How precise is the connectivity in the cerebral cortex?
It is common in neuroscience literature to read statements about the precision of the connectivity in the brain. But is the connectivity, especially in the cerebral cortex, really precise? First, I will define the word ‘connectivity’. By ‘connectivity of a group of neurons’ I mean a listing of all the existing synapses between any pair of them. With this definition the strength of the synapse is immaterial to the connectivity, so potentiation/depotentiation of synapses does not affect connectivity. Secondly, I will concentrate on the cerebral cortex, because it demonstrates the point I make most clearly. How can we tell, in principle, if the connectivity is precise? The ‘obvious’ way is to compare it to the plan of the connectivity. The problem is that we don’t know what the plan is, and in fact we don’t even know that there is a plan. Instead, we can compare between different individual brains. If there is a plan to which the connectivity in the cortex conforms, then the connectivity
