Studying the human brain using mice does not work, scientists prove

04/29/2024

Editorial of the Health Diary

Different brains

Neuroscience studies that are based on experiments with mice and rats may be further from serving as indicators of what happens in the human brain than scientists thought.

Contrary to previous assumptions, nerve cells in the human neocortex are wired differently from those in these animals, say Yangfan Peng and colleagues at the University of Berlin (Germany).

Peng discovered that human neurons communicate directionally, in one direction only, while in mice the signals tend to flow circularly, in loops. Direct communication increases the efficiency and ability of the human brain to process information.

“The directed network architecture we see in humans is more powerful and resource-conserving because more independent neurons can handle different tasks simultaneously,” Peng explained. “This means that the local network can store more information. It is not yet clear whether our findings in the outermost layer of the temporal cortex extend to other cortical regions, or to what extent they can explain humans’ unique cognitive abilities.”

On the other hand, in mice and rats neighboring neurons communicate as if they were in dialogue: One neuron signals another and then that other sends a signal back. This means that information often flows in recurring cycles, which is less efficient.

The human neocortex is much thicker and more complex than that of a mouse. However, scientists assumed – in part due to a lack of human tissue samples for study – that the same basic principles of mouse brain connectivity would apply to the human brain. Now it is clear that this is not the case.

Artificial intelligence

In addition to changing textbooks and requiring the redoing of countless experiments, this discovery also promises to help in the development of artificial neural networks, a method used by artificial intelligence.

“Many artificial neural networks already use some form of this targeted connectivity because it offers better results for some tasks,” said Professor Jorg Geiger. “It’s fascinating to see that the human brain also shows similar network principles. These insights into cost-effective information processing in the human neocortex could provide further inspiration for refining AI networks.”