Memory Control (記憶操作 Kioku Sōsa) allows its users to add their existence to other people's memories, delete parts, or even completely rewrite a person's memories of events they took part in. This comes from the major alteration of memory encoding and memory consolidation. Expert manipulation of these two steps can greatly increase a user's chance off affect a person's long term memory storage and recall.
To begin, encoding is a biological event beginning with perception through the senses. The process of laying down a memory begins with attention (regulated by the thalamus and the frontal lobe), in which a memorable event causes neurons to fire more frequently, making the experience more intense and increasing the likelihood that the event is encoded as a memory. The perceived sensations are decoded in the various sensory areas of the cortex, and then combined in the brain’s hippocampus into one single experience. The hippocampus is then responsible for analyzing these inputs and ultimately deciding if they will be committed to long-term memory. The various threads of information are then stored in various different parts of the brain. The hippocampus is one of the few areas of the brain where completely new neurons can grow, and this is where the Memory Control ability begins to take effect. By stimulating the hippocampus with their telekinetic ability, a person is able to cause the growth of new neurons that are able to fire in a particular pattern, in different regions of the brain, to construct a false memory.
Constructing a memory "from the past" is far greater than creating one that takes place in the present or future. This is because in order for a memory to seem fluid within the timeline of a mage's life, a caster would have to be able to pinpoint exactly where a particular memory is stored in order to analyze it's firing pattern to replicate things such as scenery, people present, and radiant sounds. For example putting in a memory of a user's time spent in the snow with their parents, when in fact they grew up on an island as an orphan, would not make sense and be easily seen through as a manipulation.
It is far easier for a mage to construct a false memory during the time of an event due to the fact that they can perceive the current firing of neurons within the hippocampus and alter them to leave out, or include, details that were not there before. This challenge can also be overcome with past memories by having the person think back to the time when an instant happened, allowing them to recall the memory themselves, making it far easier for a caster to locate and alter it.
Emotion in memories are a rather difficult thing to replicate through the use of Memory Control Magic. Emotions tends to increase attention, and the emotional element of an event is processed on an unconscious pathway in the brain leading to the amygdala. Only then are the actual sensations derived from an event processed. A mastery over Memory Control is required to manipulate the emotional connection with a memory, which is why many people who describe an altered memory tend to feel little to no emotion connected to it regardless of the events taking place in the memory.
In order for a mage to create a long-term constructed memory they must alter the consolidation process of memory storage. Consolidation is the processes of stabilizing a memory trace after the initial acquisition and encoding. It is usually thought of as consisting of two specific processes, synaptic consolidation (which occurs within the first few hours after encoding) and system consolidation (where hippocampus-dependent memories become independent of the hippocampus over a period of weeks to years).
Neurologically, the process of consolidation utilizes a phenomenon called long-term potentiation, which allows a synapse to increase in strength as increasing numbers of signals are transmitted between the two neurons. Potentiation is the process by which synchronous firing of neurons make those neurons more inclined to fire together in the future. Long-term potentiation occurs when the same group of neurons fire together so often that they become permanently sensitized to each other.
As the neuron pathway is traversed over and over again an enduring pattern is engraved, and neural messages are more likely to flow along the familiar paths. This process is achieved by the production of new proteins to rebuild the synapses in the new shape, without which the memory remains fragile and easily eroded with time. This means that a mage can either physically, or innately, increase the consolidation process of an altered memory by increasing the potentiation of these newly constructed neurons. This can be done by infusing a large amount of ethernano into the targets body, or through repeated exposure of a visual stimulus to cause the target to retrieve the memory over and over until it becomes a long-term memory. But once the stimulus is gone, a target can soon forget the implanted memory and it will be perceived as a bit of a gap in their own timeline.
- Memory Broadcast (記憶放送, Kioku Hōsō): An additional skill associated with this ability is that the user may, at any given point, relay and subsequently replay their own memories to whomever they desire by firing off the person's synapses in the same order as their own memory; following a similar process as implanting a memory. Implanting a memory can be a very useful ability when going undercover in an operation, but can only be done through maintained eye contact or physical touch. However, the downfall of this technique works in that if the target find out about the truth, the ability will wear off.
- Memory Absorption (メモリーた吸収, Memorīta Kyūshū):The user can absorb memories selectively by copying the arrangement of synaptic configuration from the source, and repeating said arrangement themselves. This allows them to gain some form of advantage, either by enhancing themselves through a skill, gaining the knowledge of a given scenario or attack, or by gaining personal information for various uses. This ability can be used either temporarily or permanently, although to acquire the skill permanently requires a great deal of energy to be flooded into the brain to maintain this neuron configuration. A typical memory absorption will last about two hours before a user's energy will have to be used to maintain the skill or knowledge.
- Memory Erase (メモリ消去, Memori Shōkyo):The user can erase various memories of an intended target by disabling the paths created during consolidation. The user can also erase various limits/limitations or blocks on oneself or others' capabilities. This can be used to erase fears, pain, or for example, removing their target's ability to increase their powers or skills, causing them to decrease or simply remove them.
- Memory Revive (メモリ復活, Memori Fukkatsu): The user can heal others memories which have been altered or even deleted. This works as the reverse path of Memory Erase, and focuses on restoring neural pathways that were once there. This can also work by removing blocks placed to conceal a memory, as it works by making connections to go around said block without the risk of using Erase and accidentally destroying part of the memory's core.
- Memory Scan (メモリスキャン, Memorisukyan):The user is able to read the neural pathways of a target by placing a hand on the target's head and extracts any information needed, even if the target has forgotten it or has had it blocked. The speed at which this is done is dependent on the target's strength, contact time, as well as the energy used to conduction the scan.