Ebook: Memory and the Computational Brain: Why Cognitive Science will Transform Neuroscience

Gallistel correctly argues that synapses are too inefficient to act as the "Turing tape" that is necessary for (symbolic) computation, though his reasoning is wrong: the real problem with synapses is that their plasticity interacts, as a result of their extremely close-packing (which is precisely what makes the potentially so useful). This "crosstalk" can undermine sophisticated, quasi-symbolic, synaptic learning. But his proposed "solution", that some unknown new neural storage process analogous to DNA underpins powerful quasi-symbolic brain computations, is pie-in the-sky. Nature is a tinkerer, and it seems much more likely that she has simply patched up the unavoidable defects of synapses using largely ready-made materials. In particular, it's likely, though not proven, that the neocortex is specialised to implement a type of "synaptic proofreading", which allows synapses to act as symbols (see [...]). And the same basic idea, proofreading, also underlies the extraordinarily accurate copying process that underpins Darwinian evolution. So "mind" would be a synaptic version of "life".