information storage

A stack of pages that has been flipped through many times remembers it: some sheets lie flat, others stick up, and creases remain here and there. Layered materials behave much the same way when ions enter them.

A jazz trio plays in the dim light of a club. The pianist leads the melody, the bassist holds the rhythm, and the drummer sprinkles out rolls. If you listen only to pairs of musicians, you can catch how the pianist adjusts to the bass or the bass to the drums.

Imagine a large orchestra without a conductor. Each musician hears everyone else and adjusts to the collective hum. If every instrument amplifies its neighbors, the sound builds to a screech; if some occasionally dampen it, the orchestra may fall into silence or break into cacophony.

In a nine-story building with a thousand rooms on each floor, some people whisper and others shout. Neighbors pass the message along, but if everyone speaks too softly, the message fades by the third floor. If too loudly, by the top floor it becomes an unintelligible roar. Between these extremes, there is a regime where a whisper makes it all the way through without distortion.

A beam of light enters a glass cell filled with cesium vapor and changes the internal state of the atoms: this is how information is recorded. A moment later, another beam reads it out by how the atoms absorb light. It's not a hard drive, but rather a notebook that turns its own pages. Eight such "pages" are created by an acousto-optic deflector — a device that bends light with sound.

A person flips a coin to make a decision. They stand still — the coin lands heads. They take a few steps, and flip again. It would seem walking shouldn't affect the coin. But what if the walk itself changes how often they decide to simply repeat the previous toss? That's exactly what researchers tested.

Holding in mind the exact position of a pen as it's slowly moved is a routine task for the brain. For artificial neural networks, it's nearly impossible. Standard recurrent networks like GRU and LSTM tend to break continuous motion into rigid steps: the pen doesn't glide smoothly but jumps from point to point.

In the long extensions of a neuron, the dendrites, tiny couriers are constantly bustling about. These are messenger RNA molecules carrying instructions for protein assembly. Their journey starts at the cell body and ends at synapses — contacts with other neurons.

A stadium packed with fans hears the announcer’s voice for the first time, and instantly the whole place erupts. The message sounds again and again. Only a handful of people in nearby rows respond. That’s roughly how neural networks behave in brain organoids — tiny lab-grown replicas of the brain.

A bacterium swims toward food. A chemical signal guides it forward, but with each movement the signal changes. A loop emerges: sensation, action, new sensation. The authors turned this loop into a measurable quantity.

The human mind is like a construction set that builds itself. New ideas don't die with their creators: they are passed on, mixed, and selected. This process is called cultural evolution: useful inventions stick, useless ones are forgotten. That's how a ratchet works — a mechanism that only turns forward. But what exactly happens in the head when one thought displaces another?

A city at night: lights on in some windows, dark in others. If you connect with lines the windows that light up simultaneously, you get a web of connections. Researchers studied such a web in tiny brain organoids — living clusters of nerve cells grown in the lab.

The meditating brain is an orchestra, and attention is the conductor. When you're focused on your breath, all instruments play in harmony. But suddenly, a thought-cello plays a false note: that's mind wandering. An experienced conductor doesn't panic: they instantly catch the dissonance and gently guide the orchestra back to the main melody — the breath.

The modern standard approach to AI training is like a child locked in a library: he remembers millions of books but doesn't know that fire burns and falling hurts.

Chatting with living neurons is like tuning an old radio: it's not enough to find the right frequency: you've got to aim the antenna too.

After a stone is thrown, the circles on water vanish, but the liquid retains microscopic oscillations. The slightest gust, and ripples appear again. Neural networks behave similarly. When electrical signals quiet down, the memory of them remains in the contact points — synapses.

In the grand orchestra of the universe, every instrument has its own rhythm. Electrons in an atom make quantum leaps in femtoseconds, neurons in the brain exchange signals in milliseconds, and a human needs tenths of a second to become aware of the 'now.' Physicists have long sought the conductor…

Why do some systems, from gene networks to air travel, preserve imprints of the past longer than others? For a long time, network science blamed topology: the number of connections, modularity, spectrum. But two networks with the same skeleton can remember and forget in completely different ways.

The brain doesn't learn every task from scratch: it transfers experience from one activity to another. But how do you know which tasks are truly related? Neuroscientists came up with a clever trick: let an artificial network "peek" at brain activity during one task and try to predict activity during another. If it works well, the tasks are close.

A neuron sends a signal to its neighbor. The neighbor doesn't respond immediately — the impulse travels along the process at a finite speed, like a letter delayed in transit. Usually, such a delay is considered a nuisance, but in this new work, it becomes the conductor. When two excitable neurons are connected with a delay, a rhythm spontaneously emerges between them.

The open archives OpenNeuro and NEMAR hold 791 recordings of the brain's electrical activity from nearly forty thousand people. In total, that's 86,051 hours of signals — roughly ten years of continuous listening. Previously, to take even one such recording off the shelf, you had to write thousands of lines of code: download, unzip, fix format errors, and slice it into chunks of the desired length.

In the 1990s, philosopher John Searle devised a thought experiment: a person sits in a room and, without knowing Chinese, follows instructions to produce correct answers in Chinese. From the outside, it seems they understand the language, but inside, it's just mechanical rule-following.

A neural network, like a sheet of graph paper, receives homogeneous signals at its input, and draws its own coordinate grid. Initially, connections between inputs and network cells form a gentle hill: the response is strongest at the center and fades toward the edges.

A supermarket cashier at rush hour doesn't memorize every scanned item: they keep the running total in their head and watch the queue. The brain allocates its resources similarly: the expensive, precise cortex (responsible for deliberation) and the simpler, economical subcortical nuclei (where habits live) work in tandem.

In a grand courtroom, a meeting is in session. Hundreds of translator-neurons simultaneously hear fragments of phrases, and must piece them into a single coherent picture. This is exactly how large brain networks turn scattered signals from the eyes into a unified object image.

A tightly stretched sheet lies on a table for days. Outwardly it's still, but the fabric fibers retain tension — loosen one edge slightly, and wrinkles will run across it, rearranging the whole pattern. That's roughly how a layer of epithelial cells behaves at rest. It doesn't just freeze; it accumulates mechanical stress — a kind of cellular memory of past movements.

The hand traces the word "mom" in the air — familiar arcs and strokes. The brain, meanwhile, is not flipping through a photo of each letter. It launches a chain of simple movements.

A person hunting for keys mentally runs through places where they might be. A bird that tucked hundreds of seeds into crevices in autumn retrieves them flawlessly in winter. How can a brain hold so many addresses when all birds have roughly the same number of neurons? The answer lies in geometry.

A melody plays, and the brain doesn't just listen note by note. It works like a conductor who already knows the score: each next note is expected because the previous ones still echo in memory. But how do neurons hold on to that echo?

Three twins on the run constantly change clothes. That's roughly how neutrinos behave — nearly elusive particles that pass through us by the trillions every second.

Imagine a river that doesn't flow in an open channel but through the inside of a sponge, with its currents shifting from place to place. That's a good way to think about the brain's glymphatic system: a network of ultra-fine channels around blood vessels, through which cerebrospinal fluid seeps into the tissue and washes away the waste that has piled up during the day.

A summer meadow surfaces in memory not just as a picture — along with it come the scent of grass and the warmth of the sun. The brain glues sensations into a single image, and that image holds up better than any one sensation alone. But exactly how neurons stitch the visual to the olfactory has long been a mystery.

An ordinary phone battery breathes — not with air, but with contact. Inside a solid body, where there are no liquids, lithium presses against the electrolyte (the ion-conducting substance) during charging and pulls away during discharging, like a lung on inhale and exhale. This 'breathing' is not poetry but physics: each cycle creates and destroys the contact points through which current flows.

The brain constantly juggles tasks: it reacts to a sharp sound, solves an equation, or drifts into daydreams. Scientists have long suspected that switches between different "scenarios" of neural network activity underlie this, but extracting them from the chaos of electrical signals was difficult.

The brain is like a multi-story building: lower floors process simple signals, while upper floors assemble them into complex perceptions. Scientists have long suspected that this order is tied to how neurons work together. But exactly how has remained a puzzle.

Holding a phone number in your head while you dial it: that's working memory. In the brain, a group of cells is responsible for this, sending signals to each other like people passing a bucket along a chain. But every transfer has a cost: it requires messenger substances that get used up.

A neural network learning something new is like a traveler in mountainous terrain. Each piece of learned knowledge is a depression in the landscape into which the traveler rolls and gets stuck. To escape and reach a new basin, energy is needed. But as the traveler gains experience, the walls of their pit become steeper, and each subsequent climb requires more effort.

Speech is like an orchestra where every note must sound at just the right moment. The brain turns a thought into a chain of sounds in a fraction of a second, and until now it was unclear how it manages this hierarchy — from individual sounds to syllables to whole words.

A handful of sand on a table is just a pile. But if you shake the grains just right, the pile starts behaving like a memory: it remembers which motion follows which. In the new experiment, particles were moved cyclically, and after training, they reproduced the desired pattern even without a full command. The secret lies in the contacts between particles.

Neurons in the brain and nodes in artificial neural networks don't just fire with simple yes/no signals; they also handle smoothly varying quantities, like where an object is and how big it is. But neural responses are finicky: the same stimulus triggers slightly different bursts of activity each time.