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The Body Electric
ing at the site of damage, it extends in all directions until the entire
cortex becomes electrically positive and all its neurons shut down. Leao
studied it only in response to small injuries, when it persists for a few
hours. We don't know whether it occurs in the salamander or how long
it lasts after major damage to the mammalian brain. Concerted study of
Leao's depression combined with experiments in electrically stimulating
the ependymal cells could open the way to self-repair of the human
AMPHIBIANS CAN REGENERATE LARGE PARTS OF THE BRAIN
Recovery from stroke and head wounds taught us long ago that the
brain has a great deal of plasticity; that is, it can reorganize so that
undamaged regions take over tasks formerly done by the lost cells. Sup-
plementation of this ability with even a small amount of regeneration
might make recovery nearly complete for many brain-damaged people.
For the first time in history, neurologists can hope to progress from
describing the brain and cord to mending them. As Geoffrey Raisman of
London's Laboratory of Neurobiology recently reminded his colleagues:
". . . no immutable natural laws have been discovered that forever rule
out repair of the nervous system."