Local processing in neurites of VGluT3-expressing amacrine cells differentially organizes visual information

Abstract

Neurons receive synaptic inputs on extensive neurite arbors. How information is organized across arbors and how local processing in neurites contributes to circuit function is mostly unknown. Here, we used two-photon Ca2+ imaging to study visual processing in VGluT3-expressing amacrine cells (VG3-ACs) in the mouse retina. Contrast preferences (ON vs. OFF) varied across VG3-AC arbors depending on the laminar position of neurites, with ON responses preferring larger stimuli than OFF responses. Although arbors of neighboring cells overlap extensively, imaging population activity revealed continuous topographic maps of visual space in the VG3-AC plexus. All VG3-AC neurites responded strongly to object motion, but remained silent during global image motion. Thus, VG3-AC arbors limit vertical and lateral integration of contrast and location information, respectively. We propose that this local processing enables the dense VG3-AC plexus to contribute precise object motion signals to diverse targets without distorting target-specific contrast preferences and spatial receptive fields.

Cell Types of the Human Retina and Its Organoids at Single-Cell Resolution

“…We performed live two-photon laser imaging of organoids, visualizing an optical cross-section that encompassed the outer nuclear, inner nuclear and ganglion cell layers ( Figure 2 H). We stimulated photoreceptors with the two-photon laser used for imaging, which was shown to evoke light responses ( Baden et al., 2013 , 2016 ; Hsiang et al., 2017 ; Ruminski et al., 2019 ). As a control, background activity was measured by continuous two-photon imaging after photoreceptors adapted to the stimulation.…”

Dendritic and parallel processing of visual threats in the retina control defensive responses

“…This could either be due to differences in the size or arrangement of ON and OFF excitatory and inhibitory receptive fields, differences in the kinetics of the underlying mechanisms, or a combination of both. Maps constructed from responses to stationary stimuli indicate that OFF receptive fields of VG3 amacrine cells are smaller than their ON counterparts (22,26,27). The smaller OFF receptive fields explain the faster time to peak excitation for looming versus white looming ( Fig.…”

“…2). This was true across regions of interest (ROIs) with different baseline fluorescence, suggesting that it is not an effect of the calcium indicator (22). Instead, the higher selectivity of dendritic calcium signals likely reflects activation thresholds of voltage-gated calcium channels, which are expressed in VG3 amacrine cells and contribute to transmitter release (27,39).…”

“…Amacrine cells send and receive signals through their dendrites. Thus, one amacrine cell can contain multiple input-output pathways that process information separately, bypassing the soma (22,23,28,29). We used two-photon calcium imaging to analyze motion signals in VG3 dendrite arbors.…”

Diving into the brain: deep-brain imaging techniques in conscious animals

“…The second and more common approach is to generate transgenic animals bearing GCaMP expression in specific cell types, by crossing a Cre-driver with a floxed-GCaMP mouse (Hsiang et al 2017, Zimmerman et al 2019. Several floxed-GCaMP mice lines are now commercially available from Jackson Laboratories and have been characterised by users.…”