, 1999 and Ishikane et al., 2005). Those studies had suggested that these cells detect large approaching objects through synchronized oscillatory activity and thereby this website trigger the frog’s escape

response to dark looming objects. It is conceivable that this detection of slowly approaching objects works in concert with the detection of suddenly appearing large objects proposed in the present study, thus mediating detection of large, potentially threatening objects over a wide range of behavioral scenarios by a single ganglion cell type in the amphibian retina. Inhibitory signaling appears to be critical for both mechanisms, and indeed, it was shown that the frog’s natural escape behavior to large objects is suppressed when inhibition is blocked in the frog’s eyes (Ishikane et al., 2005). The circuit structure proposed to generate the local gain control of homogeneity detectors (Figure 7C) is not unique to the retina. Similar parallel transmission pathways of excitation and inhibition have also been identified elsewhere in the brain (Porter et al., 2001, Pouille and Scanziani, 2001, Gabernet et al., 2005, Sun et al., 2006, Cruikshank et al., 2007, Strowbridge, 2009 and Bellavance et al.,

2010). Measuring iso-response stimuli in these systems by stimulating local subcircuits independently could PD0325901 chemical structure be used to probe their functional roles and the potential implementation

PD184352 (CI-1040) of a similar local gain control. Moreover, we suggest that measurements of iso-response stimuli can function as a general tool to identify the rules of signal integration in a wide variety of neural systems wherever different signaling streams converge onto single neurons. Retinas were isolated from dark-adapted adult axolotl salamanders (Ambystoma mexicanum; pigmented wild-type) and mounted onto 60 channel multielectrode arrays for extracellular recordings of ganglion cell spiking activity. All experimental procedures were performed in accordance with institutional guidelines of the Max Planck Society. During the recordings, retinas were superfused with oxygenated Ringer’s solution at room temperature (20°C–22°C). For experiments with pharmacological inhibition block, strychnine (5 μM), picrotoxin (150 μM), and bicuculline (20 μM) were added to the Ringer’s solution. Visual stimuli were displayed by a gamma-corrected cathode ray tube monitor and focused onto the retina with standard optics. Mean light intensities were in the photopic range, and all stated contrast values correspond to Weber contrast (Istimulus – Ibackground) / Ibackground.