Theta wave occurs in the hippocampus when inputting information. This theta wave works to compress time to about ten times.

Fig: Time compression by the hippocampus

Horizontal arrow: Time series

Wave: theta wave (4~12Hz)

入力の時間 = input timing

再生の時間 = playback timing

10倍に圧縮 = compressed 10 times

A, B, C, D in the figure are different hippocampal cells. Suppose they are stimulated in the order A, B, C, D. The stimulated cells ignite first in sync with the theta wave and then repeat the firing at intervals shorter than 10% from the theta wave. The hippocampus repeats the information many times in itself. Moreover, this playback is played in 1/10 of the input time. It is similar that watching the high-speed playback which 10 times faster than the recording speed.

This experiment was done with rats, using cells related to the memory of position in the hippocampus. Concrete information entered from the eyes of the rat of what they saw the scenery. But rats cannot observe their own position directly. That is, the position is abstract information. The process of creating abstract information from concrete information works in the hippocampus.

We do not know how the work of hippocampus, which creates positional information from the scenery information, is related to make long-term memory. However, I think that there must be some relation between them. The memory technique "Method of loci" which uses the position, the analogy of the map such as "Civil Code Map" introduced in (1.3.3.5) Civil Code Map, the hippocampus is used for both understanding position and making long-term memory, are side evidence.

Regarding compression of time, I think that it is related to the idea of "rhetorical afterimage" explained in Chapter 4, saying "we can not understand if I read too slowly."