The role of starburst amacrine cells in visual signal processing

Abstract

Starburst amacrine cells (SBACs) within the adult mammalian retina provide the critical inhibition that underlies the receptive field properties of direction-selective ganglion cells (DSGCs). The SBACs generate direction-selective output of GABA that differentially inhibits the DSGCs. We review the biophysical mechanisms that produce directional GABA release from SBACs and test a network model that predicts the effects of reciprocal inhibition between adjacent SBACs. The results of the model simulations suggest that reciprocal inhibitory connections between closely spaced SBACs should be spatially selective, while connections between more widely spaced cells could be indiscriminate. SBACs were initially identified as cholinergic neurons and were subsequently shown to contain release both acetylcholine and GABA. While the role of the GABAergic transmission is well established, the role of the cholinergic transmission remains unclear.

Molecular Changes and Vision Loss in a Mouse Model of Closed-Globe Blast Trauma

“…These cells are critical for signaling directional selectivity onto downstream RGCs and are, therefore, necessary for the OKN response that is used to measure visual acuity (see Ref. 38 for review) and damage to them could underlie the decrease in visual acuity and the alterations in the OPs detected after blast in our model. The spread of caspase-1 labeling from small retinal regions at 3 days post blast to amacrine cells throughout the entire retina at 28 days post blast suggests spread of a molecular signal to neighboring cells.…”

Bioinspired Visual Motion Estimation

“…The Barlow-Levick model relies on inhibition instead of excitation as the underlying mechanism, with null direction motion inhibiting a motion unit's response. Although the presence of Hassenstein-Reichardt and Barlow-Levick motion models has been ruled out in macaque, a similar mechanism relying on unbalanced inhibition is thought to underlie directional selectivity of starburst amacrine cells in primate retina [34].…”

“…In Drosophila, motion estimation can still be performed in the L1 (on) pathway if the L2 (off) pathway is blocked, and vice versa. In macaque, directionselective starburst amacrine cells (SACs) [34] can be found in the retina itself, and separate SACs are used to process on and off responses in parallel. Although direction selective, these cells show very limited speed sensitivity, with true velocity-sensitive neurons only found in higher visual areas.…”

A neurociência computacional no estudo dos processos cognitivos

“…There are many studies of vision at the neuronal level that combine morphology, physiology, and computational modeling techniques to investigate how retinal amacrine cells generate direction selectivity in their post-synaptic partners (Masland, 2012b;Taylor & Smith, 2012;Tukker, Taylor, & Smith, 2004). Although the morphological and electrophysiological evidence provides a general explanation of the phenomenon (Taylor, He, Levick, & Vaney, 2000;Taylor & Smith, 2012), only the computational model allows a richer characterization of predictive, and not only descriptive, character (Stuart, Spruston, & Häusser, 2007).…”

“…Although the morphological and electrophysiological evidence provides a general explanation of the phenomenon (Taylor, He, Levick, & Vaney, 2000;Taylor & Smith, 2012), only the computational model allows a richer characterization of predictive, and not only descriptive, character (Stuart, Spruston, & Häusser, 2007).…”