Scientists have discovered a unique form of messaging between cells in the human brain that has never been seen before. The exciting discovery hints that our brains may be an even more powerful computing machine than we thought.
Early last year, researchers from institutes in Germany and Greece reported a mechanism in cells in the outer cortex of the brain that independently produces a new “graded” signal that could provide individual neurons with a different way to perform their logical functions.
By measuring electrical activity in tissue sections removed during surgery in epilepsy patients and analyzing their structure using fluorescence microscopy, neuroscientists discovered that individual cortical cells use not only the usual sodium ions but also calcium ions to “fire”.
This combination of positively charged ions produces previously unseen voltage waves called calcium-mediated dendritic action potentials, or dCaAPs.
The brain-especially the human brain-is often compared to a computer. This analogy has its limits, but on some levels they perform tasks in a similar way.
Both use the force of electrical voltage to perform various operations. In computers, it is a fairly simple flow of electrons through junctions called transistors.
In neurons, the signal is in the form of a wave of opening and closing channels that exchange charged particles such as sodium, chloride and potassium. This pulse of flowing ions is called the action potential.
Instead of transistors, neurons control these messages chemically at the ends of outgrowths called dendrites.
“Dendrites are central to understanding the brain because they underlie what determines the computational power of individual neurons,” said Humboldt University neuroscientist Matthew Larkum at the American Association for the Advancement of Science conference.
Dendrites are the traffic lights of our nervous system. If the action potential is significant enough, it can be transmitted to other nerves, which can block or relay the message.
