This specific form of amnesia is caused by brain damage in the limbic system which is responsible for our memories and emotions.
When the damage occurs it leaves a lacuna, or a gap, in the record of memory within the cortex region of the brain.
Daniel Goleman, in his book Vital Lies, Simple Truths, defines a lacuna as: "...the sort of mental apparatus that diversionary schemas represent.
Theoretically, if you could block that chemical reaction in a human brain while triggering a specific memory, you could make a targeted erasure.
[citation needed] The Caretaker's 2008 album Persistent Repetition of Phrases has the name "Lacunar amnesia" as the title of its opening track.