In order to understand neural pathways and how they are formed, or how the "forgetting" mechanism works, etc., it is essential for you to gain access to a good Psychology 101 text and read the chapters associated with MEMORY. How memory works (or doesn't work) is all included in this topic. Many, many neural functions are hard at work simultaneously, which involve short & long-term memory alike. For example: Memory can be changed, or affected, simply by using Lexicons. This technique can assist with "unlearning" a non-desirable, or irrational memory, or persistent negative thought, while allowing new, better thoughts to take hold. I am confident all of the answers you seek will be gained via any basic Psych 101 text. All Best!