99
current) in the follower cell.
V0 - Rin2D^0 + Rin2D,ilK
- (5.17)
r?l = Rm2DZQK + Rin2Dil
■ l.
From the second relationship, if tq is assumed to be 0 because the follower cell is held at the
rod resting potential then:
Rin2D^l ~ ~Rirι2D∣oR
κ---i-÷-
Divide the first relationship in system 5.17by zi and substitute in K
^7^^ = Rin2D^r^ ~ Rin2D^T- (5.18)
Zl Zi Zo
from our definition of network resistance between adjacent cells (R apparent) Ra = v0∕iι
2o ∕?
Rin2D = 7^-il ■ ⅝ = T---½∙ (5.19)
∖ iɪ io / ∖ iɪ io /
The input impedance for all pairs estimated from equation 5.19 is shown in figure 5.7.
The mean Ri∏2D was 137 MΩ, which is in line with our experience from recording from rod
photoreceptors. Figure 5.9 A shows the estimates of Rin2D for each pair of cells, and figure
5.9 B shows a box plot with the means, 25th and 75th percentiles of the same data.
From the previous set of equations we can also solve for how Ra varies with Ri∏2D and
A2d∙ Substituting K back into equation 5.18 yields
— = Ra = ~RiJK + RinK
• Lt tlt∕ t / t
Zi .