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At Mind Matters News: Single neurons perform complex math — even in fruit flies

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The fly wants something simple — to avoid getting swatted or eaten, for example — but that requires some algebra:

We may not think of our neurons as performing complex calculations but they must do so in order to determine where sound is coming from or where a moving object is headed. For a long while, how they do so has been a mystery. Recently, researchers at the Max Planck Institute reported that they have “ discovered the biophysical basis by which a specific type of neuron in fruit flies can multiply two incoming signals,” the “algebra of neurons”:

We easily recognize objects and the direction in which they move. The brain calculates this information based on local changes in light intensity detected by our retina. The calculations occur at the level of individual neurons. But what does it mean when neurons calculate? In a network of communicating nerve cells, each cell must calculate its outgoing signal based on a multitude of incoming signals. Certain types of signals will increase and others will reduce the outgoing signal—processes that neuroscientists refer to as “excitation” and “inhibition.”

Max Planck Society, “The algebra of neurons: Study deciphers how a single nerve cell can multiply” at Phys.org (February 23, 2022) The paper is open access.

The fly is just trying to avoid getting swatted or eaten. But that is both more complex and more mathematical than we might have supposed:

News, “Single neurons perform complex math — even in fruit flies” at Mind Matters News (February 25, 2022)

Takehome: The fly’s specialized neurons either multiply or divide incoming signals in order to pinpoint the location of a sound or the direction of movement. How likely is this to happen without any intelligence behind nature at all?

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Human neurons are different from animal ones, researchers say.
A Canadian research team got a rare chance to compare live brain tissue from donors undergoing surgery with that of rodents. The human neurons’ interactions turned out to be of more different types, show more different features, and have more complex interactions than the rodent ones.


Researchers can’t explain: Memories drift from neuron to neuron. Memories are supposed to stay put in the neurons that lay them down. A recent study, published at Nature, shows that they move a lot… The mobile memories are only one of many recent remarkable neuroscience finds that have been challenging textbook wisdom.

Also: How do insects use their very small brains to think clearly? How do they engage in complex behavior with only 100,000 to a million neurons? Researchers are finding that insects have a number of strategies for making the most of comparatively few neurons to enable complex behavior. (Denyse O’Leary)

If we hadn't forgotten analog circuits and analog thinking, this would be less of a mystery. Neurons respond logarithmically. Adding the results of two logged inputs is the same as multiplying them. The bigger mystery is how each neuron is assigned its role. An analog computer has hundreds of op-amp modules, each settable to multiply or divide or add or subtract or perform a more complex curve fit. Someone has to turn the dials and run the wires. Each neuron is initially set to default, then migrates to its assigned location, sets its assigned functions and curves, and plugs in its approriate wires by RECOGNIZING the neurons it's meant to connect with. This process is more like a society than a computer. polistra

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