Cellular Inhibitory Behavior Underlying the Formation of Retinal Direction Selectivity in the Starburst Network

Abstract

Optical imaging of dendritic calcium signals provided evidence of starburst amacrine cells exhibiting calcium bias to somatofugal motion. In contrast, it has been impractical to use a dual-patch clamp technique to record membrane potentials from both proximal dendrites and distal varicosities of starburst amacrine cells in order to unequivocally prove that they are directionally sensitive to voltage, as was first suggested almost two decades ago. This paper aims to extend the passive cable model to an active cable model of a starburst amacrine cell that is intrinsically dependent on the electrical properties of starburst amacrine cells, whose various macroscopic currents are described quantitatively. The coupling between voltage and calcium just below the membrane results in a voltage-calcium system of coupled nonlinear Volterra integral equations whose solutions must be integrated into a prescribed model for example, for a synaptic couplet of starburst amacrine cells. Networks of starburst amacrine cells play a fundamental role in the retinal circuitry underlying directional selectivity. It is suggested that the dendritic plexus of starburst amacrine cells provides the substrate for the property of directional selectivity, while directional selectivity is a property of the exclusive layerings and confinement of their interconnections within the sublaminae of the inner plexiform layer involving cone bipolar cells and directionally selective ganglion cells.

Opposing motion inhibits responses of direction-selective ganglion cells in the fish retina

“…In other words, suppression of the preferred-side response by the null-side stripe during the opposing motion of stimuli could be induced by a postsynaptic inhibitory mechanism, similar to that described in the mouse retina (Yonehara et al, 2013). However, results of our study cannot unambiguously exclude involvement of a presynaptic inhibitory mechanism (Euler et al, 2002;Fried et al, 2002Fried et al, , 2005Poznanski, 2005Poznanski, , 2010 in the late phase of opposing motion. Hence, from the all abovementioned one can say that the results of our study leave open the question which of two circuitries underlie null-side inhibitory e®ects described in¯sh DS GCs À À À the one based on the single postsynaptic mechanism or the second based on coordinated pre-and postsynaptic processing.…”

Asymmetric Inhibitory Connections Enhance Directional Selectivity in a Three-Layer Simulation Model of Retinal Networks

“…prediction of the effect of presynaptic feed-back inhibition on directional selectivity [Fried et al, 2005;Borg-Graham, 2001;Poznanski, 2010b]. These mechanisms very possibly also contribute to enhance directional selectivity in real retina.…”

The role of starburst amacrine cells in visual signal processing

“…Reciprocal connections observed between SBACs (Millar & Morgan, 1987) and evidence for tonic GABAergic inhibition of SBACs (Massey & Redburn, 1982) laid the groundwork for the suggestion that directional signals might arise through network interactions involving a plexus starburst cells (Dacheux et al, 2003; Lee & Zhou, 2006; Münch & Werblin, 2006; Enciso et al, 2010; Poznanski, 2010). The central idea is that reciprocal GABAergic connections between opposing dendrites of SBACs produce a positive feedback network that can enhance the asymmetric DS voltage response in the peripheral dendrites of the SBACs.…”