, 2007, Tammero et al., 2004 and Theobald et al., 2010). Work in other arthropods demonstrates that translational and rotational

cues can be independently analyzed to inform distinct behaviors (Collett, 1980, Junger and Dahmen, 1991 and Barnes, 1990). Previous work comparing turning and forward movements in freely walking flies proposed that these two behavioral responses were the products of specialized neural circuits that RG7420 research buy diverge early in the visual system (Katsov and Clandinin, 2008). However, in this previous study, flies experienced complex patterns of optic flow comprising both rotational and translational components, making the extent of this separation unclear. We established a behavioral paradigm in which single walking flies modulated their forward walking speed in response to motion signals without changing their turning, thereby uncoupling these two behavioral responses (Figure 7). Combining this paradigm with specific neuronal manipulations of input channels, both individually

and in combination, we demonstrate that L1, L2, and L3 are required for motion detection, but are individually specialized (Figure 9I). One of these cells, L1, only provides input to motion detectors that guide turning. L2 and L3, on the other hand, provide input both to detectors that guide turning as well as forward walking. Thus, the input pathways that couple turning and forward walking to motion are different. Our data demonstrate that Paclitaxel manufacturer distinct but overlapping combinations of inputs to motion

detecting circuits are tuned to particular stimulus features and linked to specific behavioral outputs (Figure 9I). First, light edge detecting circuits require inputs Bay 11-7085 from L1, while dark edge detecting circuits utilize inputs from L1, L2, and L3. Second, the ability of motion signals to modulate turning responses requires inputs from L1, L2, and L3 (Figures 5 and 6), while the modulation of forward walking speed requires only the inputs of L2 and L3 (Figures 8 and 9). As our data demonstrate, overlapping sets of neurons, each with different physiological properties and connections, are combined into modules that inform different behavioral outputs. Such a combinatorial use of input channels represents an efficient way to generate a variety of coding possibilities using a limited set of neurons. Given that L1, L2, and L3 make a diverse array of synaptic contacts in the medulla, our data also raise the possibility that downstream motion computations are distributed among many different neuron types. Specific subsets of these downstream pathways could then converge in deeper layers of the visual system to tune neurons to particular motion features (de Vries and Clandinin, 2012, Egelhaaf et al., 2002, Hausen, 1982, Krapp et al., 1998 and Mu et al., 2012). These more specialized neurons could then inform specific motor outputs appropriate to the visual stimulus.