Table 1. Comparison between some experimental animal and clinical human studies

	Stimulation type	Electrode diameter (mm)	Electrode material	Pulse duration (ms)	Intensity (mA)	frequency (Hz)	Charge/ph (μC/ph)	Charge density/pH (μC/cm2/ph)	Neural damage
Experimental animal studies
Pudenz et al. 1977 [22]	Bipolar	1.1, 1.4	Pt, Rh	0.1 to 0.5	3, 6	50	0.3 to 3.0	30 to 300	+
Agnew et al. 1977 [50]		1.4	Pt	0.25	3	50			+
Yuen et al. 1981 [23]		1.1	Pt	0.1 to 1.0	1.6 to 4	50	216 to 720	40 to 400	+
Babb and Kupfer 1981 [27]	Bipolar	0.2	NiCr or Stainless steel	0.1	0.5 to 2	2.5 to 240	0.4 to 14.4	11.11 to 66.6	+
Agnew et al. 1983 [51]		1.1	Pt	0.25	-	20, 50	-	20, 100	+
McCreepy et al. 1988 [52]		1.1, 1.0	Pt, Ta	0.4	> 2.5	50	0.8 to 1	80 to 100	+
McCreepy et al. 1990 [53]		-	Pt	0.4	-	50	0.05 to 18	10 to 1,600	+
Oinuma et al. 2007 [28]	Monopolar	1.0	Ag	0.2	1.5 to 50	500	0.3 to10	0.3 to 10	+
Intraoperative testing (clinical human studies)
Penfield and Jasper 1954 [4]	Bipolar	1.0	-	2.0	-	60	-	-
Ojemann 1979 [54]	Bipolar	1.0	-	1.25	5 to 10	60	5.0	159
Robertson 1979 [55]		3.5	Pt	0.5,1.0	-	10	-	-	+
Gordon et al. 1990 [9]	Bipolar	3.175	Stainless steel, 90%Pt–10%Ir	0.3	12 to 15	50	4.4	5.7
King and Schell 1987 [56]	Bipolar	-	-	1.0	3 to 10	50	3 to 10	300 to 1,000
Ojemann et al. 1989 [57]	Bipolar	1.0	-	1.25	1.5 to 10	60	10.0	1,000
Berger et al. 1990 [58]	Bipolar	1.0	-	1.25	2 to 16	60	10.0	1,000
Taniguchi et al. 1993 [6]	Monopolar	-	-	0.4	< 20	500	<8	<8

Pt: platinum; Rh: rhodium; Ir: iridium; NiCr: nichrome; Ta: tantalum.