This should facilitate the identification of the corresponding neurons in the fly optic lobe. We recorded extracellular spike trains from the motion-sensitive neuron H1 in 3- to 12-day-old blow flies (Calliphora vicina). Flies were fixed with wax, the head capsule was opened, and air sacks see more and

fat tissue were removed. The head was then aligned to the frontal pseudo-pupils. H1 activity was recorded with a tungsten electrode inserted into the left lobula plate, amplified, band-pass filtered, and recorded at a sampling frequency of 10 kHz. Spikes were detected offline with a threshold operation. The traces depicted in this work were generated by averaging over trials and convolving the result with a Gaussian filter (standard deviation of 5 ms). The visual stimulus was presented on a CRT monitor (M21LMAX; Image Systems Corp., Minnetonka, MN, USA) updated at 240 Hz. For OFF, intermediate, and ON brightness values, we used 1 cd/m2, 14 cd/m2, and 57 cd/m2; the intermediate luminance was chosen such that ON and OFF stimuli yielded responses of similar

amplitudes. The horizontal angular extent of one stripe was set to 3°, the vertical extent amounted to 40°. We used female wild-type Canton-S experimental flies, 1–2 days after eclosion, raised on standard cornmeal-agar medium with a 12 hr light/12 hr dark cycle, 25°C, and 60% humidity. Patch-clamp recordings were performed as described in Joesch et al. PLX-4720 solubility dmso (2008). VS-cell somata covered by ringer solution (Wilson et al., 2004) were approached with a patch electrode filled with a red fluorescent dye (intracellular solution as in Joesch et al. [2008]). Recordings Linifanib (ABT-869) were established under visual control using a 40× water-immersion objective (LumplanF; Olympus), a Zeiss Microscope (Axiotech vario 100; Zeiss, Oberkochen, Germany), and illumination (100 W fluorescence

lamp, hot mirror, neutral density filter OD 0.3; all from Zeiss, Germany). To enhance tissue contrast, we used two polarization filters, one located as an excitation filter and the other as an emission filter, with slight deviation on their polarization plane. For eye protection, we additionally used a 420 nm LP filter on the light path. Visual stimuli were delivered using a custom-built light-emitting diode (LED) arena (Reiser and Dickinson, 2008, Joesch et al., 2008 and Schnell et al., 2010). Horizontal stripes were presented in the front of the fly’s visual field. For the results depicted in Figure 2 and Figure 3, we used stripes covering the complete arena in the horizontal plane and 10° in elevation (either from 0° to +10° or −10° in elevation). The vertical angular extent of the stripe was set to match twice the inter-ommatidial distance. The luminance values used for OFF, intermediate, and ON stimuli were 0 cd/m2, 16 cd/m2, and 64 cd/m2, respectively.