Cognitive Impression Modeling
From Halopedia, the Halo wiki
Cognitive Impression Modeling, also known as Cognitive Impression Mapping, is a rudimentary form of mind uploading used by human scientists to create "smart" AIs by scanning a human brain, referred to as a donor brain.
The process of Cognitive Impression Modeling is carried out using a device known as the AI Matrix Compiler, the most recent model of which was designed by Dr. Catherine Halsey. The compiler sends electric bursts through the neural pathways of a human brain which are then replicated in a superconducting nano-assemblage, generating a virtual neural network known as the Riemann matrix—effectively the AI's "brain". The human neural map provides only an initial seed for the AI's mind; within moments of its creation, the budding construct will rewrite the neural map into a superior system. This is one of the drawbacks of smart AI creation; initiation time is wasted for the AI by creating the first neural linkages, each of which gradually erodes the AI's limited lifespan.
The ultra-deep personality scan utilized in the Cognitive Impression Modeling process destroys the original brain; as such, it is only legal to use the brains of the recently deceased. These brains are typically acquired from voluntary donors. In the case of the AI Cortana, however, the candidate brain was flash cloned and the host's memories transferred, so that the host, in this case Doctor Catherine Halsey, could remain alive. However, this is extremely inefficient, both from the degeneration of the flash clones and the high rates of schizophrenia and dementia resulting from the memory transfer process. Out of Dr. Halsey's twenty cloned and enhanced brains, only two of them were sufficient and without deformity. Cortana is the only human AI known to have been created this way. Because Dr. Halsey was still alive, Cortana, nearing the end of her lifespan, believed her matrix may be rebuilt using Halsey's neural map, though it was uncertain whether this would actually "cure" her or simply overwrite her personality with a new one.
While clearly a distinct entity from its brain donor, a smart AI will often retain varying degrees of residual memories, thoughts or feelings from the seed brain. These may range from mannerisms, feelings, or even the AI avatar's likeness to the donor (such as in the case of Cortana and Dr. Halsey) or associating certain sensations with those the brain donor may have experienced; Sif, for example, equated the wagons moving on the Tiara's space tethers with the feeling of a hair brush being pulled through her hair, a sensation her brain donor used to enjoy.