This article is from the public number: Neural Reality (ID: Neurality) , author: Thiago Arzua, Medical College of Wisconsin and now a PhD in neuroscience, translation: wolf Gu, proofreading: Zhang Meng

The “mini-brain” is used to simulate and study genetic diseases, major mental diseases, neurodegenerative diseases such as Alzheimer’s disease, and even human evolution.

We are in the tide of organoids. These miniature organ models are rapidly making exciting new progress, and the brain-like organ is one of the most interesting. Brain-like organs were first proposed in 2013. These “mini-brains” are used to simulate and study genetic diseases, major mental diseases, neurodegenerative diseases such as Alzheimer’s disease, and even human evolution.

The mini brain is the size of a pea, yet it can reproduce key brain functions. They are a recent research hotspot, and scientists believe they could eventually be used to simulate neurological diseases that are currently unsuitable for research in rodents or other animals.

Color scanning electron microscope image of neurons (orange) in contact with the nanowire array

Image source: Thiago Arzua, Massive Science

Past research has successfully identified genetic and protein changes associated with these diseases. However, investigating changes in the function of the affected brain, namely how the patient’s neurons work and how they interact with other cells, is still a challenge. Neurons communicate with each other by transmitting electrical signals, so in order to fully understand how they work, we need to study how electrical cells work.

At present, scientists have known that the mini-brain can produce spontaneous action potentials, but there is still a gap between simple action potentials and complex thinking activities.

The action potentials that occur at specific frequencies in the brain are called neural oscillations, or brain waves. Brain waves of different frequencies are related to different mental states. For example, brain waves during deep sleep oscillate at a frequency of 1 to 4 times per second. Brainwaves are also associated with different diseases. Therefore, if brain-like organs become the disease models that scientists need, they must be able to generate brainwaves or other electrical activities.

Illnesses such as Alzheimer’s and schizophrenia are complex, and in most cases, electrical activity in the brain undergoes more subtle changes before significant damage is caused to neurons.

Now, a recently published article found that mini-brains do produce brain waves. Led by Cleber Trujillo (Cleber Trujillo) , including Allison Muautelli (Alysson Muotri) recorded electrical activity generated by brain-like organs within 10 months. Other brain-like organ research generally focuses only on organoid development in the previous months, as the mini-brain develops a clear outline structure and stops growing in just two months. This new study shows that the longer the brain-like organs are cultivated, the more complex their cellular composition and the more complicated the electrical activity of neurons.

— vecteezy

Trujillo and his colleagues found that in the fourth month, organoids developed slow brain waves similar to those produced by our human brain during sleep. Even when they form a certain structure and stop growing up, the composition of cell types is still changing, and cell diversity continues to grow over time. These cellular changes are likely related to changes in brain wave patterns.

To test the extent to which these mature brain-like organs mimic the human brain, the researchers compared the radio waves generated by brain-like organs with the EEG of premature infants. (EGG) . They used brainwave data from premature babies to train machine learning algorithms before applying them to brain-like organs. They found certain brain functions, such as spontaneous activity transitions (brain activity bursts necessary to form more complex neural connections) in preterm infants The brain is very similar to that in brain-like organs, and the longer the brain-like tissues that are cultured the closer they are. In other words, after 10 months of growth, brain-like organs begin to exhibit electrical activity similar to that of the fetal brain.

This is the first time that we have brain-like organs that can mimic fetal brains not only in structure and cellular composition. This raises complex ethical issues and questions whether we can move forward in brain-like organ research. In the near future, we may be able to create consciousness in the laboratory, and some philosophers and scientists are concerned about it.

Ethical and moral discussions on these scientific advances should begin now. We live in an age where technology is developing faster than the ethical discussions surrounding them, and we must prevent irresponsible use of these technologies.

— vecteezy

Perturbational Complexity Index (Perturbational Complexity Index, PCI) is a tool that can prevent scientists from crossing ethics in organoid research And ethical red line tools. PCI has not been thoroughly validated in humans, but has been proposed as a way to test brain activity in comatose and unconscious patients. By using some relatively harmless methods, such as transcranial magnetic stimulation (a method of stimulating the brain with magnetic coils) , doctors and scientists can temporarily Interrupt normal brain activity and measure how quickly it recovers. This can give some clues about the level of patient or brain-like organ awareness.

Thankfully, the absurd story of the brain in the tank only exists in science fiction. The progress of organoid research is exciting, and compared to other research on the mechanism of the disease, it opens the door to the treatment of human neurological diseases that we still have trouble with, such as Alzheimer’s disease, Parkinson’s disease and schizophrenia.

The organoid domain is special and requires the input of different experts to ensure that we are ethical and responsible when we release the full potential of these micro-organs in order to help patients around the world.

This article is from the public number: Neural Reality (ID: Neurality) , author: Thiago Arzua