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Published online:
11 August 2004; | doi:10.1038/news040809-10
Gene therapy cures monkeys of lazinessHelen
Pilcher
Switching off
key gene turns layabout primates into keen workers.
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Monkey tend to slack off just
like humans. ©
Punchstock | | Procrastinating primates can be
turned into workaholics, thanks to gene therapy. The
discovery, which sheds light on the workings of the brain's
reward centre, may further our understanding of mood
disorders, such as depression and obsessive-compulsive
disorder.
Like many humans, monkeys tend to
slack off when their goal is distant, then work harder as a
deadline looms. But when a key gene is turned off, the
primates work hard from the word go, researchers report in
PNAS Online1.
"The
gene knockdown triggered a remarkable transformation in the
simian work ethic," says Barry Richmond of the National
Institute of Mental Health in Bethesda, Maryland, who studied
the animals.
Richmond's team trained four
monkeys to release a lever when a spot on a computer screen
turned from red to green. The animals had to complete several
trials correctly before they received a reward. To give them
an idea of how many trials were left, a grey bar on the screen
became progressively brighter as the task
progressed.
 The monkeys became extreme
workaholics. This was conspicuously
out-of-character for these animals  |
Barry Richmond
National Institute of Mental
Health, Bethesda,
Maryland | | |
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| The team then injected a short strand of DNA into
each monkey's brains, temporarily switching off a key gene in
a region of the brain called the rhinal cortex, which is known
to be involved in processing reward signals. The gene encodes
a protein called a D2 receptor that makes nerve cells more
sensitive to dopamine, a chemical that is also implicated in
the perception of reward.
With the gene turned
off, the monkeys were unable to anticipate how many trials
were left before the reward was given. They stopped
procrastinating and worked hard throughout the task, making
consistently fewer errors at every stage.
"The
monkeys became extreme workaholics," says Richmond. "This was
conspicuously out-of-character for these animals."
The
team hope that their discovery will help researchers
understand the brain mechanisms that underlie human mood
disorders, where the perception of reward has gone awry.
Depressed people, for example, commonly fail to find
work rewarding. Sufferers of obsessive-compulsive disorder and
bipolar disorder (also known as manic depression) often work
frantically, sometimes for little reward.
The
study suggests that patients like this may have altered
patterns of D2 receptor expression. Researchers can now test
this hypothesis further in animal and human studies.
References
- Liu Z., et al. PNAS
Online, doi:10.1073/pnas.0403639101
(2004).
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Story from
news@nature.com:
http://news.nature.com//news/2004/040809/040809-10.html | |
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