Table 1. Glossary of symbols.

Symbol	Parameter	Value	Unit
c	Contrast	Variable	None
g cen	Centre mechanism contrast sensitivity	62	mV contrast-unit−1
g cort	Intracortical gain	1	None
	Geniculocortical gain	4.21 (2 channels); 1.47 (6 channels)	None
g sur	Surround mechanism contrast sensitivity	48	mV contrast-unit−1
g rect	Gain of generator function	7.2	Hz/mV
i	Index of sub-cortical channel	1, 2, …, m	None
m	Number of sub-cortical channels	Variable	None
ni	Sign of ith sub-cortical channel	1 (on-channel); −1 (off-channel)	None
ωs	Stimulus spatial frequency	Variable	radians/deg
ωt	Stimulus temporal frequency	2π×2	radians/s
	Generator potential	Variable	mV
	Static polarisation, cortical stages 2, 3	0.646	mV
	Static polarisation, cortical stage 1	−25.5 (x = y = 0)	mV
	Generator potential in ith sub-cortical channel	Variable	mV
	Sub-cortical static polarisation	1.94	mV
	Static polarisation	Variable	mV
ϕ	Spatial phase	Variable	radians
r cen	Radius of centre mechanism	0.4	deg
r cort	Radius of cortical convergence	2.8	deg
r sur	Radius of surround mechanism	1.1	deg
t	Time	Variable	s
τ cort	Time constant of cortical cells	10	ms
τi	Time constant in ith sub-cortical channel	τ on (on-channel); τ off (off-channel)	ms
τ off	Time constant of off-centre cells	9	ms
τ on	Time constant of on-centre cells	11	ms
θ	Stimulus orientation	Variable	radians
x	Horizontal position in visual field	Variable	deg
xi	Horizontal position of channel i	Variable	deg
y	Vertical position in visual field	Variable	deg
yi	Vertical position of channel i	Variable	deg
z	Index of processing stage	1, 2, …, 7	None

The table provides a glossary of symbols used in this paper. Values are given to three significant places.