Using a new molecular genetic technique, scientists have
turned procrastinating primates into workaholics by
temporarily suppressing a gene in a brain circuit involved
in reward learning. Without the gene, the monkeys lost
their sense of balance between reward and the work required
to get it, say researchers at the NIH’s National Institute
of Mental Health (NIMH).
“The gene makes a receptor for a key brain messenger
chemical, dopamine,” explained Barry Richmond, M.D., NIMH
Laboratory of Neuropsychology. “The gene knockdown
triggered a remarkable transformation in the simian work
ethic. Like many of us, monkeys normally slack off
initially in working toward a distant goal. They work more
efficiently – make fewer errors – as they get closer to
being rewarded. But without the dopamine receptor, they
consistently stayed on-task and made few errors, because
they could no longer learn to use visual cues to predict
how their work was going to get them a reward.”
“This new technique permits researchers to, in effect,
measure the effects of a long-term, yet reversible, lesion
of a single molecular mechanism,” said Richmond. “This
could lead to important discoveries that impact public
health. In this case, it’s worth noting that the ability to
associate work with reward is disturbed in mental
disorders, including schizophrenia, mood disorders and
obsessive-compulsive disorder, so our finding of the
pivotal role played by this gene and circuit may be of
clinical interest,” suggested Richmond.
“For example, people who are depressed often feel nothing
is worth the work. People with OCD work incessantly; even
when they get rewarded they feel they must repeat the task.
In mania, people will work feverishly for rewards that
aren’t worth the trouble to most of us.”