ScienceDaily has an item (here) on a U of Pennsylvania press release about decoded neural patterns of memory recall. The research was done by M. Kahana, J. Manning and others. They took advantage of the opportunity presented by epileptic patients with implanted electrodes allowing experimentation on their brains during the wait for surgery. Recordings were made from the electrodes while the patients studied 15 words and than repeated them in any order.

The researchers examined the brain recordings as the participants studied each word to home in on signals in the participant’ brains that reflected the meanings of the words. About a second before the participants recalled each word, these same “meaning signals” that were identified during the study phase were spontaneously reactivated in the participants’ brains.

Because the participants were not seeing, hearing or speaking any words at the times these patterns were reactivated, the researchers could be sure they were observing the neural signatures of the participants’ self-generated, internal thoughts.

The subject’s patterns were individual. But there was a similarity between the how much patterns for different words overlapped and how close words were in order of their recall. The research implies that there is a neural signature in organizing of learned information by meaning.

“In addition to looking at memories organized by time, as in our previous study, or by meaning, as in our current study, one could use our technique to identify neural signatures of how individuals organize learned information according to appearance, size, texture, sound, taste, location or any other measurable property,” Manning said.