Cone signals in monostratified and bistratified amacrine cells of adult zebrafish retina

Abstract

Strata within the inner plexiform layer (IPL) of vertebrate retinas are suspected to be distinct signaling regions. Functions performed within adult zebrafish IPL strata were examined through microelectrode recording and staining of stratified amacrine types. The stimulus protocol and analysis discriminated the pattern of input from red, green, blue, and UV cones as well as the light-response waveforms in this tetrachromatic species. A total of 36 cells were analyzed. Transient depolarizing waveforms at ON and OFF originated with bistratified amacrine types, whose dendritic planes branched either in IPL sublaminas a & b, or only within sublamina a. Monophasic-sustained depolarizing waveforms originated with types monostratified in IPL s4 (sublamina b). OFF responses hyperpolarized at onset, depolarized at offset, and in some cases depolarized during mid-stimulus. These signals originated with types monostratified in s1 or s2 (sublamina a). Bistratified amacrines received depolarizing signals only from red cones, at both ON and OFF, while s4 stratified ON cells combined red and green cone signals. The s1/s2 stratified OFF cells utilized hyperpolarizing signals from red, red and green, or red and blue cones at ON, but only depolarizing red cone signals at OFF. ON and OFF depolarizing transients from red cones appear widely distributed within IPL strata. “C-type” physiologies, depolarized by some wavelengths, hyperpolarized by others, in biphasic or triphasic spectral patterns, originated with amacrine cells monostratified in s5. Collectively, cells in this stratum processed signals from all cone types.

What the Zebrafish’s Eye Tells the Zebrafish’s Brain: Retinal Ganglion Cells for Prey Capture and Colour Vision

“…Similarly, r2 exhibited three distinct temporal profiles across red (biphasic), green (weakly biphasic) and blue (monophasic). Accordingly, spectral information was not only encoded through variations in gain and polarity of RGC responses but was in addition mixed with temporal informationreminiscent of a previous similar observation in adult zebrafish amacrine cells (Torvund et al, 2017) as well as in the locust visual system (Osorio, 1986(Osorio, , 1987.…”

“…5B, groups 3, 6, 7, 9, 10). Together, this hints at the presence of extensive further processing of spectral information beyond BCs, possibly involving spectrally diverse ACs (Torvund et al, 2017). We next wondered how this spectral information in the retinal output might map onto functional RGC types.…”

Color Processing in Zebrafish Retina

“…Many larval AC types are also present in adults, as determined by dye (Connaughton et al, 2004 ) and/or immunolabeling (Marc and Cameron, 2001 ; Yazulla and Studholme, 2001 ; Arenzana et al, 2006 ; Yeo et al, 2009 ; Jang et al, 2011 ). These cells exhibit narrow, medium, or wide field dendritic arbors (Jusuf and Harris, 2009 ; Lewis et al, 2015 ) and are widely distributed over the entire retina (Yeo et al, 2009 ; Torvund et al, 2017 ); although it appears the density of parvalbumin s4, and tyrosine hydroxylase (dopaminergic) types is greater in temporal-ventral, or ventral retina than nasal retina (Yeo et al, 2009 ; Jang et al, 2011 ). In adult zebrafish, AC light responses are either transient or sustained, with excitation observed at light ON, light OFF, or both light ON and light OFF (Torvund et al, 2017 ).…”

“…These cells exhibit narrow, medium, or wide field dendritic arbors (Jusuf and Harris, 2009 ; Lewis et al, 2015 ) and are widely distributed over the entire retina (Yeo et al, 2009 ; Torvund et al, 2017 ); although it appears the density of parvalbumin s4, and tyrosine hydroxylase (dopaminergic) types is greater in temporal-ventral, or ventral retina than nasal retina (Yeo et al, 2009 ; Jang et al, 2011 ). In adult zebrafish, AC light responses are either transient or sustained, with excitation observed at light ON, light OFF, or both light ON and light OFF (Torvund et al, 2017 ). Most dendritic branching patterns are highly planar and narrowly restricted to single strata within the IPL.…”

“…ON-OFF responses in zebrafish are characteristic of all bistratified ACs (Figures 6A,B ). Most of these have processes in both IPL sublamina a and b , though some ON-OFF cells have processes bistratified only within sublamina a (Torvund et al, 2017 ). These cells respond to spectral stimuli ranging from 330 nm to 650 nm; however, modeling of their responses indicates virtually exclusive input from red cones (Torvund et al, 2017 ), both at light ON and light OFF.…”