The physical realization is the number of postsynaptic receptors. In terms of fast excitatory transmission it is the quantity of AMPA receptors. You can potenti

The physical realization is the number of postsynaptic receptors. In terms of fast excitatory transmission it is the quantity of AMPA receptors. You can potentiate or depress synapses by controlling the amount of these receptors. This has been demonstrated in vivo, and in cell culture. We are at the point where we can manipulate the strength of individual synapses. Here is a nice review article: https://royalsocietypublishing.org/doi/10.1098/rstb.2013.0136?url_ver=Z39.88-2003 https://royalsocietypublishing.org/doi/10.1098/rstb.2013.013...