Quote:Somas generate brief electrical pulses called "spikes" in order to connect and communicate with each other. Scientists had generally believed that the somatic spikes activate the dendrites, which passively send currents to other neurons' somas, but this had never been directly tested before. This process is the basis for how memories are formed and stored.
Scientists have believed that this was dendrites' primary role.
But the UCLA team discovered that dendrites are not just passive conduits. Their research showed that dendrites are electrically active in animals that are moving around freely, generating nearly 10 times more spikes than somas. The finding challenges the long-held belief that spikes in the soma are the primary way in which perception, learning and memory formation occur.
https://www.sciencedaily.com/releases/2017/03/170309150634.htmQuote:"Dendrites make up more than 90 percent of neural tissue," said UCLA neurophysicist Mayank Mehta, the study's senior author. "Knowing they are much more active than the soma fundamentally changes the nature of our understanding of how the brain computes information. It may pave the way for understanding and treating neurological disorders, and for developing brain-like computers."
Quote:Scientists have generally believed that dendrites meekly sent currents they received from the cell's synapse (the junction between two neurons) to the soma, which in turn generated an electrical impulse. Those short electrical bursts, known as somatic spikes, were thought to be at the heart of neural computation and learning. But the new study demonstrated that dendrites generate their own spikes 10 times more often than the somas.
The researchers also found that dendrites generate large fluctuations in voltage in addition to the spikes; the spikes are binary, all-or-nothing events. The somas generated only all-or-nothing spikes, much like digital computers do. In addition to producing similar spikes, the dendrites also generated large, slowly varying voltages that were even bigger than the spikes, which suggests that the dendrites execute analog computation.
So, what do y'all think? It seems like this could potentially open up lots of exciting avenues for research. I wonder how this might impact future studies of psychedelics and their action in the brain.
Quote:"We found that dendrites are hybrids that do both analog and digital computations, which are therefore fundamentally different from purely digital computers, but somewhat similar to quantum computers that are analog," said Mehta, a UCLA professor of physics and astronomy, of neurology and of neurobiology. "A fundamental belief in neuroscience has been that neurons are digital devices. They either generate a spike or not. These results show that the dendrites do not behave purely like a digital device. Dendrites do generate digital, all-or-none spikes, but they also show large analog fluctuations that are not all or none. This is a major departure from what neuroscientists have believed for about 60 years."