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Genius-Level Neurons

Our understanding of how neurons function is currently being reframed.

Teachers lie. It happens more often than you’d think. We don’t want to do it. It’s just that telling the truth is hard.

We lie for a few reasons. First, we may not know the complete story. Often, as an individual or a scientific community, we just don’t fully know how something works. It’s hard to teach half-truths, and so we massage the story to make it complete. Second, the whole story may be too complicated and perhaps not critical for this level of learning. So we simplify the story, especially in introductory classes at university, so that a framework may be put in place, like the skeleton of a building, before moving on to the details in later courses. Or finally, at other times, advances mean our simple story is quickly becoming out of date, and we need time to reframe our understanding, but we keep telling the simple story even when we know it’s not exactly the truth.

Such is the case with neurons. Our understanding of how neurons function is currently being reframed. In my intro psychology course, I talk about neurons as three-part cells. First, there are dendrites, which receive signals, combine them and send the result to the cell body. If the combined input is strong enough, the cell body sends its own signal as an electrical spike through the third part of the neuron, the axon. At the end of the axon are areas, terminal buttons, that release neurotransmitters, which then act on the dendrites of the next neuron, and so the signal gets sent through the brain. 

Dendrite superstars

We have long known that neurotransmitter release at the end of axons is complex, with multiple receptors, including some on the sending neuron, that make for a feedback system with numerous loops. Recently, we have discovered that what we thought were simple collectors of input, the dendrites, also have sophisticated information processing capabilities. In the past, we assumed that all the dendrites do is add up the positive and negative inputs and present a total to the cell body. But in a recent paper in Science, Albert Gidon and colleagues found that neurons in the cortex have additional ways to process information received in an individual dendrite (a neuron has many dendrites). Dendrites have receptors that respond to an input with a strong response, but if the input continues the response gets much smaller. Effectively, if a dendrite receives input from only one of two inputs, it will signal, but if both inputs occur together, then the signal does not happen.

Computer scientists call this an “exclusive OR gate.” In addition to other known actions at the dendrites, it suggests a whole new level of information processing within a single neuron that exponentially increases the complexity of our brains. The neuron itself has become a brain within the brain. Currently, artificial intelligence systems have multiple layers of electronic units that mimic the simplified neurons discussed above. These have brought impressive strides in what computers can do and learn. Computers can teach themselves complex games like checkers, chess and go, even playing them better than humans. We are getting to the point where these artificial intelligence programs are supplementing our driving, providing emergency braking and other safety features. At some point, AI will be driving cars and trucks for us. But now we find that, in the human brain, neurons are considerably more complex than the units used in artificial intelligence systems, suggesting that it will be a long time before these systems match overall human abilities, and a long time before we fully understand how our brains work.

Indeed, we are “wonderfully made” (Ps. 139:14), and I’m trying my best not to mislead you, although as I tell my first class in the term, at least 10 percent is probably a lie.

Author

  • Rudy Eikelboom is a Professor of Psychology, at Wilfrid Laurier University, who has emerged from the dark side of the University after being department chair for 9 years and now teaches behavioural statistics to graduate and undergraduate psychology students. His retirement looms and he is looking forward to doing more writing on the implications of modern science for our Christian faith. Currently, he serves as a pastoral elder at the Waterloo Christian Reformed Church.

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