According to published in Neuron .
A peculiar feature of this cell, known as “Burst Contrast Suppression” (bSbC) retinal ganglion Cells (RGCs) overturn decades-old assumptions about the relationship between cell input and output from photoreceptors to the brain, according to Derrick T. Vail Professor of Ophthalmology and senior author Gregory Schwartz, Ph.D.
“The classic view is that these ganglion cells simply integrate their excitatory and inhibitory inputs, which would tell How your cells respond to visual stimuli,” said Schwartz, who is also a professor of neuroscience. “Our findings suggest that these cells have their own intrinsic computing power, which has interesting implications for retinal prostheses and more.”
There are more than 40 RGCs that transmit information about specific and complex features of a visual scene, including motion, orientation, orientation, and color. For example, the “off-sustained alpha” (OFFsA) RGC type has a baseline firing rate, but when light increases, the cells signal less to the brain, and vice versa.
In this study, researchers compared OFFsA and bSbC ganglion cell type pairs Responses to different visual stimuli, recording the resulting signals that will be sent to the brain. The study’s authors found that bSbC has a strange mechanism: a baseline rate at which cells signal to the brain, but both increases and decreases in light lead to decreased signaling, a unidirectional signaling pattern.
“The signal can only go down,” Schwartz said.
In addition, the researchers tested the classical view of how these ganglion cells integrate inputs. These cells receive excitatory and inhibitory signals from photoreceptors in the retina, and popular theories suggest that these inputs combine to reach a certain threshold, causing changes in signal output. To test this, Schwartz and his collaborators swapped the inputs of OFFsA and bSbC ganglion cells with each other and found that the output signal in this experiment was identical to normal activity.
” This means they have their own ion channels that affect the output, their own one Group conductance affects the output,” Schwartz said.
These findings have implications for devices such as retinal prostheses designed to stimulate light that no longer responds to light Reactive RGC. Current prosthetics only produce rough vision, and Schwartz believes part of the problem is that the prosthetics send the wrong signals to the wrong types of cells.
“You can’t turn on the light to check what type of retinal ganglion cells they are because the receptors are damage – that’s a category 22 problem,” Schwartz said.
Conversely, studying the computations inherent in each cell type can help scientists identify which cells are which, even if not correct photoreceptor input.
” If you can get detailed information about these onboard calculations, you might be able to send each cell type The right signal,” Schwartz said.
More info: Sophia Wienbar et al. Differences in spike generation rather than synaptic input determine two Feature selectivity in retinal cell types, neurons (2022). DOI: 10.1016/j.neuron.2022.04.012
Citation : New insights into retinal neurons (August 5, 2022) Retrieved August 24, 2022 from https://medicalxpress.com/news/2022-08-insights-retinal-neurons.html
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