


So, when we learn new things, we store memories. And the most important process in storing memories is that the synapses as what i pictured above is playing a role to cement the memory. Those synapses have to be strengthened so that the memory is in place and stays there.
To strenghten synapses, we needs to make new proteins since these proteins builds the synapses and make it stronger.
It was just like exercise, new proteins are needed to build up muscle mass, and so do synapses.
The production of new proteins can only occur when the RNA that will make the required proteins is turned on. Until then, the RNA is "locked up" by a silencing molecule, which is a micro RNA.
When we are starting to hearing or watching something interesting, or we could say as remembering, synapses got activated, and one of the proteins wrapped around that silencing complex gets degraded. Then the RNA is suddenly free to synthesize a new protein.
So when we forget something, the synapses are gone or the connection between one neuron to another one are lost.