Methods to Compare Predicted and Observed Phosphene Experience in tACS Subjects

Table 1

Literature-referenced tissue conductivities used in anisotropic head models. Values reported here are for tissue conductivity measured below 1 kHz. Averaged values were used if multiple tissue conductivity values below 1 kHz were found. Bone conductivity was calculated using the formula σ = (σ_can·σ_cor)^1/2 where σ_can is cancellous and σ_cor is cortical tissue conductivity value. In isotropic models, white matter conductivity was assumed to be 0.3835 S/m.

Tissue type	Conductivity values (S/m)	Reference
Air	0	—
Blood	6.7 × 10^–1	Geddes and Baker (1967)
Bone	1.09 × 10^–2	Akhtari et al. (2002)
Cerebrospinal fluid	1.8	Baumann et al. (1997)
Fat	2.5 × 10^–2	Gabriel et al. (1996)
Gray matter	1.0 × 10^–1	Gabriel et al. (1996)
Muscle	1.6 × 10^–1	Geddes and Baker (1967)
Sclera, lens	5.0 × 10^–1	Gabriel et al. (1996)
Skin	4.3 × 10^–1	Holdefer et al. (2006)
White matter	1.2 × 10^0 (long.)	Geddes and Baker (1967)
	1.2 × 10^–1 (trans.)