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24 April 2014 11:45 am ,
Vol. 344 ,
The National Institutes of Health is revising its "two strikes" rule, which allowed researchers only one chance to...
By stabilizing the components of retromers, molecular complexes that act like recycling bins in cells, a recently...
Fossil fuels power modern society by generating heat, but much of that heat is wasted. Semiconductor devices called...
Researchers are gaining insights into what made Supertyphoon Haiyan so powerful and devastating through post-storm...
Millions around the world got a first-hand look at what it was like to be in Tacloban while it was pummeled by...
Major climate data sets have underestimated the rate of global warming in the last 15 years owing largely to poor data...
The tsetse fly is best known as the vector for the trypanosome parasites that cause sleeping sickness and a disease in...
- 24 April 2014 11:45 am , Vol. 344 , #6182
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10 November 1997 8:00 pm
There's not much to love about a lamprey, an eellike parasite that clamps onto other fish and sucks their blood until they die. But physiologists have latched onto the lamprey's primitive nervous system as a way to understand how the brain directs movement. Now, for the first time, researchers have observed the lamprey's brainstem converting a sensory input--a bump on the snout--into a command to swim away. This kind of wiring, described in the current issue of Science, may be present in higher vertebrates, including humans--and if so, it might provide insights for scientists studying how to treat paralysis from spinal cord injuries.
Scientists have taken advantage of the lamprey's simplicity--its neurons number in the thousands, while humans have billions--to produce the first complete blueprint of a vertebrate motor system. In 1987, they discovered that the repetitive motions of swimming are choreographed by a group of neurons in the lamprey's spinal cord called the central pattern generator (CPG). The brain, instead of controlling each movement individually, merely turns on the CPG's swimming program.
To find out how the brain knows when to issue the command, physiologist Réjean Dubuc of the University of Quebec in Montreal and colleagues at the University of Montreal applied pressure to the skin of a tied-down lamprey's head. Using tiny electrodes, they monitored the response of brain cells responsible for movement. When the pressure was mild, the electrodes registered a small increase in voltage. But at a certain threshold--like a tickle turning to a sneeze--the electrical activity suddenly spiked, and simultaneously the lamprey's tail began to swish back and forth, as if the creature were swimming, continuing for about 20 seconds.
The new findings prove that a group of cells in the brain can turn a short-lived sensation into complex, long-lasting muscle movements, says physiologist Simon Alford of Northwestern University. The work also bodes well for helping people with injured spinal cords to walk again, he says: If just one connection from the brain has to be repaired, "then hope becomes much stronger that spinal cord regeneration could be successful."