Connections between neurons, the synapses, are encoded. So much so that they are given individual names. This is a fun one to read about to get an idea: https:

Connections between neurons, the synapses, are encoded. So much so that they are given individual names. This is a fun one to read about to get an idea: https://en.wikipedia.org/wiki/Calyx_of_Held https://en.wikipedia.org/wiki/Calyx_of_Held