Light controlled signaling initiated by subretinal semiconducting-polymer layer in developing-blind-retina mimics the response of the neonatal retina

Abstract

Optoelectronic semiconducting polymer material interfaced with a blind-developing chick-retina (E13-E18) in subretinal configuration reveals a response to full-field flash stimulus that resembles an elicited response from natural photoreceptors in a mature chick retina. The response manifests as evoked-firing of action potentials was recorded using a multi-electrode array in contact with the retinal ganglion layer. Characteristics of increasing features in the signal unfold during different retina-development stages and highlight the emerging network mediated pathways typically present in the vision process of the artificial photoreceptor interfaced retina.

Temporal Characteristics of Neonatal Chick Retinal Ganglion Cell Responses: Effects of Luminance, Contrast, and Color

“…Most of the clustered RGCs were responsive to both increments and decrements in contrasts and, if classified based on the R ON/ R OFF (bias index) metric, can be labeled as ON-OFF cells. (Deepak et al 2022) This bias index metric was also observed to be highly sensitive to ambient illumination (luminance) and pulse width of the full field flash, indicative of integrated processes of the photons/charges generated in the RGC receptive field. More rigorous characterization of cell types was carried out by introducing a full field random flicker stimulus where intensity values were picked from a gaussian distribution with an effective mean luminance value of 7 mW/m 2 and a contrast factor controlled by the variance of the distribution.…”

“…A suitable healthy retina was then removed to a separate bubbled petri dish under a stereo microscope, where it was cut to the desired size and placed on an annularly cut custom nylon mesh with a pore size of 100 μm with the photoreceptor side facing the nylon mesh. (Deepak et al 2022) There are intrinsic difficulties of recording from the chick retina owing to waves of spreading depression after the onset of which the fundamental firing properties of RGCs change and the native response state is nearly impossible to recover. A popular strategy that is employed to prolong the survivability of the explant is the application of the Mg 2+ block by way of increased MgCl 2 in the recording medium and its wash-off prior to the electrophysiological recording.…”

“…(Seifert et al, 2020) The understanding of chicken retina development is beneficial in the context of prosthetics that elicit specific activation of different RGC types. (Deepak et al, 2022)…”

“…(Seifert et al, 2020) The understanding of chicken retina development is beneficial in the context of prosthetics that elicit specific activation of different RGC types. (Deepak et al, 2022) Though there is now a recent wealth of anatomical information available on the chick retina with recent studies done on its connectivity in the outer plexiform layer (Gunther et al, 2021) and solving of the chick transcriptome (Yamagata et al, 2020), there is a scarcity of electrophysiological studies performed on it. The utility of multi-electrode array extracellular recordings on neonatal chick retinal explants to extract the wavelength-dependent response properties of different color -opponent and non-color opponent RGCs is presented.…”