First-of-its-kind signal has just been detected in the human brain in astonishing discovery

Humans might have been around a long time, but the discovery of a new signal in our brain proves that we still don't know everything about ourselves.

And be 'we', I mean scientists. I rarely have a clue about what's going on inside my own brain.

Before we get into the new discovery, let's start with a bit of background. Like computers, our brains use an electrical voltage to carry out various operations - they're just using neurons to do so.

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A signal is formed by opening and closing channels that exchange charged particles such as sodium, chloride, and potassium in a process known as action potential, and the brain manages them chemically at the end of branches called dendrites.

Humboldt University neuroscientist Matthew Larkum explained: "The dendrites are central to understanding the brain because they are at the core of what determines the computational power of single neurons."

These ripples of voltage can trigger a message being passed on, and this system is potentially most complex in the cerebral cortex - the outer section of the human central nervous system.

Now, on to the discovery.

In 2020, researchers from institutes in Germany and Greece studied brain tissue removed during surgery on epileptic patients.

The scientists measured the electrical activity going on in sections of this tissue, and when analysing their structure they realised that individual cells in the cortex weren't only using the usual sodium ions to 'fire'.

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Instead, the cells were also relying on calcium, creating a combination of positively charged ions which resulted in voltage that scientists have never seen before.

Giving them the catchy name of 'calcium-mediated dendritic action potentials', or dCaAPs, for short, the scientists double checked their results in a handful of samples taken from patients with brain tumours and got the same findings.

When the cells were blocked with a sodium channel blocker, scientists still found a signal. It only stopped when they blocked calcium.

"There was a 'eureka' moment when we saw the dendritic action potentials for the first time," Larkum said.

Researchers found the individual neurons could act as 'exclusive' intersections in the brain, meaning they only permit a signal when another signal is graded in a particular fashion.

In the paper, publisher in the journal of Science, the team wrote: "These dCaAPs enabled the dendrites of individual human neocortical pyramidal neurons to classify linearly nonseparable inputs - a computation conventionally thought to require multilayered networks."

The unique form of cell messaging hasn't previously been seen, but recognising how it translates to higher functions is a question for another day.