Tononi
Article
Tononi is a recurring person in the Astral Codex Ten archive, appearing 3 times across 3 issues between March 16, 2021 and November 20, 2025. The archive places it in contexts such as “In Tononi’s original paper , he says that the best evidence supports synaptic renormalization in non-REM sleep”; “Tononi’s original paper”; “IIT proponents (including Tononi, a true great of neuroscience)“. It most often appears alongside Anthropic, Giulio Tononi, Integrated Information Theory.
Metadata
- Category: People
- Mention count: 3
- Issue count: 3
- First seen: March 16, 2021
- Last seen: November 20, 2025
Appears In
Related Pages
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- Anthropic (2 shared issues)
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- Giulio Tononi (2 shared issues)
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- Integrated Information Theory (2 shared issues)
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- OpenAI (2 shared issues)
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- Scott Aaronson (2 shared issues)
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- 2020 election (1 shared issues)
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- @eigenrobot (1 shared issues)
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- @jeremychrysler (1 shared issues)
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- Adam Mastroianni (1 shared issues)
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- Adversarial examples (1 shared issues)
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- Aella (1 shared issues)
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- aella.ai (1 shared issues)
External Links
Source Context
Recovered passages from the original issue text. When the raw archive preserved outbound links inside the source passage, they are listed directly under the quote.
R&K start by reviewing the synaptic homeostasis hypothesis of sleep developed by neuroscientist Giulio Tononi (equally famous around these parts for his integrated information theory of consciousness, see eg Scott Aaronson's discussion here). As you learn stuff throughout the day, your brain builds new synaptic connections representing what you learned. For example, as you read this article connecting depression and sleep, your brain might be forming new synapses between neurons storing information about these two concepts (or strengthening existing synapses). That means as time goes on your brain will get more and more synapses, the synapses will become stronger and stronger, and everything will be more and more connected to everything else. But synapses take lots of energy to maintain. And "everything is maximally connected to everything else" works well for conspiracy theorists and Zen masters, but less well for neural networks trying to perform specific computations.
Inline links: synaptic homeostasis hypothesis of sleep, integrated information theory of consciousness, here
You can't renormalize while the network is running; you want to turn it off first. Tononi thinks this is the point of sleep. You turn off the network. You send a bunch of brain waves through to figure out average synapse level. Then you gradually downgrade and prune synapses until they're back at your set point. He cites lots of research showing that people gradually accumulate more and stronger synapses during the day, then lose them again during sleep, plus lots of reasons to think that the processes that happen during sleep are the sort of processes that would renormalize synapses.
What is the role of REM vs. non-REM sleep? Depressed people have much more REM sleep than non-depressed people. Serotonin seems to decrease REM sleep, so unsurprisingly SSRI antidepressants decrease REM sleep a lot (not just in depressed people, in everybody). This would lend itself very nicely to a theory where REM sleep is involved in decreasing synapse strength, depressed people have too much of it, they end up with overly weak synapses, and that's what depression is. In this model, antidepressants would treat depression by increasing serotonin levels in a way that represses REM. The problem with this is that in Tononi's original paper, he says that the best evidence supports synaptic renormalization in non-REM sleep; he doesn't have a great idea what REM is doing. He does mention one possibility is that non-REM sleep renormalizes most of the brain, but for some reason it doesn't work on the hippocampus, and REM sleep renormalizes the hippocampus. And some of the studies on depression and synaptic density point to the hippocampus in particular. But others don't, and this connection seems kind of forced. I think R&K mostly focus on slow-wave sleep and think it's renormalizing incorrectly rather than just too much or too little.
Inline links: decrease REM sleep a lot, original paper
34: Neuroscientist Erik Hoel discusses the new open letter condemning the integrated information theory of consciousness. I agree with Hoel: IIT is a weird theory, and I don’t personally believe it, but the few attempts to test it have been mildly supportive (including the most recent). Consciousness is inherently hard to study, but IIT proponents (including Tononi, a true great of neuroscience) are trying their best and have behaved entirely responsibly. The signatories’ attempts to (without any argument) go straight to the media and tar it as “pseudoscience” and “misinformation” don’t lower my opinion of IIT at all, but does lower my opinion of the letter signatories. (EDIT: the signatories defend their perspective)
In 2004, neuroscientist Giulio Tononi proposed that consciousness depended on a certain computational property, the integrated information level, dubbed Φ. Computer scientist Scott Aaronson complained that thermostats could have very high levels of Φ, and therefore integrated information theory should dub them conscious. Tononi responded that yup, thermostats are conscious. It probably isn’t a very interesting consciousness. They have no language or metacognition, so they can’t think thoughts like “I am a thermostat”. They just sit there, dimly aware of the temperature. You can’t prove that they don’t.