, 2006).

In this way, the LN model has found a large number of applications, including assessments of spatial and temporal receptive field properties (Field and Chichilnisky, 2007), classification of different ganglion cell types (Segev et al., 2006, Field and Chichilnisky, 2007, Farrow and Masland, 2011 and Marre et al., 2012), find more and characterization of contrast adaptation (Kim and Rieke, 2001, Baccus and Meister, 2002 and Zaghloul et al., 2005). For more complex stimuli, including natural images and movies, more elaborate techniques exist for matching LN models to data, based on information theory or maximum-likelihood methods (Paninski, 2003, Paninski, 2004, Sharpee et al., 2004 and Pillow and Simoncelli, 2006). Furthermore, the basic form of the LN model has further been extended by including explicit spike generation dynamics together with feedback effects of the cell’s own spiking activity (Keat et al., 2001 and Pillow et al., 2005) as well as interactions between nearby ganglion cells (Pillow et al., 2008). These models have been shown to often provide reasonable predictions of a ganglion cell’s spiking responses, at least under the particular type of white-noise stimulation

used for obtaining the model parameters. The spatio-temporal version of the LN model has even been shown to be a promising starting point for improving the activity patterns of ganglion cells in prosthetic approaches (Nirenberg and Pandarinath, 2012). Yet, in all these versions of the LN model, it is the linear Icotinib supplier filter stage that accounts for

stimulus integration. Thus, stimulus integration is implicitly assumed to be linear under these approaches. This leads one to ask how well the LN model actually works as a framework for capturing the spatio-temporal response properties of ganglion cells, in particular for cells that show nonlinear spatial integration. First, it is important to note that the linear spatio-temporal filter obtained by a spike-triggered-average analysis typically provides accurate information about the receptive field shape even though nonlinearities within the receptive field are not accounted for by the LN model. Beyond characterizing the receptive field, however, the question arises how well the obtained LN model can be used for predicting the spiking response first of a ganglion cell. The general lore appears to be that LN models can yield reasonable predictions when probed with the same type of spatially coarse, temporally broad-band noise stimuli as used for fitting the model, whereas accurate predictions of responses to natural stimuli have remained elusive (Schwartz and Rieke, 2011). One reason for this may lie in the fact that natural stimuli contain spatial correlations in the stimulus (Ruderman and Bialek, 1994) as well as abrupt transitions, owing to the presence of objects and their boundaries.