On-Off Direction-Selective Ganglion Cell

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Image of an On-Off Direction-Selective Ganglion Cell[1]

Direction selective (DS) cells in the retina are defined as neurons that respond differentially to the direction of a visual stimulus. The term is used to describe a group of neurons that "gives a vigorous discharge of impulses when a stimulus object is moved through its receptive field in one direction" [2]. There are three known types of DS cells in the vertebrate retina of the mouse, ON/OFF DS ganglion cells, ON DS ganglion cells, and OFF DS ganglion cells. Each has a distinctive physiology and anatomy[3]. The rest of this page will only apply to ON/OFF DS Ganglion Cells. There are also ON DS Ganglion Cells (which respond to the leading edge of a stimulus) and OFF DS Ganglion Cells (which respond only to the trailing edge of a stimulus).


ON/OFF DS ganglion cells act as local motion detectors. They fire at the onset and offset of a stimulus (a light source). If a stimulus is moving in the direction of the cell’s preference, it will fire at the leading and the trailing edge. Their firing pattern is time-dependent and is supported by the Reichardt- Hassenstain model, which detects spatiotemporal correlation between the two adjacent points.

The model consists of two symmetrical subunits. Both subunits have a receptor that can be stimulated by an input (light in the case of visual system). In each subunit, when an input is received, a signal is sent to the other subunit. At the same time, the signal is delayed in time within the subunit, and after the temporal filter, is then multiplied by the signal received from the other subunit. Thus, within each subunit, the two brightness values, one received directly from its receptor with a time delay and the other received from the adjacent receptor, are multiplied. The multiplied values from the two subunits are then subtracted to produce an output. The direction of selectivity or preferred direction is determined by whether the difference is positive or negative. The direction which produces a positive outcome is the preferred direction.

In order to confirm that the Reichardt-Hassenstain model accurately describes the directional selectivity in the retina, the study was conducted using optical recordings of free cytosolic calcium levels after loading a fluorescent indicator dye into the fly tangential cells. The fly was presented uniformly moving gratings while the calcium concentration in the dendritic tips of the tangential cells was measured. The tangential cells showed modulations that matched the temporal frequency of the gratings, and the velocity of the moving gratings at which the neurons respond most strongly showed a close dependency on the pattern wavelength. This confirmed the accuracy of the model both at the cellular and the behavioral level [4].

The classical receptive field of the ON–OFF DSGC exhibits center-surround structure, with the size of the receptive field center matching well with its dendritic diameter [6–8]. When presented with a moving bar visual stimulus, both the ON and OFF components of the spike response are direction-selective over a wide range of movement velocities [2]. Furthermore, motion stimuli restricted to a small fraction (<20% in rabbit) of the receptive field can produce directional spiking of ON–OFF DSGCs, indicating that direction-selective mechanisms are present in local dendritic computational subunits that repeat in an array over the DSGC dendritic arbor [5].

The direction in which a set of neurons respond most strongly to is their “preferred direction.” In contrast, they do not respond at all to the opposite direction, “null direction.” The preferred direction is not dependent on the stimulus- that is, regardless of the stimulus’ size, shape, or color, the neurons respond when it is moving in their preferred direction, and do not respond if it is moving in the null direction.

ON/OFF DS ganglion cells can be divided into 4 subtypes differing in their directional preference, ventral, dorsal, nasal, or temporal. The cells of different subtypes also differ in their dendritic structure and synaptic targets in the brain. The neurons that were identified to prefer ventral motion were also found to have dendritic projections in the ventral direction.


Visual response properties

Cellular biophysics


The anatomy of ON/OFF cells is such that the dendrites extend to two sublaminae of the inner plexiform layer and make synapses with bipolar and amacrine cells. They have four subtypes, each with own preference for direction.

The colored objects in panel a are six DSGCs reconstructed by the researchers. The circles are representations of the cell bodies, and the lines are "skeletons" of the dendrites. Each DSGC is said to be "bistratified," which means that its dendrites branch out in two sublayers ("strata") of the IPL. The total number of strata in the IPL is estimated to be around ten. A view of the bottom of the sandwich (panel b) shows the branching of the DSGC dendrites.

Reconstructed ganglion and amacrine cells.



Reconstructed by Omni Desktop from Helmstaedter's skeleton
File:DSGC Brigmann.jpg
Cells and synapses reconstructed from serial block face electron microscopy data. A single starburst amacrine cell (yellow, note synaptic varicosities) and two direction-selective ganglion cells (green). Even though there is substantial dendritic overlap with both cells, all connections (magenta) go to the right ganglion cell. ©Kevin Briggman. New microscope decodes complex eye circuitry: Retinal ganglion cells can recognise directions thanks to amacrine cells[6]


TODO: DS ON/OFF ganglion cells receive excitatory input from bipolar cells but also from the previously mentioned starburst cells (Figure 5A), which are also known as cholinergic amacrine cells (Famiglietti, 1983,Masland and Mills, 1979). Besides ACh, starburst amacrine cells (SACs) also release GABA (Brecha et al., 1988,Masland et al., 1984b,Vaney and Young, 1988) and provide DS ganglion cells with inhibition as well (Figure 5A). In addition, the DS ganglion cells receive both GABA and glycinergic inhibition from other amacrine cell types (reviewed in Dacheux et al., 2003).

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Connections to SAC


ON/OFF DS ganglion cells can be divided into 4 subtypes differing in their directional preference, ventral, dorsal, nasal, or temporal. The cells of different subtypes also differ in their dendritic structure and synaptic targets in the brain. The neurons that were identified to prefer ventral motion were also found to have dendritic projections in the ventral direction. Also, the neurons that prefer nasal motion had asymmetric dendritic extensions in the nasal direction. Thus, a strong association between the structural and functional asymmetry in ventral and nasal direction was observed. With a distinct property and preference for each subtype, there was an expectation that they could be selectively labeled by molecular markers. The neurons that were preferentially responsive to vertical motion were indeed shown to be selectively expressed by a specific molecular marker. However, molecular markers for other three subtypes have not been yet found [7]. (NEED TO ADD SPECIFIC MARKER)




Levick and Barlow performed many of the early experiments related to direction selectivity during the 1960s using rabbit retina [2]

Some of the keyfindings in the rabbit retina have been confirmed in the turtle retina (Marchiafava 1979; Ariel and Adolph 1985; Rosenberg and Ariel 1991; Kittila and Granda 1994; Smith et al. 1996; Kogo et al. 1998), indicating that similar mechanisms may underlie the generation of direction selectivity in diverse vertebrate retinas. In the rabbit retina, there are two distinct types of DS ganglion cells (Barlow et al. 1964). The numerous physiological and morphological studies on vertebrate DS ganglion cells have been most recently reviewed by Amthor and Grzywacz (1993a), who placed special emphasis on the spatiotemporal characteristics of the excitatory and inhibitory inputs to the On-Off DS cells.

Although the actual neuronal circuitry that underlies the generation of direction selectivity in the retina has yet to be elucidated, the diverse models that have been proposed over the last 35 years provide guideposts for future experiments (Barlow and Levick 1965; Torre and Poggio 1978; Ariel and Daw 1982; Koch et al. 1982; Grzywacz and Amthor 1989; Vaney et al. 1989; Oyster 1990; Vaney 1990; Borg-Graham and Grzywacz 1992; Grzywacz et al. 1997; Kittila and Massey 1997). These models are judged primarily by their ability to account for the detailed functional properties of the DS ganglion cells, but this is only one of the requirements. Morphological and biophysical constraints also pose hurdles for candidate mechanisms. For example, it would not be appropriate to require a higher density of a particular neuronal type than is known to exist. Nor would it be sound to postulate highly localised synaptic interactions on dendritic segments where the electrotonic properties indicate more extensive interactions. Finally, the developmental requirements need to be kept in mind: it should be possible to achieve the appropriate specificity in the neuronal connections by such mechanisms as Hebbian-type synaptic modification or the selective expression of marker molecules

Open questions / status / relevance to eyewire

Cells are available for tracing in Eyewire, although these cells are not currently available (March 2012). See http://wiki.eyewire.org/wiki/E2198


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  3. "Motion Sensing in Vision." Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/wiki/Motion_Sensing_in_Vision (Accessed April 02, 2012).
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