The nerve cells in the hippocampus have to be archived both just experienced and dig out memories again. But how does the brain only recognize on the basis of the electrical signal whether it is fresh goods for the thought store or long -known knowledge that is brought out again? The neurologist Hye bin Yoo watched with two colleagues from the University of Texas Southwestern Medical Center for the first time how the human thinking organ makes this distinction.
Test subjects were 27 epilepsy patients with implanted electrodes to record brain activity. The experiment was simple: First, the subjects were asked to learn a list of things. After a brief distraction, they had to retrieve the words. The nerve signals for memorizing and remembering one and the same term were identical, only the timing differed. Experts refer to this as a »phase offset«.
Might be useful in understanding schizophrenia
Neurons send their signals at a certain frequency, the rate of fire. You can imagine it like the hand of a clock, which rotates faster at a higher frequency, for example. If you memorize a word fresh or remember it, it doesn't change the speed. However, Yoo's team observed that – figuratively speaking – the position of the pointer at which the nerve cells send their signals changes; so they fire at the same rhythm, but at a different time.
"This is one of the clearest evidence of how the human brain works when it comes to remembering something or forming new memories," says Bradley Lega, who was also involved in the study. In the future, the results may help with understanding schizophrenia. Because those affected often cannot distinguish their own memories from delusions, which could also be explained with a disturbed phase offset.
