Let me narrow this question down a little, if I may: How are specific memories tagged with emotion? Let's take fear, because that's what I've been looking at recently (and broadly) : The lateral nucleus of the amygdala supposedly pairs stimuli (using run of the mill hebbian interaction) in order to stimulate the central nucleus of the amygala, which in turn activates both the hippocampus and the VTA, among other areas. It seems fairly well understood that the amygdala learns implicitly, so that the conditioned stimulus will elicit the same type of "fearful" later on.
But seeing as how we're talking about the explicit memory system, I think exploring the interactions of the hippocampus post central nucleus will point us in the right direction. Does anyone know if input from the VTA is needed to tag the memory as a fearful one, or is the output from the amygdala sufficient?
If the VTA is in fact a crucial part of fear conditioning, then the memory recalled would serve to activate the tegmental cells. Does anyone know if this is the case? Does suppression of the VTA inhibit the emotional response that comes from the reactivation of the original memory set? Or does anyone know of any research/papers on this subject?