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Galvanic Skin Response (GSR) is a widely used physiological parameter that reflects variations in skin conductance arising from sweat gland activity. Since these glands are under the control of the sympathetic nervous system, changes in GSR provide a reliable indication of emotional arousal, stress, and other autonomic reactions. The measurement is typically made in regions where the density of sweat glands is high, allowing small fluctuations in sympathetic activity to produce detectable changes in voltage output due to change in skin resistance. To obtain dependable readings from such subtle variations, a stable and well- defined excitation source is essential. For this purpose, GSR systems commonly employ a constant current source. By delivering a small, steady current through the skin, the circuit ensures that any change in voltage across the electrodes truly represents a physiological change rather than a variation in the measuring device. This approach improves linearity, reduces the influence of electrode polarization, and enhances the overall accuracy of the measurement. For its sensitivity and simplicity, the GSR technique has become an important tool in psychological studies, biofeedback training, and clinical monitoring of autonomic function.