The Brain's Roladex

This was me two days ago. My friend and I were having a conversation, when suddenly... a long pause. I hate when that happens! You know that moment when it's on the tip of your tongue, but just can't spit it out? Yeah.
So a friend explained to me that when you know something, but just can not think of it, your brain does not give up the search. She explained it as "the sensors in your brain are thumbing through it's roladex/index." So, this was my illustration to match the explanation.