Pergolide Increases the Efficacy of Cathodal Direct Current Stimulation to Reduce the Amplitude of Laser-Evoked Potentials in Humans  Daniella Terney, MD, Inga Bergmann, Csaba Poreisz, MD, Leila Chaieb, MSc, Klára Boros, MD, Michael Andreas Nitsche, MD, Walter Paulus, MD, Andrea Antal, PhD  Journal of Pain and Symptom Management  Volume 36, Issue 1, Pages 79-91 (July 2008) DOI: 10.1016/j.jpainsymman.2007.08.014 Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

Fig. 1 Experimental procedure: Pergolide or an equivalent placebo drug was taken by all subjects orally two hours before the start of the experiments (2.5 hours before tDCS). First, the left motor-cortical representational field of the right abductor digiti minimi was identified using TMS. During electroencephalogram recording, we delivered 40 laser pulses to each hand before tDCS. Afterward, cathodal tDCS was performed for 15 minutes, followed by 40 laser pulses to each hand immediately after the stimulation, 40minutes, two hours, and 24 hours later. Journal of Pain and Symptom Management 2008 36, 79-91DOI: (10.1016/j.jpainsymman.2007.08.014) Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

Fig. 2 The differences between numeric analog score results at four time points (standardized data by calculating the after 1–4/before ratio), for the two medication conditions (pergolide, placebo) and control experiment for both hands with laser stimulation. The standardized numeric analog score results show either an increase in pain sensation or a decline, relative to one. Following cathodal tDCS, the pain sensation was lowered up to 40minutes. The asterisks indicate significant differences between the different time points. Journal of Pain and Symptom Management 2008 36, 79-91DOI: (10.1016/j.jpainsymman.2007.08.014) Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

Fig. 3 Grand averages of LEPs obtained by both hand laser stimulation for the Cz recording electrode. The solid line shows LEPs for placebo medication combined with tDCS and the intermittent line for pergolide medication combined with tDCS at five different time points (before, after tDCS 0min, after tDCS 40min, after tDCS two hours, after tDCS 24 hours). Note that 24 hours following tDCS a greater amplitude reduction of the N2 component and N2P2 peak-to-peak amplitude for pergolide medication is observed when compared to placebo medication. The asterisk indicates a significant difference between the pergolide and placebo conditions. Journal of Pain and Symptom Management 2008 36, 79-91DOI: (10.1016/j.jpainsymman.2007.08.014) Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

Fig. 4 The differences between mean N2 amplitude values at four time points (standardized data by calculating the after 1–4/before ratio), for the two medication conditions (pergolide, placebo) and control experiment for both hands laser stimulation at the Cz electrode. The standardized peak amplitudes show either an increase in the amplitude of the N2 component or a decline, relative to a value of one. Our results confirm that cathodal tDCS significantly reduced the amplitude of the N2 component when compared to the control experiment. The pergolide medication prolonged this effect for up to 24 hours. The symbols indicate significant differences between the pergolide and placebo medications (0) or differences between time points (*). Journal of Pain and Symptom Management 2008 36, 79-91DOI: (10.1016/j.jpainsymman.2007.08.014) Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions