So we know that during the window of neuroplasticity, the injured brain is poised to make new connections between neurons. Profound molecular changes are happening in surviving neurons and supporting cells to sculpt neural circuits. What the person with brain injury does-that is, his or her behaviour- determines what connections will be made. It is important to realize that this sensitive period is limited by both time and capacity (the bowl of popcorn). The first 4 weeks or so seem to be critical. Theresa Jones and colleagues at University of Texas at Austin have shown that rodents after stroke have a heightened ability to learn complex motor skills with the unaffected limb (the good one). They are better at learning than animals that have NOT had a stroke! This suggests that the brain after injury is ripe to acquire new movement but not in the affected limb! Synaptic competition is at play early after injury. This means that groups of synapses are competing to help the brain recover. Without physical therapy after brain injury, it seems that synapses that improve control of the unaffected (good) arm usually win out. This is probably a survival mechanism to allow the animal the most opportunity to survive (forage for food, protect itself etc). However, possibly like our right-handed gentleman who became extraordinarily skilled at using his left hand for just about everything (read After brain injury, neuroplasticity is like a bowl of popcorn to refresh), Jones and colleagues have also found that this enhanced function of the unaffected limb comes at a price-loss of neuroplasticity in the injured brain hemisphere and impaired recovery of the affected limb. This means that without guidance to use the affected limbs, the neuroplastic capability will be used to improve control of the unaffected limbs AT THE EXPENSE of recovery of the weak limbs. It is important then, that the person after brain injury is encouraged to use the affected limbs within the first few weeks. It is probably not realistic to expect them to brush their hair with the weak arm. They should make sure the arm is placed on the table rather than in the lap; that they hold a bottle or toothpaste tube while opening it with the better hand; physically place the arm where it should be for a task. When standing up from a chair the person with brain injury should be encouraged to place equal weight on each leg-do not shift to the stronger side. Obviously safety is the number one priority and a steadying hand should be available when needed. I will talk more about practical tips to promote recovery in later postsā€¦