A couple of months ago I wrote a news release about a Nature Neuroscience study carried out under the direction of Stanford neuroscientist Andy Huberman, PhD. The study, which achieved the first-ever restoration of vision in living mammals, understandably generated a lot of publicity -- there's been no previous demonstration of regrowth of severed optic nerve fibers all the way back to their target destinations in diverse areas of the brain, much less of these fibers' appropriately reconnecting to those sites and transmitting useful visual information to them.
In that study, the scientists treated mice whose optic nerves were badly damaged with both intensive high-contrast visual stimulation and gene therapy. While the latter component means biomedical scientists will have to proceed with caution in translating this discovery into clinical trials, the demand for a vision therapy along these lines is enormous.
Glaucoma, which affects nearly 70 million people worldwide, is caused by excessive pressure on the optic nerve -- essentially the same kind of damage relieved by the manipulations in Huberman's study. Huberman told me the other day that he's received thousands of queries from people interested in participating in a clinical trial. I believe him, as I've routed a few dozen of those queries to him myself.
Now, the National Eye Institute has awarded Huberman, in conjunction with principal investigator Stanford ophthalmology chair and optic-nerve-regeneration researcher Jeff Goldberg, MD, PhD, and colleagues at Harvard and La Jolla, Calif.-based Scripps Research Institute, a three-year grant of upwards of $2 million to take this line of research to the next level.
While the Nature Neuroscience study did succeed in restoring some aspects of vision in mice, that restoration wasn't complete. For example, the mice were able to detect expanding dark circles overhead, suggestive of an approaching winged predator. But they couldn't perform tasks requiring finer visual discrimination.
Huberman thinks that's because the treatment succeeded in regenerating only a couple of the 30 or so subtypes of ganglion cells (which relay visual signals from retina-based photoreceptor cells to the brain via the optic nerve) to a significant extent. The goal now, Huberman says, is to find out what the regeneration-ready ganglion-cell subsets have that the others don't (or vice versa) and then to start coaxing those "foot-dragging" ganglion-cell subtypes into more robust responses to treatment.
You could say Huberman has a vision.
Previously: Long-distance eye-brain connections, partial vision restored for first time ever in a mammal, Double vision: How the brain creates a single view of the world and To maintain good eyesight, make healthy vision a priority
Photo by Norbert von der Groeben
