Interesting perspective. I imagine trails as graphs and stepping through a graph is like looking at the components of a time-domain representation of a signal so in my mind associative trails are a time-domain representation of thinking. But you might be onto something. I've been thinking about how to incorporate search into something I'm working on and search can be considered a frequency representation because finding and ranking documents is about finding the frequency components relevant to the query. If associative trails can incorporate search then that might be a good enough frequency-domain representation.

In the context of knowledge engineering I think "frequency" representation has to be dynamic and search is a very simple form of dynamism. But I might be thinking about this the wrong way and your view might be more correct, i.e. static content = frequency domain, dynamic content = time domain.