77
spatial response of a single rod.
Figure 5.3 : Estimated space constant of of rod network. (A) Normalized rod response
compared with rod response deconvolved with theoretical isolated rod response from fig-
ure 5.2 D. (B, C) Each side of the deconvolved response fit with a single exponential decay
r - к exp (-æ/(ʌin)). Values of λ of 17.4 and 9.8 μm correspond through equation 5.5 to
7 =0.91 and 3.31, respectively. Assuming an isolated rod membrane impedance Rm ≈ 300
MΩ, these values of gamma predict a coupling resistance Rc of 272 and 994 MΩ.
Figure 5.2D shows the theoretical isolated rod response to the light bar compared to
the actual rod response in the network. The theoretical isolated rod response has a larger
amplitude than the actual response due to an absence of signal spread to coupled rods. Next,