Part 14: Infiltration14
The Blood-brain barrier or BBB is like a screen that exists along capilaries in the brain and separates molecules and small organisms, preventing some from entering neuronal proximity while letting others in. Most bacteria and medicines are too large to pass through the barrier, but neurotransmitters, the brain's own chemicals of cognition, and certain drugs can. One technique is to send in a medicine in smaller, inert pieces that can pass through the BBB and reform as effective medicine on the other side. Infections of the brain are rare because of this mechanism, and anything that does get in is much more dangerous because of it.