The "decition" is made by the spinal cord. It's not surprising if you imagine that the brain is an oversized part of the spinal cord.
See also https://en.wikipedia.org/wiki/Ganglion
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If I can make a bad approximation:
* Making circuits with normal cells is like making circuits with resistors and capacitors.
* Making circuits with neurons is like adding transistors to the mix.
(Please don't take this analogy too seriously, probably biologist and electricians are writing angry replies now.)
Electrically Excitable Cells
https://neurotext.library.stonybrook.edu/C4/C4_1/C4_1.html
The "decition" is made by the spinal cord. It's not surprising if you imagine that the brain is an oversized part of the spinal cord.
See also https://en.wikipedia.org/wiki/Ganglion