"Researchers have begun to show that it is possible to use brain recordings to reconstruct aspects of an image or movie clip someone is viewing, a sound someone is hearing or even the text someone is reading. A new study by University of Pennsylvania and Thomas Jefferson University scientists brings this work one step closer to actual mind reading by using brain recordings to infer the way people organize associations between words in their memories. (...) 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. (...) Since the participants were instructed to say the words in the order they came to mind, the specific sequence of recalls a participant makes provides insights into how the words were organized in that participant’s memory. (...) “Each person’s brain patterns form a sort of ‘neural fingerprint’ that can be used to read out the ways they organize their memories through associations between words,” Manning said.
The techniques the researchers developed in this study could also be adapted to analyze many different ways of mentally organizing studied information.
“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. (...) Our data show a direct correspondence between patterns of brain activity and the meanings of individual words and show how this neural representation of meaning predicts the way in which one item cues another during spontaneous recall.
“Given the critical role of language in human thought and communication, identifying a neural representation that reflects the meanings of words as they are spontaneously recalled brings us one step closer to the elusive goal of mapping thoughts in the human brain.”