(A) Discriminandum viewed at an oblique angle (top) and exactly from the front (bottom), the latter approximating the perspective of the rat. (B) Schematic of the orientations of the stimuli and rule of the categorization task. 0°–45° (red) rewarded as ‘horizontal’ and 45°–90° (solid green) rewarded as ‘vertical.’. (C) Sequential steps in the behavioral task. Each trial started with a head poke that interrupted a light beam and triggered the opening of an opaque gate, followed by visual access to the object. After probing the stimulus, the rat turned its head toward one spout, in this illustration left for vertical and right for horizontal. See Figure 1—figure supplement 1 for the experimental setup. (D) Irradiance for each LED, measured by a spectrometer at the stimulus delivery area. Equivalent photon count values are shown in Figure 1—figure supplement 2. Integrating the power under the curves at wavelengths <580 nm reveals that the infrared LEDs emitted from 2 to 50 times higher intensity as compared to red LEDs, in spite of the infrared LEDs being centered at longer wavelengths (infrared 854 nm and 930 nm LEDs emitted 1.95 and 0.48 mW/cm2, respectively, while red 626, 652, and 729 nm LEDs emitted 0.12, 0.28, and 0.04 mW/cm2, respectively). See Figure 1—figure supplement 3 for normalized irradiance for each LED along with rat’s photopigment spectral sensitivity. (E) Pale curves give the performance of four rats under white light. Dark data points and curves show the average over all rats. Error bars are 95% binomial confidence intervals. See Figure 1—figure supplement 1A for the experimental setup.
© 2018, Nikbakht et al. Figure 1A-C has been reproduced from Figure 1 of Nikbakht et al., 2018, under the terms of the Creative Commons Attribution - NonCommercial - NoDerivs (CC BY-NC-ND 4.0) license.