Hi
The answer is called a mutation
1983-1984 was when it was discovered
Caused by sexual contact are more difficult to treat..
You didn't really provide any possible answers here. However, it's very easy to say that the responsible actors for impulse transmission across the synapses from one nervous cell to another nervous cell is what we call neurotransmitters. These are special molecules that can have different effects when binding onto the required receptor sites.
