Figure 4.

Voltage-controlled Stimulation. (A): Glutamate release in the thalamus in one rat evoked by monophasic voltage-controlled stimulation (60-90 V) compared to 0.5 mA current-controlled stimulation with stimulation frequency and pulse width held constant (100 Hz, 0.5 msec). (B): Comparison of current-controlled and voltage stimulations. Each line represents the linear regression of peak glutamate extracellular concentrations attained with 10 seconds of current-controlled stimulations for four rats. Symbols correspond to peak glutamate extracellular concentrations obtained in these animals. (C): Comparison of stimulation voltages measured across electrode contact during 0.1 mA current-controlled stimulation (left) and a comparable 4V voltage-controlled stimulation (right). (D): The first pulse of both stimulations showing differences in the interpulse decay for current-controlled (solid line) and voltage-controlled (dashed line) stimulations. (E): Voltages measured across electrode contacts during current-controlled stimulations with increasing current intensities (0.05-0.3 mA). (F): Voltages measured across electrode contacts during voltage-controlled stimulations of increasing voltage intensities (1-9 V). (G): Overlap of the last pulse of 1 sec long stimulation train delivered with voltage-controlled stimulation showing the interpulse decay is minimal with respect to a relatively higher stimulation voltage of 90 V. (H): Peak current measured at different applied voltage-controlled stimulations (1-90 V).