Fig. 8.

Spectral sensitivity of dLGN neuron responses under scotopic conditions. (A) Representative responses of a R. pumilio dLGN neuron to 1 s dim light flashes (means of 20 trials) of varying intensity and wavelength under dark-adapted conditions. (B) Irradiance–response relationship for neuron in A with irradiance quantified according to the effective photon flux (photons cm⁻² s⁻¹) for a single opsin with a λ_max of 493 nm (corrected for R. pumilio lens transmission). Inset shows spectral sensitivity estimate (quantified as the percentage variance in effective irradiance–response curves explained by the best-fitting 4-parameter sigmoid curve). (C) Population spectral sensitivity estimates showing the best-fitting single opsin λ_max and corresponding response variance explained (as in B). (D) Normalised mean±s.e.m. irradiance–response relationships for cells whose responses to light intensity (photons cm⁻² s⁻¹) were best explained by a single opsin (>80% variance explained, highlighted in red in C), fitted with 4-parameter sigmoid curves. (E) Sensitivity estimates (from D), fitted to a R. pumilio lens-corrected opsin template with λ_max of 493 nm (R²=0.99).