ECGs and EEGs, offering insights into emotional and physiological states.
Step-by-step explanation:
Electrodermal Activity (EDA), also known as skin conductance, is a biological phenomenon that reflects the electrical conductance of the skin and is influenced by the sweat gland activity. This activity is indicative of the sympathetic nervous system's responses, which can be measured using electrodes on the skin to detect subtle changes in sweat secretion, corresponding to emotional or physiological arousal. Such measurements provide data valuable in various fields, including psychology, medicine, and neuroscience.
When electrodes are attached to the skin, they can record various physiological electric potentials, such as those related to the brain and heart. For instance, the electrical impulses in the heart produce electrical currents that flow through the body and manifest on the skin surface. These can be measured and displayed as an electrocardiogram (ECG), showing the electrical impulses of the cardiac muscle. Additionally, biological fluids contain ions that produce electrical charges within the body, and the interactions of these ions can be observed in the form of waves on both an ECG and an electroencephalogram (EEG).
The difference in ionic concentrations across semipermeable membranes creates electric potentials in neurons and other cells, leading to nerve signals that can be recorded and analyzed. Electric eels, for example, can generate strong electric fields used to stun prey via a similar mechanism of depolarization and repolarization in their muscle cells. This same principle underlies the electrodermal responses in humans, albeit on a much smaller and less dramatic scale.