Table 2.

Parameters used in fitting responses for different subjects

Subject	Symbols used in Fig. 3Fig. 10		td(ms)	τ(ms)	−αmax(μV)	A(s−2)	I0(Td)	τequiv(min)	τRh(min)
MMT	•	•	1.8	0.9	242	4.4	42	2.8	13
	•		2.0	0.9	200	5.1	53	—	—
TDL	⋄	⋄	2.1	1.0	319	4.3	42	2.9	10
GW	▪	—	2.1	1.0	301	4.1	80	—	—
CF	▾	▾	2.0	0.9	278	3.6	82	4	15
	▾		2.0	0.9	200	5.2	100*	—	—
FD	▵	▵	1.8	0.9	260	5.8	80	2.25	9.5
AH	▿	—	2.0	0.9	335	3.3	100*	—	—
CC	○	○	2.0	0.9	275	4.8	55	3	13
GS	⋄	⋄	2.0	1.0	340	5.4	60*	3	9
Mean ± S.D.			—	—	275 ± 51	4.6 ± 0.8	69 ± 7	3.0 ± 0.6	11.6 ± 2.4

Identification of symbols used in Figs 3 and 10, together with values of parameters used in fitting curves. t_d is the pure delay, and γ is the membrane time constant, used in the full equivalent of eqn (6). a_max is the maximal amplitude, and A is the amplification constant obtained under dark-adapted conditions. I₀ is the background intensity required to halve a_max in light adaptation experiments.(For experiments marked

^*A was allowed to decrease at high background intensities; see text.) τ_equiv is the time constant for decay of the equivalent background in eqn (9), and τ_Rh is the regeneration time for rhodopsin in eqn (10), in dark-adaptation experiments