As humans, we tend to take the most powerful supercomputer in the world for granted: it has a roughly 38-petaflop processing capacity and 2.5 petabytes of memory (or 2.5 million gigabytes), yet only runs on a mere 12 watts of energy. And luckily, we all have one: the human brain. Only recently have silicon-based supercomputers caught up to the brain in raw computational power, with China’s 93-petaflop Sunway TaihuLight supercomputer coming online in June of last year. However, a new discovery made by the University of California, Los Angeles (UCLA) suggests that our brains might be up to one hundred times more powerful than previously suspected.
Neurons in the brain are made up of three major parts: the soma, the central part of the cell; the axion, a singular branch that extends out from the cell to send signals to other neurons; and a multitude of dendrites, multiple branches coming off of the main cell that receive signals from other neurons’ axion transmitters. Previously, it was assumed that a neuron’s soma was where the cell’s processing was done, due to the activity of electrical "spikes" generated there, with the role of dendrites simply being passive conduits that passed the information between the cells.
But the UCLA study has found that dendrites aren’t so passive, generating spike activity of their own — up to ten times more than what the central soma generates.
"Dendrites make up more than 90 percent of neural tissue," explains senior study author Mayank Mehta. "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."
Between making up roughly 90 percent of the brain’s neural mass, and the expected activity within the individual neurons being ten times what was previously assumed, this finding suggests that the processing power of the human brain may be 100 times greater than traditionally believed.
The study’s findings also indicate that the activity displayed by the dendrites wasn’t as simple as the digital manner that neurons were previously believed to operate under, but rather a hybrid analog/digital nature was uncovered:
"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," explains Mehta. "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."
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