The first reports of DS neurons in the vertebrate retina appeared in the 1960s (for references see Wyatt and Daw, 1975). In particular, an elegant series of papers by Barlow, Levick, and coworkers (e.g., Barlow and Hill, 1963, Barlow et al., 1964 and Barlow and Levick, 1965) on
DS ganglion cells in the rabbit retina initiated more than 40 years of research that established the retinal DS circuitry as one of the most investigated and best understood neuronal circuitries in the vertebrate Bortezomib manufacturer brain. The first type of retinal DS ganglion cells fires both at the leading and the trailing edge of a stimulus moving along the preferred direction through the receptive field (Barlow and Levick, 1965). In other words, a bright spot on a dark background evoked very similar DS responses as a dark spot on a bright background. Due to this contrast independence, this cell type is referred to as ON/OFF DS ganglion cell (for review, see Masland, 2004 and Vaney et al., 2001). They have a distinct morphology with loopy dendrites (Figure 3A; Amthor et al., 1984 and Amthor et al., 1989) ramifying in both the ON and the OFF sublamina of the inner plexiform layer (IPL) (Figure 3D, red cell). The two
arborizations can differ in size and shape (Oyster et al., 1993 and Vaney, 1994), suggesting that the ON and the OFF DS circuits GDC-0068 molecular weight work independently. ON/OFF DS ganglion cells are inhibited by synchronous motion outside their receptive field center and are, thus, sensitive to motion contrast (Chiao and Masland, 2003). As a result of their response properties, ON/OFF ganglion cells are considered to be local motion detectors. They display a rather broad tuning
in both the temporal and spatial frequency domain (see e.g., Figure 2 in Grzywacz and Amthor, 2007). Nevertheless, they seem to be tuned to the temporal frequency of the stimulus rather than to its velocity, speaking in favor of the Reichardt detector as an appropriate description of the underlying mechanism. ON/OFF DS cells can be clustered into four functional subtypes (Oyster and Barlow, 1967), each of which preferring a different motion why direction roughly parallel to the dorsal-ventral (superior, inferior) or nasal-temporal (anterior, posterior) axis (Figure 3D, bottom). A second type of DS cell responds to only the leading edge of a bright stimuli moving on a dark background and is, therefore, referred to as an ON DS ganglion cell. They are monostratified (Figure 3B), and their dendritic arborization ramifies in the inner (ON) sublamina of the IPL (Figure 3D, blue cell) (Amthor et al., 1989, Buhl and Peichl, 1986 and He and Masland, 1998). In contrast to ON/OFF DS cells, ON DS cells respond best to global motion (Wyatt and Daw, 1975) and are tuned to lower temporal frequencies (Grzywacz and Amthor, 2007).