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DavidFreely edited this page Nov 11, 2025 · 3 revisions

Sometimes at the beginning of a movie, you see something like: “Inspired by true events” or “Based on a true story.” Saying that “Artificial intelligence is like your brain” is a lot like that. It starts with a few facts, then the rest of the movie goes off in a different direction.

  • Source: Brain Simulator II _ The Guide - Charles Simon
  • Chapter: Chapter 3: AI is NOT Like Your Brain

Your brain is so different from AI’s Artificial Neural Networks (ANNs) that in this chapter I’ll focus on just three areas:

  • ANN neurons aren’t like biological neurons.
  • Artificial synapses are only a little like biological synapses
  • Backpropagation, the mainstay of AI learning, has no biological analog whatsoever.
  • Source: Brain Simulator II _ The Guide - Charles Simon
  • Chapter: Chapter 3: AI is NOT Like Your Brain

ANN neurons aren’t like biological neurons.

Here’s the initial problem. The biological neuron is a spiking device that cannot and does not output an analog value like the x’s and the output value in the illustration. Instead, neuron values are binary—either there is a spike or there is not. In a few cases, AI experts counter by saying: “No problem, just set the activation to a step function so the output will be 1 or 0.” But this ignores the accumulated charge from one cycle to the next, so we’d also need to add internal memory—not reflected in the neural network model.

  • Source: Brain Simulator II _ The Guide - Charles Simon
  • Chapter: Chapter 3: AI is NOT Like Your Brain, Neurons

Artificial synapses are only a little like biological synapses

Which brings us to synapses for a similar conversation. Once again, the neural network represents the weight of a synapse as a floating-point number, although the neuroscientists tell us that they have a limited number of discrete values. In the previous chapter, I explained how the more values a synapse might take on, the slower the learning process must be.

But let’s look at an even more fundamental problem. THERE IS NO WAY TO ACCESS THE WEIGHT OF A SYNAPSE PRECISELY.

  • Source: Brain Simulator II _ The Guide - Charles Simon
  • Chapter: Chapter 3: AI is NOT Like Your Brain, Synapses

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