D (μm) | Δϕ≈Δρ (degrees) | l (μm) | Δt (ms) | Q | Q_{pool} | C_{pool} (%) | |
---|---|---|---|---|---|---|---|
AMEs | 470±2.3 (N=8) | 2.5^{*} | 82±0.8 (N=8) | 56±5.5 (N=12) | 1.1 (0.5–1.9) | 102 (45–173) | 10 (8–15) |
ALEs | 330±2.1 (N=9) | 2.15±0.03 (N=40) | 48±0.4 (N=9) | 63±3.3 (N=12) | 0.5 (0.3–1.0) | 47 (23–90) | 15 (11–21) |
PMEs | 280±1.3 (N=8) | 3.34±0.06 (N=40) | 52±0.2 (N=8) | 48±2.2 (N=16) | 0.7 (0.4–1.2) | 67 (33–108) | 12 (10–18) |
PLEs | 430±2.1 (N=6) | 2.10±0.03 (N=40) | 47±0.2 (N=6) | 56±2.6 (N=12) | 0.7 (0.5–1.1) | 67 (41–79) | 12 (10–16) |
Calculations (see Appendix 1) are based on the tabulated optical values: D, lens diameter; Δρ, acceptance angle; l, rhabdom length; Δt, integration time; other values are given in Appendix 1 (means ± s.e.m.). Integration time was taken as the half-width of electrophysiologically measured impulse responses. For ALEs (anterior lateral eyes), PMEs (posterior median eyes) and PLEs (posterior lateral eyes), which all have reflecting tapeta, the morphological rhabdom length l was doubled in the calculation. (AMEs, anterior median eyes.) Quantum catch for spatiotemporal pooling, Q_{pool}, assumes groups of 3×3×3 rhabdoms in a hexagonal array, and a 10-fold increase in integration time. The minimum detectable contrast C_{pool} is calculated as the signal difference that can just overcome quantum noise (square-root of Q_{pool}). For Q and C values the ranges in parentheses are calculated from the measured minimum and maximum values of D, and the upper and lower bounds of standard deviation of Δϕ, l andΔ t. ^{*}Calculated from anatomical data (see Materials and methods)