A mnemonic neural recall stimulator, also known as a graybox, is a device implanted in the brain to assist and prioritize memory. Originally developed to slow the progression of Alzheimer's disease, grayboxes function by helping the amygdalae "chunk" incoming stimuli into recognizable pieces for memory consolidation. Each memory is assigned a shape or sensation from other memories, tying the concepts together into a block that is more easily recalled.
When Synthetic Insights first released them onto the market in 2140, grayboxes were hailed as a way humans could level the playing field between themselves and the salarians, whose natural eidetic memories gave them an advantage. However, because the implant procedure of a graybox requires the brain to irreversibly shift its workload over to the machine, software bugs or attempted removal of the graybox for maintainance [sic] purposes could lead to incapacitating brain damage. For this reason, grayboxes soon became used only by those with a dire need for photographic memories, such as researchers and spies.
In 2175, sale and implantation of grayboxes were outlawed by the Systems Alliance following an incident with Abraham Rumoi, an employee of the Alliance Intelligence Agency. Rumoi was believed to be a professional con man and thief named Keiji Okuda, who accessed and sold classified data. However, prosecuting attorneys were unable to use his assisted memories as evidence due to the Alliance court system's prohibitions against self-incrimination (based on the Fifth Amendment of the old U.S. Constitution). Rumoi soon disappeared off the map following his trial, further heightening suspicions that he was Okuda and living off of ill-gotten gains.
When found outside a human head, grayboxes are usually accessed with a specialized reader. A separate decryption key is almost always required, as users with data sensitive enough to require a graybox invariably install their own encryption.