Researchers: Nerve cells of blind mice retain their visual function

(Image credit: Adobe Stock/Abdul)

Often portrayed as the “outpost of the brain,” the retina plays a key role in visual signal processing, performing critical functions that precede higher-order processing in the cerebrum. When light enters the eye, photoreceptor cells within the retina convert it into electrical signals, which are then transmitted to layers of nerve cells and ultimately relayed to the brain.

While the general process of retinal signal transmission is well documented, the specific mechanisms by which retinal nerve cells process these signals have remained an enigma. Researchers at Vienna University of Technology (TU Wien) have recently shed light on this mystery, uncovering intrinsic differences in the signaling patterns of retinal ganglion cells—neurons that transmit visual information to the brain. These findings could significantly advance vision restoration technologies, such as retinal implants for individuals with degenerative eye conditions.¹

Distinct roles of retinal ganglion cells

Paul Werginz, PhD, from TU Wien’s Institute of Biomedical Electronics, explains that electrical signals generated by photoreceptors upon light stimulation are transmitted to nearby nerve cells. However, not all nerve cells exhibit identical electrical activity.

“Certain retinal ganglion cells show reduced activity shortly after being stimulated, while others maintain a higher level of signaling for longer periods,” says Werginz. This variability was surprising, as similar cell types were expected to produce uniform responses.

To address this inconsistency, Werginz and his team investigated whether the differences arose from distinct inputs received by the cells within biological circuits or from inherent biophysical properties unique to each cell type. “If these differences are intrinsic, we can think of each ganglion cell type as having a unique ‘component ID,’” he explains.

Investigating intrinsic properties

The team conducted experiments on explanted mouse retinas, preserving the neuronal network for several hours. By stimulating the retinal ganglion cells either with light or through direct electrical current, they could isolate the cells’ properties from the influence of upstream circuitry.¹

According to Werginz, the results were compelling. “Cells that exhibited prolonged activity in response to light showed similar patterns when stimulated electrically,” he reports. This finding confirms that the differences in signaling behavior are intrinsic to the cells themselves, not merely a product of their inputs.

Implications for vision restoration

An essential question was whether these intrinsic properties persist even when the retina’s photoreceptors are no longer functional. Using retinas from mice that had been blind for 200 days, the researchers discovered that retinal ganglion cells maintained their unique signaling characteristics.

“This is remarkable because, in other parts of the nervous system, nerve cells often reorganize when their original functions are lost,” says Werginz. For example, brain regions that process input from an amputated finger often adapt to serve other purposes.

The stability of retinal ganglion cell properties offers hope for vision restoration strategies. Retinal implants designed to electrically stimulate specific ganglion cell types could harness these intrinsic differences, allowing for more precise and effective signal transmission to the brain.

Advancing retinal prosthetics

“These findings suggest we can build on the inherent stability of ganglion cell signaling to create better retinal implants,” says Werginz. “By targeting specific cell types, we can optimize visual signal processing and improve outcomes for patients with retinal degeneration.”

The study also suggests that these signaling differences arise during early retinal development and remain stable throughout life, even in cases of blindness. This discovery opens exciting possibilities for developing advanced retinal prosthetics capable of restoring meaningful vision.¹

“Understanding the intrinsic properties of these cells gives us a foundation to design innovative approaches to vision restoration,” Werginz concludes. “It’s a significant step toward improving the lives of individuals with degenerative retinal diseases.”

Reference

1. Nerve cells of blind mice retain their visual function. EurekAlert! Published November 26, 2024. Accessed December 3, 2024. https://www.eurekalert.org/news-releases/1066179