Ghasemi, Rasoul, Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Chamran highway, Velenjak, Tehran, Iran, Phone: + 98 21 22439971, E-mail: Rghasemi60@sbmu.ac.ir; r_ghasemi60@yahoo.com, Iran, Islamic Republic of