Figure 8From: Optical and electrical recording of neural activity evoked by graded contrast visual stimulus⟨Δ[HbO2]⟩ (solid red circle) and ⟨Δ[HHb]⟩ (solid blue square) averaged over observers as a function of stimulus contrast. The bars represent the standard errors (SE) evaluated over the nine subjects whereas the dashed lines represent the best logarithmic fit of the data.Back to article page