Figure 1.

Regrowth of a tree after a lightning strike as a metaphor for recovery of function stroke. The flourishing tree represents the intact nervous system before lesion (A). A lightning strike on the tree results in broken and withered branches (B and C). However, because the trunk and root remain intact, continuous watering and fertilizing the tree help the withered branches to regrow (D and E). In the nervous system, strength in the contralesional limbs is reduced dramatically in the first few months after lesion (C). However, by unitizing the interlimb neural networks conserved from our quadrupedal ancestors (represented by the monkey watering the tree), neural plasticity can be induced across the body even years after lesion (D and E).