“if you want to really restore normal vision, you have
to know the retina’s code.” — SheiLA NireNBerg
A new retinal prosthetic creates an
image (middle) that more accurately
reconstructs a baby’s face (left) than
does the standard approach (right).
A new way that the blind might see
Prosthetic retina can turn neural inputs into clearer images
edges, but miss much of a scene.
Many scientists are intent on boost
ing retinal prosthetics’ power. But the
new work suggests that a second, under
appreciated area is also important: the
pattern of cell activity in the retina.
Normally cells that respond to light,
called photoreceptors, pick up signals
and transfer that information as nerve
impulses to ganglion cells. These cells
process the information further and
relay it to the brain, where the scene is
constructed. Spotting a dog creates a
particular code, for example, different
By Laura Sanders
A new type of prosthetic eye may allow
the estimated 25 million people world
wide who have lost sight due to retinal
diseases to someday see the broad sweep
of an ocean or the dimples of a baby’s face.
Sheila Nirenberg of the Weill Medical
College of Cornell University in New
York City presented data November 13
showing that the new retinal prosthetic
allowed blind mice to see a baby’s face.
Current prosthetics can reproduce
simple features, such as bright spots or
from the code for a teacup or a baby’s
face. When a retina is degenerated, the
photoreceptor cells die and there is no
message to send.
Stroke damage
halted by a tickle
rat study suggests sensory
stimulation can protect brain
By Laura Sanders
In the twohour window after a stroke,
a flick of a single whisker prevents many
damaging effects in a rat, a new study
finds. The cheap, simple intervention,
described November 15, may represent
a new way to minimize disability after a
stroke in people.
“It’s almost too good to be true,”
said neuroscientist Carol Barnes of the
University of Arizona in Tucson. “Any
protection would be good, but this is
more than dramatic.”
Researchers led by Ron Frostig of the
University of California, Irvine mimicked
a stroke by severing a major blood ves
sel in rats’ brains. Then at times during
the two hours immediately afterward, a
mechanical rod stimulated a single whis
ker on the anesthetized rat for a total of
less than five minutes.
With whisker stimulation, blood got
rerouted through other vessels, ulti
mately reaching the brain area that
would have been deprived of blood,
Frostig reported. No such rerouting was
present in rats that didn’t have a whisker
stimulated, or in rats that had whisker
stimulation more than two hours after
the stroke. The team’s preliminary data
suggest that the method works for con
scious rats, too.
Brain imaging later found no evi
dence that a stroke had even occurred
in the whiskerbrushed rats. “I have
looked at these images for 20 years, and
I cannot tell you that this animal went
through a major trauma,” Frostig said.
“It looks exactly the same” as scans of
healthy rats.
