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Then, in 2000, neuroscientist Anthony
Hannan at the University of Melbourne in
Australia decided to spice up the lives of his
lab mice. Inspired by research that showed
enrichment could spark the growth of new
neurons, he provided the rodents with
cardboard for making nests, brightly colored balls for play, and ladders and ropes
to climb. Remarkably, the animals were
much slower to develop symptoms of a
Huntington-like disease than their counterparts in standard housing—the first demonstration that enrichment could significantly
influence neurological disorders.
“Before we did this work, everyone
thought Huntington’s was 100% genetic,”
says Hannan, whose team has gone on to
show similar results in rodent models of autism, depression, and Alzheimer’s disease.
In the past decade, a growing body of work
has suggested that rodents and other animals
have complex mental lives and can experi-
ence a range of emotions once only attrib-
uted to people. Scientists have learned more
about the power of enrichment, too. In 2010,
cancer biologist Lei Cao—inspired by a family
member who had died of cancer—wondered
whether she could combat it by looking be-
yond drugs or genes. Her team at OSU cre-
ated a 1-square-meter enclosure filled with
so many mazes, running wheels, and bright
red, blue, and orange igloos that her daugh-
ter dubbed it “Disneyland for Mice.”
When injected with cancer cells, ani-
mals housed there developed tumors
80% smaller than those in control mice,
or no tumors at all. Cao even discovered
a possible mechanism: A stimulating en-
vironment seemed to activate the brain’s
hypothalamus, which regulates hormones
that affect everything from mood to can-
cer proliferation. “We showed that there’s a
hard science behind enrichment,” she says.
“You can’t just treat the body—you have to
treat the mind.”
Such findings fit with what we know
about how we ourselves respond to our en-
vironment. Stress, depression, and lack of
social support can boost the risk of cancer
in people, and less active individuals are
more likely to develop diseases like Hun-
tington later in life.
In the past few years, a host of other
studies has demonstrated the power of
enrichment. Giving rodents and other
animals toys, exercise, and companions
appears to reduce their susceptibility to
epilepsy, multiple sclerosis, and addiction.
Research published last year showed that
enrichment helps mice fight infections and
sharpens rats’ memories.
The growing literature inspired the National Research Council to update its guide
in 2011. Like similar guidelines in Europe,
it states that all naturally social species
should be socially housed if possible, and
advocates enrichment for all lab animals,
not just nonhuman primates.
Yet scientists can avoid these guidelines
if they successfully argue that enrichment
will compromise their studies, and universities vary in how they apply enrichment.
Showing that enrichment produces happier, healthier lab animals is, after all, not
the same as demonstrating that it yields
better science. Some researchers want
more evidence that enrichment boosts the
quality of experimental results.
“My mind could be changed by good sci-
ence,” Godbout says. “If someone comes
out with clear-cut data that enrichment
impacts the kind of work we do, then of
course we’d follow it.”
That’s what efforts like the fish experi-
ment at UM are trying to provide.
BACK IN THE AQUATIC SUITES, veterinarian
That’s the goal of the university’s Refinement & Enrichment Advancements Laboratory
(REAL), an unusual program
Lofgren co-founded in 2014.
REAL’s team of vets and animal
care technicians aims to “
understand the lived experience
of the animal,” she says, and to
nurture what it has evolved to
do. The marbles, for example,
might reduce the fish’s anxiety
by making the tank feel a bit
more like the wild. (They’re also
easier to clean than gravel.)
Stress can affect a wide range of
physiologies and behaviors, and researchers are beginning to test whether the additions make the animals better models
for depression—and, in the case of these
particular fish—retinal regeneration. “If
we provide subpar welfare,” Lofgren says,
“we are also providing subpar science.”
Across campus, she and her team are
also trying to improve the lives of rabbits. In a fancy, heavily glassed building
once owned by biotech giant Pfizer sits a
room filled with 50 white bunnies in metal
cages the size of large laundry baskets.
A fish at the University of Michigan in Ann Arbor gets to choose between an empty tank and one filled with marbles.