Dendrites: The Beginning Of A Revolution

For many years, neuroscience has used different tools to try to “listen” to the conversations of neurons. In the same way that linguists decipher an unfamiliar language, scientists try to decode neural firing patterns to try to figure out the grammar of the brain. In these attempts, it seems that new stars have been born: the dendrites.

The latest research seems to be showing that neuroscience, when it comes to estimating our brain’s capacity, has only been scratching the surface. The University of UCLA discovered a hidden layer of neural communication through dendrites. This means that the brain’s capacity could be up to 100 times greater than previously thought.

This discovery can significantly change the foundations of conventional neuroscience. Until a few months ago, the foundations of neuroscience were supported by the belief that dendrites were something like a passive wiring that carried electrical signals to the neural body, the soma. But this research showed that dendrites are much more than just passive conductors. Dendrites generate their electrical signals, in peaks five times larger and more frequent than the peaks that come from the nuclei of neurons.

What does this discovery mean?

We are talking about a very radical change in the knowledge that neuroscience has about the functioning of the brain. Among other things, it is possible that learning processes occur at the level of dendrites and not in the bodies of neurons.

Conventional neuroscience has held that the electrical signals emitted by cell bodies are the foundation of our cognitive abilities. We now know that dendrites do not have a passive function and that they also emit their own electrical signals.

If this isn’t surprising in itself, the researchers found that dendrites are also smart. They are able to adapt their electrical firing over time. This type of plasticity has only been observed so far in neuronal bodies. This suggests that the dendrites could learn on their own.

Because dendrites are much more active than the cell body, we can begin to intuit that much of the information generated in a neuron is done at the level of the dendrites without them informing the cell body. That is, dendrites can act as a computing unit and process their information. An independence that a few months ago was not even suspected.

Brain capacity: research

The research team of Dr. Mayank R. Mehta devised a system that allows electrodes to be placed close to rat dendrites. This system makes it possible to capture electrical signals from the animal during the time it is awake and performing its daily activities, as well as during sleep. In this way, they were able to listen to the electrical activity of the dendrites for four days in a row and transmit it live to the computers.

The electrodes were implanted in the area of ​​the brain linked to movement planning, the posterior parietal cortex. What they managed to capture was that during periods of sleep the electrical signals looked like irregular waves, each signaling a peak.

That is, while the rats slept, the dendrites chatted with each other, and they did so in electric shots up to five times faster than those originating in cell bodies. During waking periods the rate of fire increased tenfold.

Dendrites: measurers of the here and now

Another shocking discovery during this research was found in the type of signal emitted by dendrites. The electrical signals from the dendrites could be digital, but they also showed large fluctuations, almost twice as large as the spines themselves. This type of wide-range fluctuation demonstrates that the dendrite also exhibited analog computing activity. Something that had not been seen before in any pattern of neural activity.

What this type of emission from the dendrite calculates appears to be related to time and space. By observing rats behaving in a maze, two types of signals were distinguished. One in the form of spikes from the cell body in anticipation of a behavior. In this case it was before turning a corner. While the dendrites emitted their calculation signals just as the animal turned the corner.

It seems that neuroscience has been underestimating the computational power of the brain. From the perspective of volume alone, and because dendrites are 100 times larger than soma, we could assume that the brain actually has a hundred times more processing power than previously thought. It seems that the neuron will no longer be the basic computational unit of the brain, the dendrites having taken over.