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It was never an accurate model (in the sense that it never modelled, eg., plasticity and many more things). It was however an attempt to actually model activati
by mjburgess 5y ago
It was never an accurate model (in the sense that it never modelled, eg., plasticity and many more things). It was however an attempt to actually model activation patterns as boolean circuits.
However as soon as you make it a supervised optimisation alg it fails even to be a model. (The NN algorithm is just k-nearest-neighbours + recursive PCA.)
Activation patterns in the brain aren't "trained" by backprop, and they dont form a piece-wise linear (ie., ReLU) regression function.
It's better to say that the optimisation algorithm called "Neural Networks" was inspired by the "Neural Network" model of the brain which was a partially highly simplified model of one aspect of neurone behaviour.
The algorithm used today has nothing homologous with anything in the brain -- and its somewhat incoherent to suppose it does. A piece-wise linear regression model of the boston house price dataset is a meaningless stand-in for anything neurological. Its aburdist marketing to say otherwise.
- dnautics 5y ago> its somewhat incoherent to suppose it does Agreed, but the principle of convergent evolution is a thing. It's possible that and we cannot rule out that we are accidentally stumbling our way into homologous models of biological compute (I personally doubt it).
- mjburgess 5y agoWell in the sense that the activation map over the brain is a function of space-time, ie., A(x, t) -- it is possible that the activations in a NN might instantiate this function... but that's literally probability 0. As the set of such functions, R^2 -> R are uncountable infinite.
- dnautics 5y agoIf you imagine the space of all possibilities as R^n -> R and the solution to be only one mapping function and not "some subspace of the possibility space", possibly around some ball of results, I got some news for you.