"Um, Hana."

　What is it, Ursula?

"Excuse me, but from what you've said so far, there is still a discrepancy in the item on "Brain's Empty Burial"."

　Is there a discrepancy?

　"Yes," Ursula said, gently placing his hands on the desk. Yes, stopping his hand. ―― looks like a playing a theremin gesture.

　I could see that Ursula's consciousness had turned to the mirror on the wall for a moment. I could sense that he had asked him colleagues to take over the work so that they could continue recording inside instead while Ursula was stopped.

　I know that Ursula's brethren on the other side of the glass, pretending to be a mirror, undertook it with a gesture that only they could understand.

"Hana, Liz has some kind of lesion in her brain, which has made it difficult for her to preserve her ego, right?"

　Yes. Right.

　The roles of the "Old Humans" brain are roughly divided according to the part, and the quality of cooperation between the parts changes depending on the level of learning as a result of receiving external stimuli, and this is expressed as a disparity between individuals.

　The learning of Old Humans is first received as information in the limbic system area called the hippocampus. This received information is transferred to the cerebral cortex and becomes a memory and is consolidated. The limbic system is located in the central part of the brain, and the cerebral cortex is the outer part that envelops it.

　If we compare information to luggage, the hippocampus is an organ that corresponds to the reception window or reception of the package. And the cerebral cortex is assigned to the warehouse that stores this accepted package.

"So, it doesn't stick in the hippocampus itself as a memory?"

　You're right. The information that the hippocampus receives from the outside is passed to the cerebral cortex and then gradually disappears from the hippocampus. It's only natural that if you hand over a package to the warehouse, it will disappear from the hand where you received it.

　However, it is difficult for the cerebral cortex to completely establish it as a memory just once it has received information.

"Uh-huh...... In other words, in order for "Old Humans" to memorize information, they had to learn repeatedly?"

　Right. The hippocampus receives the same information over and over again, and it is repeatedly passed to the cerebral cortex, which becomes a memory and becomes deeply entrenched in the brain.

　But it's not linearly controlled. In the limbic system, which has this hippocampus, there is a thing called the amygdala.

"Is it the amygdala?"

　Yes. The amygdala is the part that controls emotions and is in contact with the hippocampus. When the hippocampus receives information from the outside, the amygdala sorts the information it gets into good and bad, that is, pleasure and displeasure, joy, anger and sorrow.

"I mean, when "Old Humans" understand something, they interpret it into something emotional. I mean, you're labeling, right?"

　Right. This sense of pleasure and discomfort was originally a very effective mechanism for the survival and maintenance of their material and physical bodies, but this is where the so-called causes of discrimination, prejudice, and love.

"Uh, uh, love?"

　Yes. Love.

"Ah—I see, so bad emotions are a necessary classification for a quick escape from a life-sustaining hazard, such as being preyed upon, in other words, to classify what is good or bad for an individual's biological proposition, isn't it?"

　Right.

"If this is also true of love, it is about reproduction, which means that one's own species is definitely passed on to the next generation, and in order to succeed in this, it is necessary to acquire the opposite sex of the same species as oneself. This means that it needs to be immediately recognized that the object resembles itself and that it is healthy."

　Absolutely. At the same time, this means that no matter how similar they look, they cannot be treated as different species that do not match their genomic structure, so they are forced to react in a way that avoids them.

"Oh...... I see—so it's an instinctive survival strategy that is set up to make the typological subspecies feel threatened and uncomfortable?"

Yes. You're right. Attachment and sexual urges to other species that are unable to reproduce, or to unhealthy and degraded individuals, even if they look similar to themselves, are inhibiting reproduction. So, in order to avoid this, a mechanism was built in to detect discomfort -- this was called the "uncanny valley" by the Old Humans.

"Uncanny—Oh, really, it's determined by good and bad emotions."

　Yes. And Liz's suffering from Alzheimer's Disease is a disease that originated from this hippocampal atrophy. Therefore, it becomes difficult to purchase new information first. In addition, the amygdala, which distributes this with emotions, is in contact with this hippocampus, so it is quickly affected by deterioration.

"In other words, it becomes difficult to receive new information in the first place, so it becomes difficult to communicate immediately, and because they are not receiving information, they cannot remember anything new.　Naturally, they won't be able to sort out their emotions — that is, you won't be able to organize them as memories."

　Right. The more the disease progresses to the amygdala, the more the emotion sorting mechanism does not work, so it becomes difficult to sense the joy, anger, sorrow, good and bad contained in the facial expressions and gestures of others.

　In other words, damage to the amygdala means the disappearance of emotion, the "key to understanding and judging information," from all of oneself.