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by marmaduke
2511 days ago
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> brain simply memorizes an awful lot which must work by a different mechanism besides backprop because backprop cannot do one-shot learning If you look through a neuroscience textbook section on memory systems, it's commonly suggested that the hippocampus does the one shot learning and transfers that over time to the cortex. This is backed up by clinical case studies. > The brain basically outsources the problem of tunneling through large discontinuities, to cultural/individual trial-and-error and episodic memory That seems like a good strategy. It also reminds me of AlphaGo's Monte Carlo search + neural network training setup. Since the search is non differential, you do lots of simulations and apply a differentiable DL model to the results to approximate a possibly discontinuous landscape |
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HC's role in episodic memory and consolidation via dreams seems kinda plausible, though I would not put much weight on it. I think dreams are a way of training a GAN-like discrimination between reality and imagination:
http://gershmanlab.webfactional.com/pubs/GenerativeAdversari...
Repetition of any kind likely does improve the model, even if it's merely simulation/dreaming.
> AlphaGo's Monte Carlo search + neural network
I think, in effect, MCTS amounts to something like bagging/boosting/mixture of experts, as it computes a weighted average of the predictions when exploring different branches. But sure, the search mechanism implements a function which a recurrent neural network could probably not discover as it hides behind substantial discontinuities in fitness landscape (it's not a structure which you can uncover step by step, but you immediately need tree structure, a search recursion etc.). The RNN would likely need to conceptualize the search process (subvocally but) linguistically like humans do, which requires structure for the sequential composition of stable prototypes (symbols) which likely requires a one-shot sequential memory. I think even the human mind does not literally do MCTS (would require an overhead that the brain is just not capable of), but some heuristic approximation thereof. The brain can simulate MCTS by linguistic means, though, even if it's just words of wisdom like "take counsel with your pillow", which literally means explore the hypothesis space some more and let the temporal differences backup better value estimates.