Donald Hebb states it as follows:
"Let us assume that the persistence or repetition of a reverberatory activity (or "trace") tends to induce lasting cellular changes that add to its stability.… When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency, as one of the cells firing B, is increased." Or we can conclude in short: "Neurons that fire together, wire together".
As I understand it, this means that synapses that already exist become stronger between neurons.
- Could new synapses form between neighboring neurons that "fire together", but are not necessarily directly connected through an axon?
- And if so, what is the mechanism to direct the new synapse formation towards that other neighboring neuron that "fires together"?