Postnatal conversion of cross phrenic activity from an active to latent state

When the spinal cord is injured in the neck, it can paralyze the diaphragm, making it hard to breathe. Sometimes, the body can use another pathway to help the diaphragm work again. This study looks at how this other pathway, called the crossed phrenic pathway, changes as rats grow from babies to adults. In newborn rats, this pathway is active, but as they get older, it becomes less active and eventually stops working. This study found that this pathway is active in newborn rats but becomes inactive by the time they are about five weeks old. Understanding how this pathway changes could help scientists find new ways to help people with spinal cord injuries breathe more easily.

• 1
  Crossed phrenic activity is spontaneously expressed in all three parts of the ipsilateral hemidiaphragm of P2 rats following C2 hemisection injury.
• 2
  The time window for the conversion of spontaneous crossed phrenic activity from three areas of the hemidiaphragm to one area (ventral) occurred between P3 and P5.
• 3
  By the end of the fifth postnatal week (P35), the expression of the crossed respiratory activity was completely suppressed.