The human brain is the central organ of the human nervous system, and together with the spinal cord, it forms the central nervous system. In this field, scientists have discovered a unique form of cellular messaging that occurs in the human brain that has not been seen before, and interestingly, this suggests that our brains are more powerful units of computation than we realized.
Early last year, researchers from institutes in Germany and Greece reported a mechanism in the brain's outer cortical cells that produces a new graded signal on its own, one that can provide individual neurons with another way to carry out their logical functions. By measuring electrical activity in sections of tissue removed during surgery on epilepsy patients and analyzing their structure using fluorescence microscopy, neurologists found that individual cells in the cerebral cortex use not only the usual sodium ions but also calcium.
This combination of positively charged ions released previously unseen voltages referred to as calcium-mediated dendritic action potentials, or dCaAPs. Brains especially those of the human species- are often compared to computers. This analogy has its limitations, but on some levels, it performs tasks in similar ways. And they both use the power of electric potential to carry out different operations. In computers, this is a fairly simple flow of electrons through junctions called transistors.
In neurons, the signal is 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 conduct these messages chemically at the end of branches called dendrites.
Humboldt University neuroscientist Matthew Larcom told Walter Beckwith, at the American Association for the Advancement of Science in January 2020 said, branches are fundamental to understanding the brain because they are the core of what determines the computational power of single neurons.
Dendrites are the traffic signals of our nervous system. If the action potential is large enough, it can be transmitted to other nerves, which can either block or transmit the message. And these are the rationales for our brains voltage ripples that can be communicated collectively in two forms: either an AND message (if x and y are turned on, the message is passed) or a message (if x or y is turned on, the message is passed).
It could be said that nowhere is the dense, wrinkled outer part of the human central nervous system more complex, the cerebral cortex. The second and third deep layers are also particularly thick, packed with branches that perform high-level functions that we associate with sensation, thought, and control.
The researchers took a closer look at the tissues of these layers, as they attached the cells to a device called a somato-neural patch synapse to send energetic potentials up and down each neuron, recording their signals.
To make sure that any findings were not unique to people with epilepsy, they reviewed their findings in a small number of samples from brain tumors. While the team conducted similar experiments on mice, the types of signals they observed traveling through human cells were quite different.
Finding a calcium-mediated effort is interesting enough. But modeling the way this sensitive new type of signal works in the cortex revealed a surprise.