In 1935, Erwin Schrödinger, peering into the equations of quantum mechanics, saw something strange: two particles could be linked so tightly that the state of one instantly determines the state of the other, even if they are separated by kilometers. He called this "entanglement" and admitted that he considered it not a property of reality but rather a flaw in the theory. Nearly ninety years later, entanglement has become a working tool for physicists: it is measured in laboratories, used in quantum computers, and tested on satellites. Now a group of researchers has asked a bold question: could a similar connection be hiding in our own brains?

Neurons communicate via electrical impulses, and their collective activity resembles an orchestra where each instrument plays its own part, yet together they create a single symphony. This orchestra has no conductor: order emerges by itself from the chaos of random fluctuations. The authors of the new work show that if you take these fluctuations and compute their covariance matrix, a table describing how changes in one part of the network affect another, then after normalization it becomes a density matrix. And that is no longer just statistics but a full-fledged quantum state. Thus, from the classical physics of neurons, without any mysticism, a quantum formalism emerges.

The key concept the researchers introduce is "mental entanglement." This does not mean that neurons are literally entangled like photons in Aspect's experiment. Rather, it refers to a mathematical structure: inseparable correlations between observations of different brain regions. The authors distinguish two kinds of such entanglement. The first is entanglement of observables, when measurements performed on the system cannot be done simultaneously, just as in quantum mechanics you cannot precisely measure both position and momentum. The second is entanglement of states, which requires the brain to consist of several subsystems with special communication channels between them. This is where ephaptic coupling comes into play: neurons communicate not only through synapses but also through the electric fields they generate themselves. This "wireless network" could be the very channel that gives rise to entangled states.

Previously, quantum-like models of cognition, which explained paradoxes in decision-making, hung in the air: it was unclear how to derive quantum structures from neurophysiology. Now the bridge is built. The covariance matrix of random fluctuations, after normalization, becomes a density matrix, and this is not a metaphor but a rigorous mathematical fact. Practical benefits are not far off: quantum-like diagnostics based on EEG are already used for depression and epilepsy, but until now they lacked a solid theoretical foundation. Mental entanglement could provide that foundation. Moreover, it offers a formal language for describing one of the hardest problems in neuroscience, the binding problem: how the brain combines disparate features, color, shape, motion, into a single conscious percept.

If the hypothesis is confirmed, the brain would turn out to be not just a complex classical network but a system that uses quantum-like algorithms for information processing. This would open the way to new computational architectures inspired not by the structure of neurons but by the principles of their collective play. An orchestra without a conductor, it turns out, is capable of quantum tricks. And perhaps it is in this invisible score that the secret of consciousness is written.