Why is the dream world generated by the brain so large and real during dreaming, but the brain memory is so low during waking?

When you are awake, employees in all areas of the brain are working hard, processing all kinds of information, and no one is touching the fish, so reality is very "real".

The state of "reality" is actually defined by the brain itself.
You are still working hard while you are sleeping, but because the employees in certain key positions are asleep, there is a lot missing from the processing assembly line of various information, so the dream is very "absurd".

This one, which often loves to rest and not work with everyone, is called the dorsolateral prefrontal lobe and is responsible for logic and reasoning.

There is a small problem here, though:

When awake, all information comes from external signals received by the sensory system (such as visual and auditory), but when dreaming, the sensory system is in a dormant state, so where does all the information processed come from?

The answer is: from the hippocampus.

During wakefulness, all kinds of information are stored in the hippocampus, and during sleep, this information is released and uploaded to the cerebral cortex, where it becomes long-term memory.

During the release of this information, the thalamus (a sensory transmission relay station) screens it and distinguishes what is true and what is false.

But since the prefrontal lobe is not online, the thalamus can't figure it out, so it simply gives both hands to the occipital lobe (the visual cortical center).

The occipital lobe is also very dizzy in the face of indistinguishable information, and has to call other employees who have not yet slept to help, we all brainstorm together.

There were two main employees who came to support us: the pike gyrus (visual) and Wernicke (auditory).

The shuttle back is responsible for brainstorming images, Wernick is responsible for brainstorming voiceover.

But due to the lack of material (sensory system are sleeping), the two brothers are what they have on hand to make up what, just like a child scribbling, that is called a mess.

So you start to have strange dreams.
This is when two employees show up uninvited: the amygdala (emotions) and the anterior cingulate gyrus (cognition).

The amygdala is responsible for fear, and the anterior cingulate gyrus is responsible for anxiety and aggression.

So you start having nightmares.
This forces the precentral gyrus (motor center) to come online as well.

The precentral gyrus is responsible for escape and avoidance.

But due to the lack of external perception (the sensory system is still asleep), the precentral gyrus is left to run and jump around, and nobody cares.

So you start flying, parkour and jumping in your dreams.
This can be the shuttle back and Wernicke busy, the two would have been a lack of material, random brainstorming, the central former back also kept tossing, the two were forced, simply all the scenes in the memory, a brain pulled in to make up the numbers.

So you will dream of your home, then dream of school, then dream of tall buildings, then dream of Mars.
The shuttle back is a little more bitter, because the picture is more informative.

If you dream of a scene is fine, can be uniform, the character is a problem, must be a thousand people, shuttle back to have to grab a random person on the hard.

So you dream of many strange faces, they are just passers-by in life.
At this point, you see a strange girl is very good, want to go up to ask for a cell phone number, but found how can not remember the number.

Because the dorsolateral prefrontal lobe, which is responsible for logic and reasoning, is still asleep.

So you don't care, hold the girl and want to that what.
Once excited, the brain starts to secrete dopamine and serotonin rapidly, and the dorsolateral prefrontal lobe is activated online at the critical moment.

Then you wake up.

This is the whole process of the "grand and real" dream.