Active neurons generate electrical fields
Thesis - No spark of mind: Does the brain not work with electricity at all?
Not a spark of mind: doesn't the brain work with electricity at all?
A biophysicist argues that the brain is not governed by electricity but by mechanics.
Even the term “flash of thought” suggests that our brain is electronic. And that's how we learn it in schools and universities. For the Egyptians 1500 BC it was still clear: The soul and the mind are in the heart. The wrinkled organ under the skull, on the other hand, was not believed to do that. Which is why the embalmers gave the dead all sorts of organs for the afterlife, but not the brain.
The first to think that this is where the origins of all ideas might be, were the ancient Greeks. The great Aristotle, of all people, did not want to know anything about it: he considered the brain to be an organ for cooling the blood.
But four hundred years later it was clear to the Greek doctor Galen: The home of feeling and thinking is the brain. More precisely, the cerebrospinal fluid called "Spiritus animalis", in which sensations and thoughts wander around like nutshells on a river. It's an idea that today's brain researchers smile rather mildly. The focus is on around 86 billion neurons that repeatedly «fire», that is, generate electrical voltage, during their work. Which, as is well known, can also be observed in the twitching curves in the EEG (electroencephalogram).
One against all
But biophysicist Thomas Heimburg, now a professor at the Niels Bohr Institute at the University of Copenhagen, does not prevent this incontrovertible evidence from developing a completely different model of brain work. Electricity only plays a minor role here, and there is also a certain closeness to old Galen and his spirit.
Like a clove tree
The human brain contains around 86 billion nerve cells or neurons, the structure of which is reminiscent of a clove tree because they form extremely fine branches. Their cell processes can become very long and stretch from one side of the brain to the other. In doing so, they taper to a diameter of 0.1 micrometers.
The contact between the brain neurons is usually via synapses: there are 100 trillion of them. That's a number with 15 zeros - and it indicates that connecting is incredibly important in the brain. (ZI)
Heimburg found the impetus for developing his model from classics of physics such as Hermann von Helmholtz. A well-known core principle of thermodynamics goes back to him, according to which energy can change its shape, but can neither arise from nothing nor go back into nothing. And at that time - in the middle of the 19th century - Helmholtz also had the nerve conduction velocity in mind. “I consider it essential to read these historical works,” emphasizes Heimburg. Because they provided the basis for understanding physics.
At Heimburg, they led him to question the concept of anesthesia in medicine. According to this model, narcotics work by blocking the channels in the neurons where sodium and potassium ions otherwise flow in and out, creating an electrical charge. That sounds convincing at first glance, but there are actually a lot of narcotics such as laughing gas, ether and xenon, all with completely different compositions - and yet each of them should be able to block the ion channels of the nerve cells? Heimberg does not find this idea very convincing. There must be something much more fundamental at work: namely thermodynamics.
Heimburg is certain that neurons do not transmit electrical signals, but mechanical signals. And they use their cell membranes as a transmission path. It contains fat molecules that are normally liquid, but take on a liquid-crystalline consistency from a certain pressure or compression state. So you have to imagine an active neuron as a tube, in the shell of which a pressure wave spreads, in which the fat molecules change from the liquid-chaotic to the crystalline-ordered state and back again, which allows the neuron tube to come to rest again. The electricity visible in the EEG is created during this process, and it can also play the role of the pulse generator that sets the pressure wave in motion in the nerve wall - but it is no longer the basis of the signal transmission itself.
Accordingly, narcotics do not work by blocking ions, but by depositing themselves in the neuron membranes and preventing the conversion of the fat molecules from the liquid to the crystalline state.
Heimburg was able to substantiate this in a laboratory experiment. Just as he succeeded in demonstrating how the inhibiting effect can be levered out, namely by means of an increased initial impulse in the form of an extra strong electrical stimulus. To do this, the German biophysicist first gave his test subjects a local anesthetic with lidocaine and then gave them powerful electric shocks. Up to 40 milliamps, which normally flows through a five-watt light bulb! But then the nerve in the hand was active, as if it hadn't been anesthetized at all. And that speaks for the thesis of the pressure wave, which is finally set in motion by the heavy electric shocks; and not for the thesis of the ion channels, which are not suddenly freed from all their narcotic blockages just because the neuron has been electrocuted.
Colleagues are critically interested
Heimburg's theses are still not well received in neurology and brain research. The main criticism to be heard is that the ion channels do exist, and scientists have found hundreds of transport proteins in them, the modification of which in some cases had a major impact on the transmission of signals from neurons. Mike Brügger from the University of Zurich also emphasizes, however, that there are still many questions unanswered with regard to nervous stimulus transmission and that Heimburg's model is therefore “not unexciting”. The Swiss brain and pain researcher raises concerns that the electric shock experiment is interesting, but needs to be checked very carefully. First, we know that lidocaine can be broken down quickly in some cases. "Secondly, such high currents are not physiological and it is quite conceivable that the body has to conduct this current to compensate for it via other nerves, which could also explain the activation described," says Brügger.
Niels Birbaumer from the Wyss Center in Geneva considers the pressure wave model of nervous signal transmission to be “entirely plausible”, but it is difficult to prove with today's methods. For the brain researcher working on locked-in patients, one thing is certain: "I'll stick with the electricity for now." And the countless operated patients in this world shouldn't care whether the anesthetic used in them clogs the ion channels or prevents the pressure waves in the membranes - in the end, the only thing that counts is that you don't notice anything about the procedure.
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