Retina

RGC activity was recorded from isolated retinas of C57BL/6 mice in a pre-symptomatic phase of the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis.
‍
The retinal explant from a CFA (complete Freund’s adjuvant)-treated (control) animal was placed RGC-side down on a MaxOne Chip. The heatmaps represented here depict the activity pattern across the array in terms of amplitude (top) and firing rate (bottom), showing spontaneous RGC spiking recorded across the sample. RGC activity was recorded in dark conditions at room temperature, with the retina maintained in continuously oxygenated AMES medium (USBiological, #A1372). The optic disc and peripheral regions were preserved to ensure axonal integrity. Gentle pressure via the permeable MaxOne Tissue Holder ensures stable electrode contact.
‍
Courtesy of Dr. Filippo Galluzzi, Italian Institute of Technology, Genoa, Italy.

Response to light stimulus of individual foveal RGCs in an ex-vivo human retina from a donor.

Top: Temporally modulated full-field ON/OFF contrast light stimulus used to probe RGC responses.
Bottom: Raster plot showing light-evoked spike responses from individual foveal RGCs. Each row represents a single neuron; each dot marks an action potential. RGCs were functionally classified based on their temporal firing pattern. Cells are grouped and color-coded by response type, reflecting their functional diversity.

Courtesy of Dr. Annalisa Bucci, postdoctoral researcher in the Quantitative Visual Physiology Group led by Dr. Felix Franke at the Institute of Molecular and Clinical Ophthalmology Basel (IOB)

Tracking axonal action potential propagation in RGCs.  

Top: (Left) Human retina isolated and flattened post-enucleation. (Right) Successive frames show action potential traveling along an exemplary axon across the electrode array. The aggregated frames yield the spatial profile of the average action potential waveform along the axonal trajectory.
‍Bottom: (A) Electrical images of representative RGC axons from peripheral (top) and foveal (bottom) regions. Peripheral RGC axons project toward the optic disc in near-linear paths, while foveal RGC axons follow curved trajectories around the foveola. Colored squares indicate electrodes detecting action potentials, with color denoting voltage amplitude. (B) Average action potential wave forms recorded at increasing distances from the soma at the selected sites shown in A as black squares. (C) Axonal action potential propagation speed for the different RGCs in A.

Courtesy of Dr. Annalisa Bucci, postdoctoral researcher in the Quantitative Visual Physiology Group led by Dr.Felix Franke at the Institute of Molecular and Clinical Ophthalmology Basel(IOB).Related to this topic: Bucci et al.,Nature Neuroscience, 2025.