Fig. 4. Comparison of sensitivities to polarized light and unpolarized light in LoTu1. (A) Intracellular recording traces during stimulation with dorsal polarized blue (450 nm) light (Dors pol-light) at three intensities. (B) Intracellular recording of responses to unpolarized monochromatic light stimuli with increasing intensity. Inhibition to dorsal blue light becomes obvious at logI=–1.5 (arrow); it is followed by rebound excitation (open arrowhead). Ipsilateral UV light at logI=–2 inhibits the neuron (arrowhead). At logI=–1, the neuron is completely inhibited including the inter-stimulus intervals (double open arrowhead). Ipsilateral green light leads to excitation beginning at logI=–2 (double arrowhead). Maximum light intensity for all stimuli (logI=0) was 10.6x10¹² photons cm^–2 s^–1. (C) Intensity/response curves for dorsal polarized blue (450 nm) light at _max (Dors-pol B), dorsal unpolarized blue light (Dors-B), and unpolarized ipsilateral green light (Ipsi-G). The inhibitory responses to Dors-B are shown as normalized values of activity during stimulation minus activity before stimulation for better comparison. Solid lines are fits of Naka–Rushton functions with the fitting parameters rA_max=0.94, K=–3.25 log units, n=1.54 (Dors-pol B), rA_max= 1.03, K=–0.81 log units, n=2.27 (Dors B), and rA_max=1.63, K=–0.23 log units, n=0.88 (Ipsi G). Broken line indicates background activity.