1 23 Journal of Neuroimmune Pharmacology ISSN 1557-1890 J Neuroimmune Pharmacol DOI 10.1007/s11481-012-9383-y Measuring GABAergic Inhibitory Activity with TMS-EEG and Its Potential Clinical Application for Chronic Pain Mera S. Barr, Faranak Farzan, Karen D. Davis, Paul B. Fitzgerald & Zafiris J. Daskalakis