Some of what the body does in response to injury, especially in the nerves and brain, is in fact counterproductive in the long term: "Stroke is the leading cause of adult disability, due to the brain's limited capacity for recovery. ... Researchers interested in how the brain repairs itself already know that when the brain suffers a stroke, it becomes excitable, firing off an excessive amount of brain cells, which die off. The UCLA researchers found that a rise in a chemical system known as 'tonic inhibition' immediately after a stroke causes a reduction in this level of excitability. But while this 'damping down' initially helps limit the spread of stroke damage, the increased tonic inhibition level and reduced brain excitability persists for weeks, eventually becoming detrimental to the brain's recovery. ... It was surprising to find that the level of tonic inhibition was increased for so long after stroke and that there was an inflection point where the increased level eventually hindered the brain from recovering. It was also surprising that we could easily manipulate tonic inhibition in the brain after stroke to restore it back to a normal, 'non-stroke' level and, in doing this, enhance behavioral recovery. ... They found that by applying specific blockers of this inhibitory brain chemical, they could then 'turn off the switch.' The resulting enhanced brain excitability immediately improved behavioral recovery after stroke."