Fickle Neurons

A new paper, Beyond dimension reduction: Stable electric fields emerge from and allow representational drift, suggests that electrical fields generated by the brain stabilize mental representations. Here is the abstract:

It is known that the exact neurons maintaining a given memory (the neural ensemble) change from trial to trial. This raises the question of how the brain achieves stability in the face of this representational drift.  Here, we demonstrate that this stability emerges at the level of the electric fields that arise from neural activity.  We show that electric fields carry information about working memory content. The electric fields, in turn, can act as “guard rails” that funnel higher dimensional variable neural activity along stable lower dimensional routes. We obtained the latent space associated with each memory. We then confirmed the stability of the electric field by mapping the latent space to different cortical patches (that comprise a neural ensemble) and reconstructing information flow between patches.  Stable electric fields can allow latent states to be transferred between brain areas, in accord with modern engram theory.

A press release from MIT has a more simplified description of the research.

I’ve noted several studies in recent years that demonstrate the lack of correspondence between subjects and over time in the same subject of neuron firings while the same task is being performed. To quote from the release:

Indeed, whenever neuroscientists have looked at how brains represent information in working memory, they’ve found that from one trial to the next, even when repeating the same task, the participation and activity of individual cells varies (a phenomenon called “representational drift”). In a new study in NeuroImage, scientists at The Picower Institute for Learning and Memory at MIT and the University of London found that regardless of which specific neurons were involved, the overall electric field that was generated, provided a stable and consistent signal of the information the animals were tasked to remember.

This observation aligns well with McFadden’s cemi theory and his prediction number 8. Different neural firings can produce the same or similar waveforms. A given firing will produce a defined waveform but the waveform itself cannot be reverse engineered to a definitive firing. The “representational drift” actually may be adaptive in that it is the brain’s way of trying to find a best fit for its representations through a conscious feedback process.

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5 Responses to Fickle Neurons

  1. Interesting paper James. I imagine Eric will be thrilled, although the focus is on the information processing that happens in the field, so not sure.

    The paper seems to get very technical, so I read the press release. I’ll have to leave it to the neuroscientists and related specialists to assess the overall methodology. The authors are making some pretty strong claims. It will be interesting to see if these results hold up.

    Liked by 1 person

  2. Cody White says:

    To a layman like me (and I’m sure other readers of this blog) this all makes intuitive sense and nicely matches the thought experiments and visualizations I run in my mind. Not that that counts for anything – but it is comforting to believe that the mechanics of mental representation would not be completely estranged from our ability to mentally represent them. Theories that don’t rely on some form of physical substrate to embody/contain information just make no sense to me. I can’t compute them, even though I am sometimes assured they are more reasonable.

    Liked by 1 person

    • James Cross says:

      Your intuitive sense matches my own and explains why I was gradually led to the idea that EM field theories are the best explanation available at the moment for consciousness.

      Without something physical (that is “from physics”) we are left with the supernatural. However, if consciousness is something physical, it seems clearly different from matter and most physical phenomena except for things field/wave based. It may turn out to something other than an EM field, perhaps some other previously unknown type of field, but hypothesizing a new field seems more of a stretch than seeing how far we go with a field that we can actually detect in the brain and increasingly find evidence of its effects.

      Like

  3. Thanks for thinking of me guys! I’ve been a bit behind on my blogging lately. I’m trying to finish up critiquing Schwitzgebel’s coming “Weirdness of the world” book so that hopefully he’ll tilt it a bit more towards my perspective (or where things get too conflicting, perhaps at least in the future).

    Yes this does seem like at least somewhat of a move towards empirical validation for McFadden’s cemi. And Mike’s instincts are right that there’s something here which I don’t like. Apparently it either didn’t occur to these scientists that stable EM fields themselves might exist as the phenomenal experience of memory, and that this might be the case for all phenomenal experience. Or maybe they were aware of McFadden’s theory but decided to see if they could fit their evidence into the standard neuroscience paradigm anyway? It would be nice if they’d now go back and at least reinterpret their data as an empirical test of his theory, or better still design a new experiment given the particulars of his proposal. Sometimes unworkable paradigms become so mainstream that people continue trying to validate them rather than think differently.

    Liked by 2 people

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