Memory block (brain)
A memory block was a means of preventing a memory to surface in an individual. 

The Trill Symbiosis Commission initiated such a block within the Dax symbiont, to prevent the memory of Joran Dax from being revealed to Curzon and later Jadzia Dax. After eighty years, the block began to wear off, allowing Joran to surface. ()

See also
Memory wipe
Repressed memory

Medical procedures