My understanding of brain vasculature suggests that you should cool the carotid arteries in the neck, not the scalp. The scalp is fed by the external branch of the carotid, while the brain is fed by the internal branch. So cooling the scalp won’t cool the blood going to the brain.
There has been research on using localized microwave heating to cook brain tumors. Forty five years ago, it was located in the basement of building 26 at MIT. My father looked into it and said that it was hard to get good localized heating because heat was carried away so fast by the blood.
Epistemic status: all from memory, don’t have time for research, got to go now. 30% chance I’ve gotten something importantly wrong.
You are right that the scalp is less than ideal. The forehead, neck, insides of the nose, and I think the upper parts of the cheek are all better for cooling the brain. I believe the best method found is one where cold dry air is pumped in one nostril and out the other to greatly increase evaporative cooling from the inside of the nose, which cools the blood moving into the brain
A water cooled forehead combined with a water cooled neck pad might work well
Sorry if I’m misunderstanding, but this post seems ignorant of Newton’s law of cooling. If the brain is 1° warmer than the blood, then it should cool about twice as fast (in °C/minute) as if it’s 0.5° warmer than the blood, right? So you shouldn’t have tables listing “cooling rate” measured in °C/minute, but rather something like “cooling half-life” (measured in minutes) or “cooling decay rate” (measured in minutes⁻¹) or things like that. You’re dividing a cooling rate (°C/minute) by a temperature difference (°C) to get the proportionality coefficient, and the °C cancels out.
I think a lot of claims in this post are dubious on account of that error.
Re: Newton's law of cooling - I'm not sure if it applies as much to the brain.
This is because the brain has other cooling mechanisms that kick in when overheating is detected. Yawning, panting, sweating/evaporative cooling from the forehead, and also blood flow to the brain can increase as well.
Yeah - you are right the cooling curve is definitely not linear - but I stand by my point that the data clearly shows that the brains heat generation ability greatly outstrips its cooling ability.
due to Eliezer mentioning in a recent interview:
- Only cognitively boosted humans have a chance at aligning AI
- Cooling the brain through methods like water cooling is one of our best chances to boost human intelligence
Eliezer Yudkowsky said that cooling the brain through methods like water cooling is one of our best chances to boost human intelligence? I am skeptical. Can you try to find that interview?
I explicitly remembered hearing it, it was one of his recent book tour videos, but I have looked back and have not yet been able to find the timestamp
Preventing heat throttling makes sense, but the brain does not tolerate hypothermia well: see for example https://pubmed.ncbi.nlm.nih.gov/39884656/. The brain is likely alreA
The research seems to show that mild hypothermia slows down neural activity in the brain but does not damage it. Mild hypothermia is sometimes medically induced after stroke or TBI or protect the brain.
For those people with Alzheimers or dementia and hypothermia, I think their brain has other problems, and hypothermia is downstream of those other problems.
I am sharing this information due to Eliezer mentioning in a recent interview:
Think of the brain as a powerful computer with a small heat sink. Especially in small animal brains. Kiyatkin explains this well:
We found that brain temperature was consistently higher than arterial blood temperature, and that brain temperature increased prior to, and to a greater extent than … arterial blood… local metabolic consequences of … neural activity appear to be the primary source of increases in brain temperature.
Rodents brains can heat up quickly - under relatively normal situations like social interaction, their brain temperature can increase as fast as 1 degree over 5 minutes. Such heating rates, if sustained over 15-20 minutes, could cause permanent brain damage or spontaneous death.
Kiyatkin details how brain damage rates rise as brain temperatures increase:
The numbers of albumin‑ and GFAP‑positive cells strongly correlate with brain temperature, gradually increasing from ~38.5 °C and plateauing at 41–42 °C… Brains maintained at hyperthermia also showed… structural abnormalities… suggesting acute brain edema.”
He then details what happens once the brain crosses its upper limit temperature threshold:
At 29 °C, MDMA pushed temperatures in the brain to its biological limits (>41 °C), resulting in fatalities in most (83%) tested animals.
Dr. Kiyatkin found that rodents drop dead spontaneously from overheated brains if they take MDMA + are housed in hot climates + are exposed to highly stimulating situations like other rodents to mate with. And this occurs within a few hours and with a 90% fatality rate. (Am I allowed to link to Sci Hub full text here?)
The research seems fairly clear that rodent brains can heat an order of magnitude faster than they can cool:
| Condition (awake rats) | Approx. rate (ΔT/60 s) | Source |
|---|---|---|
| Social interaction | ≈ 0.18–0.20 °C/min (≈ 0.003 °C/s) | Kiyatkin 2019, Fig. 2 (2‑s bins, 0–60 s); text: “increases within the first 10 s and significant within 20–30 s.” (PMC) |
| Tail‑pinch (3 min) | ≈ 0.15–0.17 °C/min | Kiyatkin 2019, Fig. 2 (onset‑latency panels as above). (PMC) |
| 20‑s tone (auditory) | ≈ 0.05–0.06 °C/min | Kiyatkin 2019, Fig. 2 and Fig. 3 (habituation). (PMC) |
| Situation | Typical peak warming (ΔT) | Time back to baseline | Implied cooling rate | Quote / Source |
|---|---|---|---|---|
| Eating completed | ~1.5 °C | ~35 min | ≈ 0.043 °C/min | “…returned to baseline after ∼35 min.” PMC |
| Food‑seeking without eating (frustration) | ~1.2 °C | ~50 min | ≈ 0.024 °C/min | “…return to baselines after ∼50 min.” PMC |
| Brief arousal; small peak then recovery | ~0.6 °C (peak at ~10 min) | 20–30 min after peak | ≈ 0.03–0.06 °C/min | “…peaked at ∼10 min… returned to the baselines at 20–30 min.” PMC |
Rodents brains might also exhibit heat throttling just like a computer. When rodent brain are already heated, Kiyatkin observed:
Although correlation was weaker, locomotor response was also dependent on basal temperature, being stronger at lower levels and weaker at higher levels.
The above may also be true for humans, especially in certain brain regions. But it is hard to conduct these studies because they require physically inserting a temperature probe into the brain. Humans probably do have much larger heat buffering than rodents do - so they have the same problem but can go a little longer before heat throttling kicks in.
Boosting the cooling ability of the brain could allow it to run fast longer before heat throttling kicks in. There are already products that use water cooling to cool the head. Water is run through channels in pads that sit on the scalp. For some reason, cooling the scalp greatly reduces chemotherapy hair loss. So most products are sold for that purpose.
One of the main ways to cool the brain is evaporative cooling from the forehead. Have you noticed how much cognitive work is done in cooler climates with relatively low humidity? Seattle and the Bay Area. Evaporative cooling works an order of magnitude better in cool and dry than in hot and humid climates.
I think that brain cooling solutions have a decent chance to allow us to become superhuman.
I'm a software developer by profession. I have researched this topic for years. I have more to say on this topic. I have many other weird but powerful ideas.
Contact me if you want to work with me. I am interesting in forming a startup based on this idea or other ideas of mine.