Describe precisely the way that a signal will cross the synaptic gap?

Neurotransmitters,more commonly called,Serotonin,dopamine,Norephenephrin, spellings might not be correct,the speaking of them is.

Further looking online will state more information the I could, these are just a few I know of.

SSRI(selective serotonin re uptake inhibitor)and typical anti depressants(Prozac,Zoloft,Celexa... etc)their use is to stop the serotonin from being reintroduced into the brains chemicals,allowing more dopamine(pleasure chemical)to continue to do it's job.

I can't know much more than that,and it might be a little off anyway,the basics can be found by doing a Google search of the 3 major ones though!

Hope this helps,

Ken