This concept apparently goes back at least as far as Robert Ettinger, the originator of cryonics. From his seminal book introducing cryonics,
We normally think of information about the body as being preserved in the body—but this is not the only possibility. It is conceivable that ordinary written records, photographs, tapes, etc. may give future technicians enough clues to fill in missing or damaged areas in the brain of the frozen.
The time will certainly come when the brain’s method of coding memories is thoroughly understood, and messages can be “read” directly from nervous tissue, and also “read” into it. It is not likely that the relation will be a simple one, nor will it necessarily even be exactly the same for every brain; nevertheless, by knowing that the frozen had a certain item of information, it may be possible to infer helpful conclusions about the character of certain regions in his brain and its cells and molecules.
Similarly, a mass of detailed information about what he did may allow advanced physiological psychologists to deduce important conclusions about what he was, once more providing opportunity to fill in gaps in brain structure.
It follows that we should all make reasonable efforts to obtain and preserve a substantial body of data concerning what we have seen, heard, felt, thought, said, written, and done in the course of our lives. These should probably include a battery of psychological tests. Encephalograms might also be useful.
This concept apparently goes back at least as far as Robert Ettinger, the originator of cryonics. From his seminal book introducing cryonics,